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MedWorm: BumetanideExcitatory Action of GABA in the Terminal Nerve Gonadotropin-Releasing Hormone Neurons The terminal nerve (TN)-gonadotropin-releasing hormone (GnRH) neurons have been suggested to function as a neuromodulatory system that regulates the motivational and arousal state of the animal and have served as a model system for the study of GnRH neuron physiology. To investigate the synaptic control of the TN-GnRH neurons, we analyzed electrophysiologically the effect of GABA on the TN-GnRH neurons. GABA generally hyperpolarizes most of the neurons in the adult brain by activating GABAA receptors while the activation of GABAA receptors depolarizes some specific neurons in the mature brain. Here we examined the GABAA receptor-mediated responses in the TN-GnRH neurons of adult teleost fish, the dwarf gourami, by means of gramicidin-perforated patch-clamp and cell-attached patch-clamp rec... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. In this study, we describe a novel chemically-induced, recessive mutant mouse line termed Slc12a1(I299F) exhibiting late-onset manifestation of Type I Bartter Syndrome. Homozygous mutant mice are viable and exhibit severe polyuria, metabolic alkalosis, marked increase in plasma urea but close to normal creatininemia, hypermagnesemia, hyperprostaglandinuria, hypotension, and osteopenia. Fractional excretion of urea is markedly decreased. In addition, calcium and magnesium excretions are more than doubled compared to wild-type mice, while uric acid excretion is two-fold lower. In contrast to hyperreninemia present in the human disease, plasma renin concentration in homozygotes is not increased. The polyuria observed in homozygotes may be due to the combination of two additive factors, a decr... Bumetanide Alleviates Epileptogenic and Neurotoxic Effects of Sevoflurane in Neonatal Rat Brain Conclusion: These results support the possibility that excitatory output of sevoflurane-potentiated [gamma]-aminobutyric acid type A/glycine systems may contribute to epileptogenic and neurotoxic effects in early postnatal rats. (C) 2010 American Society of Anesthesiologists, Inc. (Source: Anesthesiology) ORL 2009;71(suppl 1):1015 (DOI:10.1159/000265114) (Source: Karger Publishers) Bumex (Bumetanide) - updated on RxList Bumex (Bumetanide) drug description - FDA approved labeling for prescription drugs and medications at RxList (Source: RxList - New and Updated Drug Monographs) Authors: Gawenis LR, Bradford EM, Alper SL, Prasad V, Shull GE Anion secretion by colonic epithelium is dependent on apical CFTR-mediated anion conductance and basolateral ion transport. In many tissues, the NKCC1 Na(+)-K(+)-2Cl(-) cotransporter mediates basolateral Cl(-) uptake. However, additional evidence suggests that the AE2 Cl(-)/HCO(3)(-) exchanger, when coupled with the NHE1 Na(+)/H(+) exchanger or a Na(+)-HCO(3)(-) cotransporter (NBC), contributes to HCO(3)(-) and/or Cl(-) uptake. To analyze the secretory functions of AE2 in proximal colon, short-circuit current (I(sc)) responses to cAMP and inhibitors of basolateral anion transporters were measured in muscle-stripped wild-type (WT) and AE2-null (AE2(-/-)) proximal colon. In physiologic Ringers, the magnitude of cAMP-stimulate... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Prostaglandin E2-induced colonic secretion in patients with and without colorectal neoplasia Conclusions: Epithelial electrogenic transport is more sensitive to indomethacin in normal colonic mucosa from patients with previous or present colorectal neoplasia compared to colonic mucosa from control patients. Stimulated epithelial electrogenic transport through individual prostanoid subtype receptors EP1, EP2, EP3, and EP4 is not significantly different between neoplasia diseased patients and controls. This indicates that increased indomethacin-sensitive mechanisms in colonic mucosa from neoplasia diseased patients are not related to differences in functional expression of EP receptor subtypes. (Source: BMC Gastroenterology) The previously undescribed heterozygous missense mutation E758K was discovered in the human AE1/SLC4A1/band 3 gene in two unrelated patients with well-compensated hereditary spherostomatocytic anemia (HSt). Oocyte surface expression of AE1 E758K, in contrast to that of wild-type AE1, required coexpressed glycophorin A (GPA). The mutant polypeptide exhibited, in parallel, strong GPA dependence of DIDS-sensitive 36Cl– influx, trans-anion-dependent 36Cl– efflux, and Cl–/HCO3– exchange activities at near wild-type levels. AE1 E758K expression was also associated with GPA-dependent increases of DIDS-sensitive pH-independent SO42– uptake and oxalate uptake with altered pH dependence. In marked contrast, the bumetanide- and ouabain-insensitive 86Rb+ influx associated... Decreased NKCC1 Activity in Erythrocytes From African Americans With Hypertension and Dyslipidemia. ConclusionsNKCC1 activity is lower in erythrocytes of African Americans with essential hypertension and dyslipidemia than in Caucasian counterparts. We suggest that decreased NKCC1 may contribute to the feature of the pathogenesis of salt-sensitive hypertension seen in African Americans.American Journal of Hypertension 2009; doi:10.1038/ajh.2009.249. PMID: 20044742 [PubMed - as supplied by publisher] (Source: American Journal of Hypertension) Authors: Simard JM, Kahle KT, Gerzanich V Microvascular failure largely underlies the damaging secondary events that accompany traumatic brain injury (TBI). Changes in capillary permeability result in the extravasation of extracellular fluid, inflammatory cells, and blood, thereby producing cerebral edema, inflammation, and progressive secondary hemorrhage (PSH). Recent work in rat models of TBI and stroke have implicated 2 ion transport proteins expressed in brain endothelial cells as critical mediators of edema formation: the constitutively expressed Na(+)-K(+)-2Cl(-) cotransporter, NKCC1, and the trauma/ischemia-induced SUR1-regulated NC(Ca-ATP) (SUR1/TRPM4) channel. Whereas NKCC1 function requires adenosine 5'-triphosphate (ATP), activation of SUR1/TRPM4 occurs only after ATP deple... Conclusions: These data demonstrate that cerebral metabolism is significantly compromised during DKA, and further deterioration occurs during early DKA treatment, consistent with possible effects of cerebral hypoperfusion and "reperfusion injury". Treatment with bumetanide may help to diminish the adverse effects of initial treatment with insulin/saline. PMID: 20028943 [PubMed - as supplied by publisher] (Source: Diabetes) MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. An increase in blood pressure (BP) due to angiotensin II (ANG II) infusion or other means is associated with adaptive pressure natriuresis due to reduced sodium reabsorption primarily in proximal tubule (PT) and thick ascending limb (TAL). We tested the hypothesis that male and female mice would show differential response to ANG II infusion with regard to the regulation of the protein abundance of sodium transporters in the PT and TAL and that these responses would be modulated by aging. Young (~3 mo) and old (~21 mo) male and female mice were infused with ANG II at 800 ng·kg body wt–1·min–1 by osmotic minipump for 7 days or received a sham operation. ANG II increased mean arterial pressure (MAP), measured by radiotelemetry, significantly more in male mice of both... Developmental and functional studies of the SLC12 gene family members from Drosophila melanogaster The electroneutral cation-chloride cotransporter gene family, SLC12, contains nine members in vertebrates. These include seven sodium and/or potassium-coupled chloride transporters and two membrane proteins of unknown function. Although SLC12 family members have been identified in a number of lower species, the functional properties of these proteins are unknown. There are five SLC12 homologues in Drosophila melanogaster, including at least one member on each of the four main branches of the vertebrate phylogenetic tree. We have employed in situ hybridization to study the expression patterns of the Drosophila SLC12 proteins during embryonic development. Our studies indicate that all five members of this family are expressed during early embryogenesis (stages 1–6), but that spatial an... The renal bumetanide-sensitive Na-K-2Cl cotransporter (NKCC2) is the major salt transport pathway in the apical membrane of the mammalian thick ascending limb. It is differentially spliced and the three major variants (A, B, and F) differ in their localization and transport characteristics. Most knowledge about its regulation comes from experiments in Xenopus oocytes as NKCC2 proved difficult to functionally express in a mammalian system. Here we report the cloning and functional expression of untagged and unmodified versions of the major splice variants from ferret kidney (fNKCC2A, -B, and -F) in human embryonic kidney (HEK) 293 cells. Many NKCC2 antibodies used in this study detected high molecular weight forms of the transfected proteins, probably NKCC2 dimers, but not the monomers. Int... Secondhand smoke inhibits both Cl- and K+ conductances in normal human bronchial epithelial cells Secondhand smoke (SHS) exposure is an independent risk factor for asthma, rhinosinusitis, and more severe respiratory tract infections in children and adults. Impaired mucociliary clearance with subsequent mucus retention contributes to the pathophysiology of each of these diseases, suggesting that altered epithelial salt and water transport may play an etiological role. To test the hypothesis that SHS would alter epithelial ion transport, we designed a system for in vitro exposure of mature, well-differentiated human bronchial epithelial cells to SHS. We show that SHS exposure inhibits cAMP-stimulated, bumetanide-sensitive anion secretion by 25 to 40% in a time-dependent fashion in these cells. Increasing the amount of carbon monoxide to 100 ppm from 5 ppm did not increase the amount of i... Authors: Stewart AK, Vandorpe DH, Heneghan JF, Chebib F, Stolpe K, Akhavein A, Edelman EJ, Maksimova Y, Gallagher PG, Alper SL The previously undescribed, heterozygous missense mutation E758K was discovered in the human AE1/SLC4A1/Band 3 gene in two unrelated patients with well-compensated spherostomatocytic anemia (HSt). AE1 E758K oocyte surface expression, unlike that of wildtype AE1, required coexpressed glycophorin A (GPA). The mutant polypeptide exhibited, in parallel, strong GPA-dependence of DIDS-sensitive (36)Cl(-) influx, trans-anion-dependent (36)Cl(-) efflux, and Cl(-)/HCO(3)(-) exchange activities at near wildtype levels. AE1 E758K expression was also associated with GPA-dependent increases of DIDS-sensitive pH-independent sulfate uptake and oxalate uptake of altered pH-dep... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Authors: Tiwari S, Li L, Riazi S, Halagappa VK, Ecelbarger CM An increase in blood pressure (BP) due to angiotensin II (Ang II) infusion or other means is associated with adaptive pressure natriuresis due to reduced sodium reabsorption primarily in proximal tubule (PT) and thick ascending limb (TAL). We tested the hypothesis that male and female mice would show differential response to Ang II infusion with regard to the regulation of the protein abundance of sodium transporters in the PT and TAL, and whether these responses would be modulated by aging. Young (~3 months) and old (~21 months) male and female mice were infused with Ang II @ 800 ng/kg*bw/min by osmotic minimpump for 7 days or received a sham operation. Ang II increased MAP, measured by radiotelemetry, significantly more in... Hymenolepis diminuta: Effect of infection on ion transport in colon and blood picture of rats. Authors: Kosik-Bogacka DI, Baranowska-Bosiacka I, Salamatin R The aim of this study was to examine the effect of an infection with Hymenolepis diminuta on ion transport in an isolated colon and blood picture of rats. Fifty rats were orally infected with 5 cysticercoids of H. diminuta. The experimental groups of rats were assigned to four groups: group I - 8 days post-infection (dpi), group II - 16 dpi, group III - 40 dpi and group IV- 60 dpi. The control group comprised non-infected rats. The experiments consisted of measuring the transepithelial electrical potential difference (PD) and the transepithelial electrical resistance (R) of the rat colon under controlled conditions as well as during mechanical stimulation (MS) using a modified Ussing chamber. Ion transport was modified using... Activity-mediated plasticity of GABA equilibrium potential in rat hippocampal CA1 neurons. Authors: Yang B, Tadavarty R, Xu JY, Sastry BR The equilibrium potential (E(GABA-PSC)) for gamma-aminobutyric acid (GABA) A receptor mediated inhibitory postsynaptic currents (PSCs) in hippocampal CA1 pyramidal neurons shifts when theta-burst stimulation (4 pulses at 100 Hz in each burst in a train consisting of 5 bursts with an inter-burst interval of 200 ms, the train repeated thrice at 30 s intervals) is applied to the input. E(GABA-PSC) is regulated by K(+)/Cl(-)co-transporter (KCC2). GABA(B) receptors are implicated in modulating KCC2 levels. In the current study, the involvement of KCC2 as well as GABA(B) receptors in theta-burst-mediated shifts in E(GABA-PSC,) were examined. Whole-cell patch recordings were made from hippocampal CA1 pyramidal neurons (from 9-12 day old rats), in... Why funding epilepsy research matters Last night, Frances Jensen, MD, senior associate in Neurology, was featured in a piece on 60 Minutes about the prevalence of epilepsy and the importance of funding research into its cure. Watch the piece here, then keep reading below as Jensen describes how epilepsy is often overlooked as a public health problem and how researchers like her are trying to stop it in its tracks. Also watch below as Jensen shows Katie Couric what an epilepsy looks like from a molecular perspective. Watch CBS News Videos Online By Frances Jensen, MD Last night, research by myself and my team was featured on 60 Minutes in a wonderful story about the impact that epilepsy has on the people with it and the challenges of getting the public – including the agencies that fund research – to pay the disease the at... Frances Jensen on 60 Minutes: Why funding epilepsy research is important Last night, Frances Jensen, MD, senior associate in Neurology, was featured in a piece on 60 Minutes about the prevalence of epilepsy and the importance of funding research into its cure. Watch the piece here, then keep reading below as Jensen describes how epilepsy is often overlooked as a public health problem and how researchers like her are trying to stop it in its tracks. Also watch below as Jensen shows Katie Couric what an epilepsy looks like from a molecular perspective. Watch CBS News Videos Online By Frances Jensen, MD Last night, research by myself and my team was featured on 60 Minutes in a wonderful story about the impact that epilepsy has on the people with it and the challenges of getting the public – including the agencies that fund research – to pay the disease the at... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Unilateral Ureteral Obstruction Alters Expression of Acid-Base Transporters in Rat Kidney Conclusions: The expression of renal acid-base transporters is markedly decreased in the obstructed kidney, which may be responsible for the contribution of impaired renal H+ excretion and HCO3− reabsorption to the urinary acidification defect in response to unilateral ureteral obstruction. (Source: The Journal of Urology) A Comprehensive Review of the Loop Diuretics: Should Furosemide Be First Line? (November)(CE). CONCLUSIONS: Growing evidence demonstrates more favorable pharmacokinetic profiles of torsemide and bumetanide compared with furosemide. Furthermore, torsemide may be more efficacious and safer than furosemide in patients with HF. A trial comparing all 3 drugs would be required to confirm torsemide as the primary loop diuretic in patients with HF, but based upon limited current evidence, we recommend torsemide over furosemide. Currently, little evidence exists to support either torsemide or bumetanide as first-line treatment over furosemide in patients with other edematous disease states. PMID: 19843838 [PubMed - as supplied by publisher] (Source: The Annals of Pharmacotherapy) Developmental and functional studies of the SLC12 gene family members from Drosophila melanogaster. Authors: Sun Q, Tian E, Turner RJ, Ten Hagen K The electroneutral cation-chloride cotransporter gene family, SLC12, contains nine members in vertebrates. These include seven sodium and/or potassium-coupled chloride transporters and two membrane proteins of unknown function. Although SLC12 family members have been identified in a number of lower species, the functional properties of these proteins are unknown. There are five SLC12 homologues in Drosophila melanogaster including at least one member on each of the four main branches of the vertebrate phylogenetic tree. We have employed in situ hybridization to study the expression patterns of the Drosophila SLC12 proteins during embryonic development. Our studies indicate that all five members of this family are expressed during early emb... GABAergic signaling induces divergent neuronal Ca2+ responses in the suprachiasmatic nucleus network Intercellular communication between [gamma]-aminobutyric acid (GABA)ergic suprachiasmatic nucleus (SCN) neurons facilitates light-induced phase changes and synchronization of individual neural oscillators within the SCN network. We used ratiometric Ca2+ imaging techniques to record changes in the intracellular calcium concentration ([Ca2+]i) to study the role of GABA in interneuronal communication and the response of the SCN neuronal network to optic nerve stimulations that mimic entraining light signals. Stimulation of the retinohypothalamic tract (RHT) evoked divergent Ca2+ responses in neurons that varied regionally within the SCN with a pattern that correlated with those evoked by pharmacological GABA applications. GABAA and GABAB receptor agonists and antagonists were used to evaluate... This study examined the effect of thrombin on glutamate efflux from rat cortical cultured astrocytes using 3H-d-aspartate as radiotracer. The glutamate efflux was initiated by addition of 100 mM K+ plus 1 mM ouabain (K/O) to replicate extracellular and intracellular ionic changes that occur during cerebral ischemia. Upon exposure to K/O, astrocytes swelled slowly and progressively with no evidence of volume regulation. The K/O-induced swelling was inhibited by 65% with bumetanide and 25% with BaCl2, suggesting contribution of Na+/K+/Cl[minus] co-transporter and Kir channels. K/O-elicited 3H-d-aspartate that consisted of two phases. The first transient component of the release corresponded to 13.5% of total 3H-d-aspartate loaded. It was markedly reduced (61%) by the glutamate transporter bl... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. This study provides direct and convincing evidence for Cl– transport by MRCs of SW- and FW-acclimated euryhaline tilapia and the involvement of an apical NCC in Cl– uptake of MRCs of FW-acclimated fish. (Source: AJP: Cell Physiology) Previously, we demonstrated that genistein stimulated Cl– secretion in the mouse jejunum (Baker MJ and Hamilton KL, Am J Physiol Cell Physiol 287: C1636–C1645, 2004); however, the mode of action of genistein still remains unclear. Here, we examined the activation of Cl– secretion by the modulation of phosphodiesterases (PDEs) by genistein (75 µM) in the mouse jejunum with the Ussing short-circuit current (Isc) technique. Drugs tested included theophylline (10 mM), a nonspecific PDE inhibitor; 8-methoxymethyl-3-isobutyl-1-methylxanthine (8-MM-IBMX; 100 µM), erythro-9-(2-hydroxyl-3-nonyl)-adenine (EHNA; 40 µM), milrinone (100 µM), and rolipram (40 and 100 µM), which are specific inhibitors of PDE1–PDE4, respectively. Theophylline stimulat... Excitatory GABAergic Activation of Cortical Dividing Glial Cells Adult neocortex contains dividing satellite glia population even though their characteristics and functions have still remained unknown. Nestin+/NG2+ cells as major fraction of dividing glial cells express bicuculline-sensitive -aminobutyric acid A (GABAA) receptors and receive GABAergic inputs. Due to their high [Cl–]i, GABAergic activation depolarized the cells and then induced Ca2+ influx into them. To assess an effect of this GABAergic excitation, we looked for the expression of neurotrophic factors. Among them, we detected the expression of brain-derived neurotrophic factor (BDNF) on the cells. The level of BDNF expression was elevated after cortical ischemia, and this elevation was blocked by bumetanide, an inhibitor for NKCC1 that blocks the GABAergic depolarization. Furthermo... This study provides direct and convincing evidence for Cl(-) transport by MRCs of SW- and FW-acclimated euryhaline tilapia, and the involvement of an apical NCC in Cl(-) uptake of MRCs of FW-acclimated fish. Key words: Na+-Cl- cotransporter, osmoregulation, gills, ionoregulation. PMID: 19657057 [PubMed - as supplied by publisher] (Source: American Journal of Physiology. Cell Physiology) Blood-brain barrier (BBB) Na transporters are essential for brain water and electrolyte homeostasis. However, they also contribute to edema formation during the early hours of ischemic stroke by increased transport of Na from blood into brain across an intact BBB. We previously showed that a luminal BBB Na-K-Cl cotransporter is stimulated by hypoxia, aglycemia, and AVP and that inhibition of the cotransporter by intravenous bumetanide significantly reduces edema and infarct in the rat middle cerebral artery occlusion (MCAO) model of stroke. More recently, we found evidence that intravenous cariporide (HOE-642), a highly potent Na/H exchange inhibitor, also reduces brain edema after MCAO. The present study was conducted to investigate which Na/H exchange protein isoforms are present in BBB ... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. [Small intestine] Structural and functional changes of the duodenum in human norovirus infection Conclusions: Norovirus infection leads to epithelial barrier dysfunction paralleled by a reduction of sealing tight junctional proteins and an increase in epithelial apoptosis, which may partly be mediated by increased cytotoxic intraepithelial lymphocytes. Furthermore, active anion secretion is markedly stimulated. Thus, the diarrhoea in norovirus infection is driven by both a leak flux and a secretory component. (Source: Gut) This study demonstrates that insults administered to the fetus can program altered sodium transport. Increased tubular sodium transport is a likely cause for the hypertension by prenatal programming. (Source: AJP: Regulatory, Integrative and Comparative Physiology) An environmentally friendly reflectometric method for bumetanide determination in pharmaceuticals. Authors: Pollo F, Sequinel R, Rufino JL, Los Weinert P, Pezza HR, Pezza L This paper describes a green analytical procedure for the determination of bumetanide using diffuse reflectance spectroscopy. The proposed method is based on reflectance measurements of a violet compound produced from a spot test reaction between bumetanide and p-dimethylaminocinnamaldehyde (p-DAC) in an acid medium, using filter paper as a solid support. The best conditions for the reaction have been found by experimental design methodologies. All reflectance measurements were carried out at 525 nm, and the linear range was from 1.37 x 10(-4) to 1.37 x 10(-3) mol L(-1), with a correlation coefficient of 0.998. The detection limit was estimated to be 3.98 x 10(-5) mol L(-1). Five commercial medicines containing b... Abstract The colon of the brushtail possum does not have an electrogenic secretory response. Given the functional significance of electrogenic Cl− secretion in the intestine of eutherian mammals, we have investigated the secretory response in the small intestine of this marsupial. In the Ussing chamber cAMP-dependent secretagogues stimulated a sustained increase in ileal short-circuit current (Isc), whereas Ca2+-dependent secretagogues induced a transient increase. Both the responses were inhibited by mucosal addition of the anion channel blocker 5-nitro-2-(3-phenylpropylamino) benzoic acid (100 μmol l−1), consistent with an anion secretory response. However, the responses were not inhibited by serosal bumetanide (10 μmol l−1) and were independent... We present a model for the control of the transmembrane potential of mammalian skeletal muscle cell. The model involves active and passive transport of Na(+), K(+), and Cl(-). As we check the model against experimental measurements on murine skeletal muscle cells, we find that the model can account for the observed bistability of the transmembrane potential at low extracellular potassium concentration. The effect of bumetanide, a blocker of the Na,K,2Cl-cotransporter, is measured and modeled. A hyperosmotic medium is known to stimulate the Na,K,2Cl-cotransporter and we also measure and model the effects of such a medium. Increased chloride transport has two effects on the interval along the extracellular potassium concentration axis where the system is bistable: the interval is shifted tow... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Authors: Chao PC, Hamilton KL Previously, we demonstrated that genistein stimulated Cl(-) secretion in the mouse jejunum (Baker and Hamilton, Am. J. Physiol. Cell Physiol. 287:C1636-C1645, 2004); however, the mode of action of genistein still remains unclear. Here, we examined the activation of Cl(-) secretion by the modulation of phosphodiesterases (PDEs) by genistein (75 microM) in the mouse jejunum with the Ussing short circuit current (Isc) technique. Drugs tested included theophylline (10 mM) a non-specific PDE inhibitor; 8-MM-IBMX (100 microM), EHNA (40 microM), milrinone (100 microM) and rolipram (40 and 100 microM), which are specific inhibitors of PDE1 - PDE4, respectively. Theophylline stimulated a bumetanide sensitive Isc, indicative of Cl(-) secretion, and abolished geniste... The airway surface liquid (ASL) is the thin fluid layer lining airway surface epithelial cells, whose volume and composition are tightly regulated and may be abnormal in cystic fibrosis (CF). We synthesized a two-color fluorescent dextran to measure ASL [K+], TAC-Lime-dextran-TMR, consisting of a green-fluorescing triazacryptand K+ ionophore-Bodipy conjugate, coupled to dextran, together with a red fluorescing tetramethylrhodamine reference chromophore. TAC-Lime-dextran-TMR fluorescence was K+-selective, increasing >4-fold with increasing [K+] from 0 to 40 mm. In well differentiated human airway epithelial cells, ASL [K+] was 20.8 ± 0.3 mm and decreased by inhibition of the Na+/K+ pump (ouabain), ENaC (amiloride), CF transmembrane conductance regulator (CFTRinh-172), or K+ channe... We report that bumetanide, a NKCC1 antagonist, reduces driving force of GABA-mediated currents (DFGABA) in neonatal hippocampal neurons and blocks the giant depolarizing potentials (GDPs), a spontaneous pattern of network activity. In the preparation composed of two intact interconnected hippocampi, bumetanide did not prevent generation of kainate-induced seizures, their propagation to the contralateral hippocampus, and formation of an epileptogenic mirror focus. However, in the isolated mirror focus, bumetanide effectively blocked spontaneous epileptiform activity transforming it to the GDP-like activity pattern. Bumetanide partially reduced DFGABA and therefore the excitatory action of GABA in epileptic neurons. Therefore bumetanide is a potent anticonvulsive agent although it cannot pre... Authors: Lam TI, Wise PM, O'Donnell ME Blood-brain barrier (BBB) Na transporters are essential for brain water and electrolyte homeostasis. However, they also contribute to edema formation during the early hours of ischemic stroke through increased transport of Na from blood into brain across an intact BBB. We have shown previously that a luminal BBB Na-K-Cl cotransporter is stimulated by hypoxia, aglycemia and arginine vasopressin (AVP), and that inhibition of the cotransporter by intravenous bumetanide significantly reduces edema and infarct in the rat middle cerebral artery occlusion (MCAO) model of stroke. More recently we have found evidence that intravenous cariporide (HOE-642), a highly potent Na/H exchange inhibitor, also reduces brain edema after MCAO. The present study was co... GABAA Receptors Mediate Excitation in Adult Rat GnRH Neurons. In this study, we investigated the GABA-induced changes in [Ca(2+)]i of GnRH neurons from GnRH-EGFP rats both to confirm the depolarizing action of GABA and to further examine the developmental and estrous cycle-dependent modulations of GABA action. GABA increased [Ca(2+)]i in GnRH neurons in all developmental stages of both sexes. GABA also increased [Ca(2+)]i in adult female GnRH neurons prepared in the afternoon at each estrous cycle stage. The percentages of neurons with increased [Ca(2+)]i were 90% in proestrus, 59% in estrus, 84% in diestrus I, and 89% in diestrus II. In GnRH neurons prepared from adult females in the morning, however, the percentage was significantly lower than in those prepared in the afternoon except in estrus. The percentage was also lower in adult males than in ... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. CONCLUSIONS: In conclusion, the analyzed immunosuppressive drugs had no direct and immediate influence on gastrointestinal function in therapeutic concentrations. However, toxic concentrations of mycophenolate mofetil, enteric coated MPA, and everolimus might be of importance for local effects on small bowel function due to oral application.<br /> <br /> <br /> PMID: 19487793 [PubMed - in process] (Source: Annals of Transplantation) Inhibitory actions of the gamma-aminobutyric acid in pediatric Sturge-Weber syndrome The mechanisms of epileptogenesis in Sturge-Weber syndrome (SWS) are unknown. We explored the properties of neurons from human pediatric SWS cortex in vitro and tested in particular whether gamma-aminobutyric acid (GABA) excites neurons in SWS cortex, as has been suggested for various types of epilepsies.Patch-clamp and field potential recordings and dynamic biphoton imaging were used to analyze cortical tissue samples obtained from four 6- to 14-month-old pediatric SWS patients during surgery.Neurons in SWS cortex were characterized by a relatively depolarized resting membrane potential, as was estimated from cell-attached recordings of N-methyl-D-aspartate channels. Many cells spontaneously fired action potentials at a rate proportional to the level of neuronal depolarization. The revers... Insulin resistance is associated with hypertension by mechanisms likely involving the kidney. To determine how the major apical sodium transporter of the thick ascending limb, the bumetanide-sensitive Na-K-2Cl cotransporter (NKCC2) is regulated by high-fat feeding, we treated young male, Fischer 344 X Brown Norway (F344BN) rats for 8 wk with diets containing either normal (NF, 4%) or high (HF, 36%) fat, by weight, primarily as lard. HF-fed rats had impaired glucose tolerance, increased urine excretion of 8-isoprostane (a marker of oxidative stress), increased protein levels for NKCC2 (50–125%) and the renal outer medullary potassium channel (106%), as well as increased natriuretic response to furosemide (20–40%). To test the role of oxidative stress in this response, in study 2... Low salt concentrations activate AMP-activated protein kinase in mouse macula densa cells The energy-sensing kinase AMP-activated protein kinase (AMPK) is associated with the sodium-potassium-chloride cotransporter NKCC2 in the kidney and phosphorylates it on a regulatory site in vitro. To identify a potential role for AMPK in salt sensing at the macula densa, we have used the murine macula densa cell line MMDD1. In this cell line, AMPK was rapidly activated by isosmolar low-salt conditions. In contrast to the known salt-sensing pathway in the macula densa, AMPK activation occurred in the presence of either low sodium or low chloride and was unaffected by inhibition of NKCC2 with bumetanide. Assays using recombinant AMPK demonstrated activation of an upstream kinase by isosmolar low salt. The specific calcium/calmodulin-dependent kinase kinase inhibitor STO-609 failed to suppre... -Aminobutyric acid type A (GABAA) receptors, a family of Cl--permeable ion channels, mediate fast synaptic inhibition as postsynaptically enriched receptors for -aminobutyric acid at GABAergic synapses. Here we describe an alternative type of inhibition mediated by GABAA receptors present on neocortical glutamatergic nerve terminals and examine the underlying signaling mechanism(s). By monitoring the activity of the presynaptic CaM kinase II/synapsin I signaling pathway in isolated nerve terminals, we demonstrate that GABAA receptor activation correlated with an increase in basal intraterminal [Ca2+]i. Interestingly, this activation of GABAA receptors resulted in a reduction of subsequent depolarization-evoked Ca2+ influx, which thereby led to an inhibition of glutamate release. To investi... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Authors: Zhou X, Smith SS The alpha4 subunit of the GABA(A) receptor (GABAR) is capable of rapid plasticity, increased by chronic exposure to positive GABA modulators, such as the neurosteroid 3alpha-OH-5alpha[beta]-pregnan-20-one (THP). Here, we show that 48 h exposure of differentiated neuroblastoma cells (IMR-32) to 100 nM THP increases alpha4 expression, without changing the current density or the concentration-response curve. Increased expression of alpha4-containing GABAR was verified by a relative insensitivity of GABA (EC(20))-gated current to modulation by the benzodiazepine (BZ) lorazepam (0.01 - 100 muM), and potentiation of current by flumazenil and RO15-4513, characteristic of alpha4betagamma2 pharmacology. In contrast to THP, compounds which decrease GABA-gated current, s... Authors: Asano J, Niisato N, Nakajima KI, Miyazaki H, Yasuda M, Iwasaki Y, Hama T, Dejima K, Hisa Y, Marunaka Y We investigated regulatory mechanisms of Cl- secretion playing an essential role in maintenance of surface fluid in human airway epithelial Calu-3 cells. The present study reports that quercetin (a flavonoid) stimulated bumetanide-sensitive Cl- secretion with reduction of apical Cl- conductance, suggesting that quercetin stimulates Cl- secretion by activating an entry step of Cl- across the basolateral membrane through Na(+)/K(+)/2Cl(-) cotransporter (NKCC1). To clarify the stimulatory mechanism of NKCC1 by quercetin, we verified involvement of PKA, PKC, PTK and cytosolic Ca2+-dependent pathways. A PKA inhibitor (PKI-14-22 amide), a PKC inhibitor (Gö 6983) or with a Ca2+... Bumetanide inhibits rapid kindling in neonatal rats. Discussion: The obtained results provide further evidence that bumetanide may be beneficial for treating neonatal seizures, and that NKCC1 represents a potential target for antiepileptic interventions in the immature brain. PMID: 19260939 [PubMed - as supplied by publisher] (Source: Epilepsia) Authors: Holtug K, Laverty G, Arnason SS, Skadhauge E Experiments were designed to characterize an active, electrogenic transport of NH(4)(+) ions across the colonic epithelium of the domestic fowl (Gallus gallus). Colonic segments were isolated and stripped of underlying muscle. The mucosal epithelia were mounted in Ussing chambers and voltage-clamped to measure the short-circuit currents (I(SC)) associated with transport. Bilateral addition of NH(4)(+) caused a dose-dependent outward current (negative I(SC)), with a Km of 34+8 mM and a maximal current response of 311+47 microA cm(-2) (12+2 microEq cm(-2) h(-1)). A similar effect was seen with unilateral addition of NH(4)(+) to the serosal (s) side, but not with mucosal (m) addition. Pre-treatment with 10(-4) M amiloride exposed a net... HCO (3) (-) -dependent volume regulation in alpha-cells of the rat endocrine pancreas. Authors: Davies SL, Best L, Brown PD Ion transport activity in pancreatic alpha-cells was assessed by studying cell volume regulation in response to anisotonic solutions. Cell volume was measured by a video imaging method, and cells were superfused with either 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid-buffered or HCO (3) (-) -buffered solutions. alpha-Cells did not exhibit a regulatory volume increase (RVI) in response to cell shrinkage caused by hypertonic solutions. A RVI was observed, however, in cells that had first undergone a regulatory volume decrease (RVD), but only in HCO (3) (-) -buffered solutions. RVI was also observed in response to a HCO (3) (-) -buffered hypertonic solution in which the glucose concentration was increased from 4 to 20 mM. The post-RVD RVI and th... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. F.D.A. Finds ‘Natural’ Diet Pills Laced With Drugs The Food and Drug Administration says the weight-loss capsules StarCaps contain a potent pharmaceutical drug called bumetanide, which can have serious side effects. (Source: NYT) Dangerous Secret in Diet Pills The Food Drug Administration says the weight-loss capsules StarCaps contain a potent pharmaceutical drug called bumetanide, which can have serious side effects. (Source: NYT > Health) Authors: Lee EA, Cho JH, Choi IS, Nakamura M, Park HM, Lee JJ, Lee MG, Choi BJ, Jang IS Although glycine receptors are found in most areas of the brain, including the hippocampus, their functional significance remains largely unknown. In the present study, we have investigated the role of presynaptic glycine receptors on excitatory nerve terminals in spontaneous glutamatergic transmission. Spontaneous EPSCs (sEPSCs) were recorded in mechanically dissociated rat dentate hilar neurons attached with native presynaptic nerve terminals using a conventional whole-cell patch recording technique under voltage-clamp conditions. Exogenously applied glycine or taurine significantly increased the frequency of sEPSCs in a concentration-dependent manner. This facilitatory effect of glycine was block... Authors: Riazi S, Tiwari S, Sharma N, Rash A, Ecelbarger CM Insulin resistance is associated with hypertension by mechanisms likely involving the kidney. To determine how the major apical sodium transporter of the thick ascending limb (TAL), the bumetanide-sensitive Na-K-2Cl cotransporter (NKCC2) is regulated by high-fat feeding, we treated young male, Fisher 344 X Brown Norway (F344BN) rats for 8 weeks with diets containing either normal- (NF, 4%) or high- (HF, 36%) fat, by weight, primarily as lard. HF-fed rats had impaired glucose tolerance, increased urine excretion of 8-isoprostane (a marker of oxidative stress), increased protein levels for NKCC2 (50-125%) and the renal outer medullary potassium channel (ROMK, 106%), as well as, increased natriuretic response to furosemide (20-40... The multi-herbal drug STW 5 (Iberogast®) has prosecretory action in the human intestine Abstract There is growing evidence that STW 5 (Iberogast®, fixed combination of hydroethanolic herbal extracts), besides being effective in functional dyspepsia, also improves symptoms in irritable bowel syndrome (IBS). Clinical data indicate that modulation of mucosal secretion is a promising approach to treat intestinal disorders associated with IBS. We therefore explored the effect of STW 5 on secretion in the human intestine and the mechanisms by which it acts. The Ussing chamber technique was used to measure mucosal secretion in human intestinal mucosa/submucosa preparations and in human epithelial cell line T84. In addition, we recorded STW 5 effects on human enteric neurons with voltage sensitive dye imaging. In human tissue and T84 cells STW 5 induced a dose-dependent increase in ... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Low salt concentrations activate AMP-activated protein kinase in mouse macula densa cells. Authors: Cook N, Fraser SA, Katerelos M, Katsis F, Gleich K, Mount PF, Steinberg GR, Levidiotis V, Kemp BE, Power DA The energy-sensing kinase AMP-activated protein kinase (AMPK) is associated with the sodium co-transporter NKCC2 in the kidney, and phosphorylates it on a regulatory site in vitro. To identify a potential role for AMPK in salt sensing at the macula densa, we have used the murine macula densa cell line MMDD1. In this cell line, AMPK was rapidly activated by iso-osmolar low salt conditions. In contrast to the known salt-sensing pathway in the macula densa, AMPK activation occurred in the presence of either low sodium or low chloride, and was unaffected by inhibition of NKCC2 with bumetanide. Assays using recombinant AMPK demonstrated activation of an upstream kinase by iso... Polycystic kidney diseases result from disruption of the genetically defined program that controls the size and geometry of renal tubules. Cysts which frequently arise from the collecting duct (CD) result from cell proliferation and fluid secretion. From mCCDcl1 cells, a differentiated mouse CD cell line, we isolated a clonal subpopulation (mCCD-N21) that retains morphogenetic capacity. When grown in three-dimensional gels, mCCD-N21 cells formed highly organized tubular structures consisting of a palisade of polarized epithelial cells surrounding a cylindrical lumen. Subsequent addition of cAMP-elevating agents (forskolin or cholera toxin) or of membrane-permeable cAMP analogs (CPT-cAMP) resulted in rapid and progressive dilatation of existing tubules, leading to the formation of cystlike ... -Aminobutyric acid type A (GABAA) receptor activation inhibits many primary afferent neurons by depolarization and increased membrane conductance. Deterministic (step and sinusoidal) functions are commonly used as stimuli to test such inhibition. We found that when the VS-3 mechanosensory neurons innervating the spider lyriform slit-sense organ were stimulated by randomly varying white-noise mechanical or electrical signals, their responses to GABAA receptor agonists were more complex than the inhibition observed during deterministic stimulation. Instead, there was rapid excitation, then brief inhibition, followed by long-lasting excitation. During the final excitatory phase, VS-3 neuron sensitivity to high-frequency signals increased selectively and their linear information capacity also ... Authors: Koltsova SV, Kotelevtsev SV, Tremblay J, Hamet P, Orlov SN Bumetanide and other high-ceiling diuretics (HCD) attenuate myogenic tone and contractions of vascular smooth muscle cells (VSMC) triggered by diverse stimuli. HCD outcome may be mediated by their interaction with NKCC1, the only isoform of Na(+), K(+), 2Cl(-) cotransporter expressed in VSMC as well as with targets distinct from this carrier. To examine these hypotheses, we compared the effect of bumetanide on contractions of mesenteric arteries from wild-type and NKCC1 knockout mice. In mesenteric arteries from wild-type controls, 100muM bumetanide evoked a decrease of up to 4-fold in myogenic tone and contractions triggered by modest [K(+)](o)-induced depolarization, phenylephrine and UTP. These actions of bumetanide... To Depolarize or Hyperpolarize? At the Axon Initial Segment, EGABA Sets the Stage GABAergic Depolarization of the Axon Initial Segment in Cortical Principal Neurons Is Caused by the Na-K-2Cl Cotransporter NKCC1. Khirug S, Yamada J, Afzalov R, Voipio J, Khiroug L, Kaila K. J Neurosci. 2008;28(18):4635[ndash]4639. GABAergic terminals of axo-axonic cells (AACs) are exclusively located on the axon initial segment (AIS) of cortical principal neurons, and they are generally thought to exert a powerful inhibitory action. However, recent work (Szabadics et al., 2006) indicates that this input from AACs can be depolarizing and even excitatory. Here, we used local photolysis of caged GABA to measure reversal potentials (EGABA) of GABAA receptor-mediated currents and to estimate the local chloride concentration in the AIS compared with other cellular compartments in dentate granul... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. After epididymal maturation, sperm capacitation, which encompasses a complex series of molecular events, endows the sperm with the ability to fertilize an egg. This process can be mimicked in vitro in defined media, the composition of which is based on the electrolyte concentration of the oviductal fluid. It is well established that capacitation requires Na+, HCO3-, Ca2+, and a cholesterol acceptor; however, little is known about the function of Cl– during this important process. To determine whether Cl–, in addition to maintaining osmolarity, actively participates in signaling pathways that regulate capacitation, Cl– was replaced by either methanesulfonate or gluconate two nonpermeable anions. The absence of Cl– did not affect sperm viability, but capacitation-asso... The transcription factor, tonicity-responsive enhancer binding protein (TonEBP), is involved in the adaptive response against hypertonicity. TonEBP regulates the expression of genes that catalyze the accumulation of osmolytes, and its transcriptional activity is increased by hypertonicity. The goal of the present investigation was to investigate whether cell shrinkage or high intracellular ionic concentration induced the activation of TonEBP. We designed a model system for isotonically shrinking cells over a prolonged period of time. Cells swelled in hypotonic medium and performed a regulatory volume decrease. Upon return to the original isotonic medium, cells shrank initially, followed by a regulatory volume increase. To maintain cell shrinkage, the RVI process was inhibited as follows: e... Authors: Montesano R, Ghzili H, Carrozzino F, Rossier BC, Feraille E Polycystic kidney diseases result from disruption of the genetically defined program that controls the size and geometry of renal tubules. Cysts which frequently arise from the collecting duct (CD) result from cell proliferation and fluid secretion. From mCCDcl1 cells, a differentiated mouse CD cell line, we isolated a clonal subpopulation (mCCD-N21) that retains morphogenetic capacity. When grown in three-dimensional gels, mCCD-N21 cells formed highly organized tubular structures consisting of a palisade of polarized epithelial cells surrounding a cylindrical lumen. Subsequent addition of cAMP-elevating agents (forskolin or cholera toxin) or membrane-permeable cAMP analogues (CPT-cAMP) resulted in rapid and progressi... Ammonium-evoked alterations in intracellular sodium and pH reduce glial glutamate transport activity The clearance of extracellular glutamate is mainly mediated by pH- and sodium-dependent transport into astrocytes. During hepatic encephalopathy (HE), however, elevated extracellular glutamate concentrations are observed. The primary candidate responsible for the toxic effects observed during HE is ammonium (NH4+/NH3). Here, we examined the effects of NH4+/NH3 on steady-state intracellular pH (pHi) and sodium concentration ([Na+]i) in cultured astrocytes in two different age groups. Moreover, we assessed the influence of NH4+/NH3 on glutamate transporter activity by measuring D-aspartate-induced pHi and [Na+]i transients. In 20-34 days in vitro (DIV) astrocytes, NH4+/NH3 decreased steady-state pHi by 0.19 pH units and increased [Na+]i by 21 mM. D-Aspartate-induced pHi and [Na+]i transients... Brain edema and the consequent increase in intracranial pressure and brain herniation are major complications of acute liver failure (fulminant hepatic failure) and a major cause of death in this condition. Ammonia has been strongly implicated as an important factor, and astrocyte swelling appears to be primarily responsible for the edema. Ammonia is known to cause cell swelling in cultured astrocytes, although the means by which this occurs has not been fully elucidated. A disturbance in one or more of these systems may result in loss of ion homeostasis and cell swelling. In particular, activation of the Na-K-Cl cotransporter (NKCC1) has been shown to be involved in cell swelling in several neurological disorders. We therefore examined the effect of ammonia on NKCC activity and its potent... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Starcaps Dietary Supplement Capsules Recall due to undeclared drug, Bumetanide, resulting in drug interactions including risk of hypotension (low blood pressure), or fainting (syncope). (Source: FDA MedWatch) Intracellular pH regulation on human Sertoli cells: role of membrane transporters. Authors: Oliveira PF, Sousa M, Barros A, Moura T, Rebelo da Costa A Sertoli cells are responsible for regulating a wide range of processes that lead to the differentiation of male germ cells into spermatozoa. Intracellular pH (pHi) is an important parameter in cell physiology regulating namely cell metabolism and differentiation. However, pHi regulation mechanisms in Sertoli cells have not yet been systematically elucidated. In this work, pHi was determined using in primary cultures of human Sertoli cells. Sertoli cells were exposed to weak acids which caused a rapid acidification of the intracellular milieu. pHi then recovered by a mechanism that was shown to be particularly sensitive to the presence of the inhibitor DIDS. In the presence of Amiloride and PSA, pHi recovery was also si... The Role of Chloride Channels in Rat Corpus Cavernosum: In Vivo Study Conclusions. Our findings suggest that chloride channels play an important role in the regulation of corpus cavernous smooth muscle tone in vivo. Chung S-D, Kuo Y-C, Liu S-P, Chang H-C, Yu H-J, and Hsieh J-T. The role of chloride channels in rat corpus cavernosum: In vivo study. J Sex Med **;**:**[ndash]**. (Source: The Journal of Sexual Medicine) Inhibition of chloride outward transport by gadolinium in cultured rat spinal cord neurons. Authors: Ishibashi H, Hirao K, Yamaguchi J, Nabekura J Gadolinium is a rare-earth lanthanide metal ion and is used as organic gadolinium complexes in magnetic resonance imaging (MRI). Although gadolinium-based MRI agents are thought to be safe in clinical use, the in vivo release of the toxic free inorganic gadolinium (Gd(3+)) has been reported in some patients with kidney disease. In central nervous system neurons, the inhibitory action of GABA is a consequence of relatively hyperpolarized Cl(-) equilibrium potential (E(Cl)), which results from the activity of K(+)-Cl(-) co-transporter (KCC). The lanthanide ions are reported to affect GABA(A) receptors. However, little is known about the effect of Gd(3+) on GABA(A) receptor function with intact intracellular Cl(-) concentration. In th... Authors: Rødgaard T, Schou K, Friis MB, Hoffmann EK The transcription factor, tonicity-responsive enhancer binding protein (TonEBP), is involved in the adaptive response against hypertonicity. TonEBP regulates the expression of genes that catalyze the accumulation of osmolytes, and its transcriptional activity is increased by hypertonicity. The goal of the present investigation was to investigate whether cell shrinkage or high intracellular ionic concentration induced the activation of TonEBP. We designed a model system for isotonically shrinking cells over a prolonged period of time. Cells swelled in hypotonic medium and performed a regulatory volume decrease (RVD). Upon return to the original isotonic medium, cells shrank initially followed by a regulatory volume increase (RVI).... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. When It Comes to GABAergic Responses and Neonatal Seizures—Sex Matters! Dissociated Gender-Specific Effects of Recurrent Seizures on GABA Signaling in CA1 Pyramidal Neurons: Role of GABAA Receptors. Galanopoulou AS. J Neurosci 2008;28(7):1557[ndash]1567. Early in development, the depolarizing GABAAergic signaling is needed for normal neuronal differentiation. It is shown here that hyperpolarizing reversal potentials of GABAAergic postsynaptic currents (EGABA) appear earlier in female than in male rat CA1 pyramidal neurons because of increased potassium chloride cotransporter 2 (KCC2) expression and decreased bumetanide-sensitive chloride transport in females. Three episodes of neonatal kainic acid-induced status epilepticus (3KA-SE), each elicited at postnatal days 4 (P4)[ndash]P6, reverse the direction of GABAAergic responses in both sexes. In males, 3KA-SE t... Abstract An electrogenic K+ transport in the tormogen cell of insect chemosensilla is involved in the generation and maintenance of the transepithelial potential (TEP). To gain more information about the K+ transport system underlying the TEP generation and the location of its components in the plasma membrane of the tormogen cell, we studied the effects of inhibitors of K+/H+ P-ATPase (bafilomycin A1, omeprazole and Na-orthovanadate), of K+/Cl− co-transport (bumetanide), of Cl− channels (NPPB) and of a K+ channel blocker (BaCl2). The relationship between TEP amplitude and spike firing activity was also studied. Experiments were performed on the labellar chemosensilla of the blowfly Protophormia terraenovae using a modified tip-recording technique. Results show that: (a) ... Authors: Jing Y, Dowdy JA, Van Scott MR, Fedan JS The isolated, perfused trachea preparation has been used to compare reactivity of the intact airway in response to differential exposure of the mucosal (intraluminal) and serosal (extraluminal) surfaces to contractile and relaxant agonists and other agents, and to gain insight into the modulatory role of the epithelium and the pathways involved. The apparatus has also been configured for simultaneous measurement of transepithelial potential difference and changes in tracheal diameter, thereby providing parallel observations of epithelial and smooth muscle function and reactivity to drugs. The transepithelial potential difference is a product of transepithelial resistance and short circuit current, and the present study describes a novel... The role of cation-dependent chloride transporters in neuropathic pain following spinal cord injury This study investigated the role of two major intracellular Cl- regulatory proteins, Na+-K+-Cl- cotransporter 1 (NKCC1) and K+-Cl- cotransporter 2 (KCC2), in neuropathic pain following spinal cord injury (SCI). Sprague-Dawley rats underwent a contusive SCI at T9 using the MASCIS impactor. The rats developed hyperalgesia between days 21 and 42 post-SCI. Thermal hyperalgesia (TH) was determined by a decrease in hindpaw thermal withdrawal latency time (WLT) between days 21 and 42 post-SCI. Rats with TH were then treated with either vehicle (saline containing 0.25% NaOH) or NKCC1 inhibitor bumetanide (BU, 30mg/kg, i.p.) in vehicle. TH was then re-measured at 1 h post-injection. Administration of BU significantly increased the mean WLT in rats (p < 0.05). The vehicle alone administration group ... Rational Polypharmacy: When Two Old Drugs Are Better Than One Bumetanide Enhances Phenobarbital Efficacy in a Neonatal Seizure Model. Dzhala VI, Brumback AC, Staley KJ. Ann Neurol 2008;63(2):222[ndash]235. OBJECTIVES: High levels of expression of the Na+-K+-2Cl[minus] (NKCC1) cotransporter in immature neurons cause the accumulation of intracellular chloride and, therefore, a depolarized Cl[minus] equilibrium potential (ECl). This results in the outward flux of Cl[minus] through GABAA channels, the opposite direction compared with mature neurons, in which GABAA receptor activation is inhibitory because Cl[minus] flows into the cell. This outward flow of Cl[minus] in neonatal neurons is excitatory and contributes to a greater seizure propensity and poor electroencephalographic response to GABAergic anticonvulsants such as phenobarbital and benzodiazepi... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Renal Na+-K+-Cl- cotransporter activity and vasopressin-induced trafficking are lipid raft-dependent Apical bumetanide-sensitive Na+-K+-2Cl– cotransporter (NKCC2), the kidney-specific member of a cation-chloride cotransporter superfamily, is an integral membrane protein responsible for the transepithelial reabsorption of NaCl. The role of NKCC2 is essential for renal volume regulation. Vasopressin (AVP) controls NKCC2 surface expression in cells of the thick ascending limb of the loop of Henle (TAL). We found that 40–70% of Triton X-100-insoluble NKCC2 was present in cholesterol-enriched lipid rafts (LR) in rat kidney and cultured TAL cells. The related Na+-Cl– cotransporter (NCC) from rat kidney was distributed in LR as well. NKCC2-containing LR were detected both intracellularly and in the plasma membrane. Bumetanide-sensitive transport of NKCC2 as analyzed by 86Rb+ in... Authors: Kahle KT, Staley KJ Seizures that occur during the neonatal period do so with a greater frequency than at any other age, have profound consequences for cognitive and motor development, and are difficult to treat with the existing series of antiepileptic drugs. During development, gamma-aminobutyric acid (GABA)ergic neurotransmission undergoes a switch from excitatory to inhibitory due to a reversal of neuronal chloride (Cl()) gradients. The intracellular level of chloride ([Cl()](i)) in immature neonatal neurons, compared with mature adult neurons, is about 20-40 mM higher due to robust activity of the chloride-importing Na-K-2Cl cotransporter NKCC1, such that the binding of GABA to ligand-gated GABA(A) receptor-associated Cl() channels triggers Cl() efflux and depolarizing ex... Rational polypharmacy: when two old drugs are better than one. Authors: Mathews GC BUMETANIDE ENHANCES PHENOBARBITAL EFFICACY IN A NEONATAL SEIZURE MODEL: Dzhala VI, Brumback AC, Staley KJ. Ann Neurol2008632:222-23517918265 OBJECTIVES: High levels of expression of the Na(+)-K(+)-2Cl(-) (NKCC1) cotransporter in immature neurons cause the accumulation of intracellular chloride and, therefore, a depolarized Cl(-) equilibrium potential (E(Cl)). This results in the outward flux of Cl(-) through GABA(A) channels, the opposite direction compared with mature neurons, in which GABA(A) receptor activation is inhibitory because Cl(-) flows into the cell. This outward flow of Cl(-) in neonatal neurons is excitatory and contributes to a greater seizure propensity and poor electroencephalographic response to GABAergic anticonvulsants such as phenobarbital and b... Excitatory GABA in Rodent Developing Neocortex In Vitro In this study, we used noninvasive single N-methyl-d-aspartate and GABA channel recordings in rodent brain slices to measure both Em and EGABA in the same neuron. We show that GABA strongly depolarizes pyramidal neurons and interneurons in both deep and superficial layers of the immature neocortex (P2–P10). However, GABA generates action potentials in layer 5/6 (L5/6) but not L2/3 pyramidal cells, since L5/6 pyramidal cells have more depolarized resting potentials and more hyperpolarized Vthr. The excitatory GABA transiently drives oscillations generated by L5/6 pyramidal cells and interneurons during development (P5–P12). The NKCC1 co-transporter antagonist bumetanide strongly reduces [Cl–]i, GABA-induced depolarization, and network oscillations, confirming the importanc... We report that application of 4-aminopyridine (4-AP) to immature (P6–P9) neocortical slices generates layer-specific interictal seizures (IISs) that transform after recurrent seizures to ictal seizures (ISs). During IISs, cell-attached recordings show action potentials in interneurons and pyramidal cells in L5/6 and interneurons but not pyramidal neurons in L2/3. However, L2/3 pyramidal neurons also fire during ISs. Using single N-methyl-d-aspartate (NMDA) channel recordings for measuring the cell resting potential (Em), we show that transition from IISs to ISs is associated with a gradual Em depolarization of L2/3 and L5/6 pyramidal neurons that enhances their excitability. Bumetanide, a NKCC1 co-transporter antagonist, inhibits generation of IISs and prevents their transformation t... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Airway epithelial Na-K-2Cl (NKCC1) cotransport is activated through hormonal stimulation and hyperosmotic stress via a protein kinase C (PKC) -mediated intracellular signaling pathway. Down-regulation of PKC prevents activation of NKCC1 expressed in Calu-3 cells. Previous studies of this signaling pathway identified coimmunoprecipitation of PKC with SPAK (Ste20-related proline alanine-rich kinase). We hypothesize that endogenous PKC activates SPAK, which subsequently activates NKCC1 through phosphorylation. Double-stranded silencing RNA directed against SPAK reduced SPAK protein expression by 65.8% and prevented increased phosphorylation of NKCC1 and functional activation of NKCC1 during hyperosmotic stress, measured as bumetanide-sensitive basolateral to apical 86Rb flux. Using recombinan... Ureter obstruction alters expression of renal acid-base transport proteins in rat kidney Urinary tract obstruction impairs renal function and is often associated with a urinary acidification defect caused by diminished net H+ secretion and/or HCO3– reabsorption. To identify the molecular mechanisms of these defects, protein expression of key acid-base transporters were examined along the renal nephron and collecting duct of kidneys from rats subjected to 24-h bilateral ureteral obstruction (BUO), 4 days after release of BUO (BUO-R), or BUO-R rats with experimentally induced metabolic acidosis (BUO-A). Semiquantitative immunoblotting revealed that BUO caused a significant reduction in the expression of the type 3 Na+/H+ exchanger (NHE3) in the cortex (21 ± 4%), electrogenic Na+/HCO3– cotransporter (NBC1; 71 ± 5%), type 1 bumetanide-sensitive Na+-K+-2Cl... EP(4) and EP(2) Receptor Subtypes Involved in Colonic Secretion in Rat. In conclusion, compilation of the results on induced SCC by subtype specific receptor agonists for EP receptors and the pattern of induced SCCs inhibited by GW627368X indicate the EP(4) receptor subtype as the major mediator of PGE(2)-induced electrogenic ion secretion with a lesser induction through the EP(2) receptor subtype. PMID: 18684231 [PubMed - as supplied by publisher] (Source: Basic and Clinical Pharmacology and Toxicology) Adult primary afferent neurons are depolarized by GABA throughout their entire surface, including their somata located in dorsal root ganglia (DRG). Primary afferent depolarization (PAD) mediated by GABA released from spinal interneurons determines presynaptic inhibition, a key mechanism in somatosensory processing. The depolarization is due to Cl– efflux through GABAA channels; the outward Cl– gradient is generated by a Na+,K+,2Cl– cotransporter (NKCC) as first established in amphibians. Using fluorescence imaging microscopy we measured [Cl–]i and cell water volume (CWV) in dissociated rat DRG cells (P0–P21) loaded with N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide and calcein, respectively. Basal [Cl–]i was 44.2 ± 1.2 mM (mean ± S... Cerebral Blood Flow and Cerebral Edema in Rats with Diabetic Ketoacidosis. CONCLUSIONS: These data demonstrate that CE in DKA is accompanied by cerebral hypoperfusion before treatment and suggest that blocking Na-K-Cl cotransport may reduce cerebral cell swelling. PMID: 18633109 [PubMed - as supplied by publisher] (Source: Diabetes) MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Authors: Torres ML, Ortega F, Cuaranta I, González J, Sanchez-Armass S The Na(+)/H(+) exchanger has been the only unequivocally demonstrated H(+)-transport mechanism in the synaptosomal preparation. We had previously suggested that a Cl(-)-H(+) symporter (in its acidifying mode) is involved in cytosolic pH regulation in the synaptosomal preparation. Supporting this suggestion, we now show that: (1) when synaptosomes are transferred from PSS to either gluconate or sulfate solutions, the Fura-2 ratio remains stable instead of increasing as it does in 50 mM K solution. This indicates that these anions do not promote a plasma membrane depolarization. (2) Based in the recovery rate from the cytosolic alkalinization, the anionic selectivity of the Cl(-)-H(+) symporter is NO (3) (-) >... Collecting duct cells swell when exposed to arginine vasopressin (AVP) in the presence of a transepithelial osmolality gradient. We investigated the mechanisms of AVP-induced cell swelling in isolated, perfused rat inner medullary collecting ducts (IMCDs) using quantitative video microscopy and fluorescence-based measurements of transepithelial water transport. We tested the roles of transepithelial water flow, basolateral solute entry, and the cytoskeleton (actomyosin). When a transepithelial osmolality gradient was imposed by addition of NaCl to the bath, AVP significantly increased both water flux and cell height. When the osmolality gradient was imposed by addition of mannitol, AVP increased water flux but not cell height, suggesting that AVP-induced cell swelling requires a NaCl gradi... Diuretics: from classical carbonic anhydrase inhibitors to novel applications of the sulfonamides. Authors: Supuran CT The widely clinically used benzothiadiazines and high ceiling diuretics, such as hydrochlorothiazide, hydroflumethiazide, quinethazone, metolazone, chlorthalidone, indapamide, furosemide and bumetanide, contain SO(2)NH(2) moieties acting as an effective zinc-binding function in carbonic anhydrases (CAs, EC 4.2.1.1) inhibitors. These drugs were launched in a period when only isoform CA II was known and considered physiologically/pharmacologically relevant. Although acting as moderate-weak inhibitors of CA II, all these drugs considerably inhibit other CA isozymes known nowadays to be involved in critical physiologic processes, among the 16 CAs present in vertebrates. Some low nanomolar (or even subnanomolar) inhibitors against such isoforms were recently detected, su... Conclusions: Our findings suggest that blocking of NKCC1 in albino visual cortex neurons could improve processing in visual cortex and therefore might be beneficial for vision in albinos. (Source: BioMed Central) Renal na-k-cl cotransporter activity and vasopressin-induced trafficking are lipid raft-dependent. RENAL NA-K-CL COTRANSPORTER ACTIVITY AND VASOPRESSIN-INDUCED TRAFFICKING ARE LIPID RAFT-DEPENDENT. Am J Physiol Renal Physiol. 2008 Jun 25; Authors: Welker P, Boehlick A, Mutig K, Salanova M, Kahl T, Schlueter H, Blottner D, Ponce-Coria J, Gamba G, Bachmann S Apical bumetanide-sensitive Na(+)-K(-)-2Cl(-)-cotransporter (NKCC2), the kidney-specific member of a cation-chloride cotransporter superfamily, is an integral membrane protein responsible for the transepithelial reabsorption of NaCl. The role of NKCC2 is essential for renal volume regulation. Vasopressin (AVP) controls NKCC2 surface expression in cells of the thick ascending limb of the loop of Henle (TAL). We found that 40-70% of Triton X-100-insoluble NKCC2 was present in cholesterol-enriched lipid rafts (LR) in rat kidn... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Alterations in EGF receptor (EGFR) signaling occur in intestinal disorders associated with dysregulated epithelial transport. In the present study, we investigated a role for the EGFR in the chronic regulation of intestinal epithelial secretory function. Epithelial Cl– secretion was measured as changes in short-circuit current (Isc) across voltage-clamped monolayers of T84 cells in Ussing chambers. Acute treatment of T84 cells with EGF (100 ng/ml, 15 min) chronically enhanced Isc responses to a broad range of secretagogues. This effect was apparent within 3 h, maximal by 6 h, and sustained for 24 h after treatment with EGF. The Na+/K+/2Cl– cotransporter (NKCC1) inhibitor bumetanide (100 µM) abolished the effect of EGF, indicating increased responses are due to potentiated... Effect of basolateral adenosine triphosphate on chloride secretion by bovine oviductal epithelium. Authors: Keating N, Quinlan LR The composition of the fluid within the oviduct is largely determined by the secretory and absorptive activities of the oviduct epithelium. The present study explored the effects of basolateral nucleotide stimulation on ion transport in the bovine oviduct using the chamber short-circuit current technique. Basolateral application of ATP induced a rapid transient increase in ion secretion by oviduct epithelial monolayers in a concentration-dependent manner. The ATP-induced short-circuit current (I(SC)) response was preserved in the presence of amiloride, whereas it was reduced in the absence of extracellular chloride or in the presence of bumetanide. The channels underlying the chloride secretory response were identified as Ca(2+)-activated Cl(-) channels a... Ureter obstruction alters expression of renal acid-base transport proteins in rat kidney. Authors: Wang G, Li C, Kim SW, Ring T, Wen J, Djurhuus JC, Wang W, Nielsen S, Frokiaer J Urinary tract obstruction impairs renal function and is often associated with a urinary acidification defect caused by diminished net H(+) secretion and/or HCO3(-) reabsorption. To identify the molecular mechanisms of these defects, protein expression of key acid-base transporters were examined along the renal nephron and collecting duct of kidneys from rats subjected to 24-h bilateral ureteral obstruction (BUO), 4 days after release of BUO (BUO-R), or BUO-R rats with experimentally induced metabolic acidosis (BUO-A). Semiquantitative immunoblotting revealed that BUO caused significant reductions in the expression of type 3 Na(+)/H(+) exchanger (NHE3) in the cortex (21 +/- 4%), electrogenic Na(+)/ ... Suggestions for Drug Monitoring in Adults in Primary Care Source: London and South East Regional Medicines Information Service Area: Evidence > Drug Monitoring This document has been produced as a collaboration between London and South East Medicines Information Service, South West Medicines Information Service and Croydon Primary Care Trust. It outlines UK published recommendations for monitoring safety parameters for a range of medicines that may be prescribed for adults in primary care and highlights areas where local consensus is required to address discrepancies or gaps. The information is presented in terms of monitoring required at baseline, during initiation, during maintenance, actions required when faced with an abnormal result, other relevant information, and BNF-listed significant drug interactions. The drugs covered include: amiod... Iron accumulation in bronchial epithelial cells is dependent on concurrent sodium transport. Authors: Turi JL, Piantadosi CA, Stonehuerner JD, Ghio AJ Airway epithelial cells prevent damaging effects of extracellular iron by taking up the metal and sequestering it within intracellular ferritin. Epithelial iron transport is associated with transcellular movement of other cations including changes in the expression or activity of Na, K-ATPase and epithelial Na(+) channel (ENaC). Given this relationship between iron and Na(+), we hypothesized that iron uptake by airway epithelial cells requires concurrent Na(+) transport. In preliminary studies, we found that Na(+)-free buffer blocked iron uptake by human airway epithelial cell. Na(+) channels inhibitors, including furosemide, bumetanide, and ethylisopropyl amiloride (EIPA) significantly decreased epithelial cell concentrations o... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. In this study, we explored the mechanisms of three specific cotransporters known to play a role in the hypoxic state: KB-R7943 for blockade of the Na+/Ca2+ exchanger, bumetanide for the Na+-K+-2Cl– cotransporter, and amiloride for Na+/H+ cotransporters. In vivo measurements of arteriolar diameter and [NO] at normal and locally reduced oxygen tension in the rat parietal cortex provided the functional analysis. As previously found for intestinal arterioles, bumetanide-sensitive cotransporters are primarily responsible for sensing reduced oxygen because the increased [NO] and dilation were suppressed. The Na+/Ca2+ exchanger facilitated increased NO formation because blockade also suppressed [NO] and dilatory responses to decreased oxygen. Amiloride-sensitive Na+/H+ cotransporters did no... Chronic candesartan alters expression and activity of NKCC2, NCC, and ENaC in the obese Zucker rat The obese Zucker rat reportedly has increased activity of the intrarenal renin-angiotensin-aldosterone system, which conceptually could contribute to elevated salt sensitivity and blood pressure (BP). Our aim was to determine whether there was increased angiotensin II type 1 receptor (AT1R)-mediated upregulation of expression or activity of the bumetanide-sensitive Na-K-2Cl cotransporter, the thiazide-sensitive Na-Cl cotransporter (NCC), and/or the epithelial sodium channel (ENaC) in obese vs. lean Zucker rats. Male obese and lean Zucker rats (10-wk old) were fed either 1) control chow (1% NaCl) or 2) chow with candesartan (CAN), an AT1R antagonist (25 mg/kg·diet) for 14 wk (n = 8/treatment/body type). BP measured by radiotelemetry, was markedly reduced by CAN (~20–25 mmHg) in... Genetic causes of hypercalciuric nephrolithiasis Abstract Renal stone disease (nephrolithiasis) affects 3–5% of the population and is often associated with hypercalciuria. Hypercalciuric nephrolithiasis is a familial disorder in over 35% of patients and may occur as a monogenic disorder that is more likely to manifest itself in childhood. Studies of these monogenic forms of hypercalciuric nephrolithiasis in humans, e.g. Bartter syndrome, Dent’s disease, autosomal dominant hypocalcemic hypercalciuria (ADHH), hypercalciuric nephrolithiasis with hypophosphatemia, and familial hypomagnesemia with hypercalciuria have helped to identify a number of transporters, channels and receptors that are involved in regulating the renal tubular reabsorption of calcium. Thus, Bartter syndrome, an autosomal disease, is caused by mutati... Authors: Chou CL, Yu MJ, Kassai EM, Morris RG, Hoffert JD, Wall SM, Knepper MA Collecting duct cells swell when exposed to arginine vasopressin (AVP) in the presence of a transepithelial osmolality gradient. We investigated the mechanisms of AVP-induced cell swelling in isolated perfused rat inner medullary collecting ducts (IMCDs) using quantitative video microscopy and fluorescence-based measurements of transepithelial water transport. We tested the roles of transpepithelial water flow, basolateral solute entry, and the cytoskeleton (actomyosin). When a transepithelial osmolality gradient was imposed by addition of NaCl to the bath, AVP significantly increased both water flux and cell height. When the osmolality gradient was imposed by addition of mannitol, AVP increased water flux b... [Epileptiform activities generated in vitro by human temporal lobe tissue.] Authors: Huberfeld G, Clemenceau S, Cohen I, Pallud J, Wittner L, Navarro V, Baulac M, Miles R Drug-resistant partial epilepsies, including temporal lobe epilepsies with hippocampal sclerosis and cortical dysplasias, offer the opportunity to study human epileptic activity in vitro since the preferred therapy often consists of the surgical removal of the epileptogenic zone. Slices of this tissue retain functional neuronal networks and may generate epileptic activity. The properties of cells in this tissue do not seem to be significantly changed, but excitatory synaptic characteristics are enhanced and GABAergic inhibition is preserved. Typically, epileptic activity is not generated spontaneously by the neocortex, whether dysplastic or not, but can be induced by convulsants. The initiati... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. This study is consistent with renal nerves playing a role in mediating the hypertension by prenatal programming by dexamethasone. Key words: prenatal programming, thiazide sensitive cotransporter, NHE3, bumetanide sensitive cotransporter. PMID: 18400872 [PubMed - as supplied by publisher] (Source: Am J Physiol Renal P...) Authors: O'Mahony F, Toumi F, Mroz MS, Ferguson G, Keely SJ Alterations in epidermal growth factor receptor (EGFr) signaling occur in intestinal disorders associated with dysregulated epithelial transport. In the present study we investigated a role for the EGFr in chronic regulation of intestinal epithelial secretory function. Epithelial Cl(-) secretion was measured as changes in Isc across voltage-clamped monolayers of T84 cells in Ussing chambers. Acute treatment of T84 cells with EGF (100 ng/ml; 15 min) chronically enhanced Isc responses to a broad range of secretagogues. This effect was apparent within 3 hrs, maximal by 6 hrs, and sustained for 24 hrs after treatment with EGF. The Na(+)/K(+)/2Cl(-) cotransporter (NKCC1) inhibitor, bumetanide (100 microM), abolished the effect of E... Authors: Temperini C, Cecchi A, Scozzafava A, Supuran CT Diuretics such as hydrochlorothiazide, hydroflumethiazide, quinethazone, metolazone, chlorthalidone, indapamide, furosemide, and bumetanide containing primary sulfamoyl moieties were reevaluated as inhibitors of 12 human carbonic anhydrases (hCAs, EC 4.2.1.1). These drugs considerably inhibit (low nanomolar range) some CA isozymes involved in critical physiologic processes, among the 16 present in vertebrates, for example, metholazone against CA VII, XII, and XIII, chlorthalidone against CA VB, VII, IX, XII, and XIII, indapamide against CA VII, IX, XII, and XIII, furosemide against CA I, II, and XIV, and bumethanide against CA IX and XII. The X-ray crystal structure of the hCA II-indapamide adduct was also resolved at high resolu... Apparent intermediate K conductance channel hyposmotic activation in human lens epithelial cells This study explores the nature of K fluxes in human lens epithelial cells (LECs) in hyposmotic solutions. Total ion fluxes, Na-K pump, Cl-dependent Na-K-2Cl (NKCC), K-Cl (KCC) cotransport, and K channels were determined by 85Rb uptake and cell K (Kc) by atomic absorption spectrophotometry, and cell water gravimetrically after exposure to ouabain ± bumetanide (Na-K pump and NKCC inhibitors), and ion channel inhibitors in varying osmolalities with Na, K, or methyl-d-glucamine and Cl, sulfamate, or nitrate. Reverse transcriptase polymerase chain reaction (RT-PCR), Western blot analyses, and immunochemistry were also performed. In isosmotic (300 mosM) media ~90% of the total Rb influx occurred through the Na-K pump and NKCC and ~10% through KCC and a residual leak. Hyposmotic media (150... Sympathetic stimulation induces weak salivation compared with parasympathetic stimulation. To clarify this phenomenon in salivary glands, we investigated cAMP-induced modulation of Ca2+-activated Cl– secretion from rat parotid and submandibular acinar cells because fluid secretion from salivary glands depends on the Cl– secretion. Carbachol (Cch), a Ca2+-increasing agent, induced hyperpolarization of the cells with oscillatory depolarization in the current clamp mode of the gramicidin-perforated patch recording. In the voltage clamp mode at –80 mV, Cch induced a bumetanide-sensitive oscillatory inward current, which was larger in rat submandibular acinar cells than in parotid acinar cells. Forskolin and IBMX, cAMP-increasing agents, did not induce any marked current, but ... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Chronic Candesartan alters expression and activity of NKCC2, NCC, and ENaC in the obese Zucker Rat. Authors: Halagappa VK, Tiwari S, Riazi S, Hu X, Ecelbarger CM The obese Zucker rat reportedly has increased activity of the intra-renal renin-angiotensin-aldosterone system (RAAS), which conceptually could contribute to elevated salt-sensitivity and blood pressure (BP). Our aim was to determine whether there was increased angiotensin II type I receptor (AT1R)-mediated upregulation of expression or activity of the bumetanide-sensitive Na-K-2Cl cotransporter (NKCC2), the thiazide-sensitive Na-Cl cotransporter (NCC), and/or the epithelial sodium channel (ENaC) in obese versus lean Zucker rats. Male obese and lean Zucker rats (10-weeks old) were fed either: 1) control chow (1% NaCl) or 2) chow with candesartan (CAN), an AT1R antagonist (25 mg/kg∙diet) for 14 weeks (n = 8/treatmen... Ammonium transport in the colonic crypt cell line, T84: role for Rhesus glycoproteins and NKCC1 Although colonic lumen NH4+ levels are high, 15–44 mM normal range in humans, relatively few studies have addressed the transport mechanisms for NH4+. More extensive studies have elucidated the transport of NH4+ in the kidney collecting duct, which involves a number of transporter processes also present in the distal colon. Similar to NH4+ secretion in the renal collecting duct, we show that the distal colon secretory model, T84 cell line, has the capacity to secrete NH4+ and maintain an apical-to-basolateral NH4+ gradient. NH4+ transport in the secretory direction was supported by basolateral NH4+ loading on NKCC1, Na+-K+-ATPase, and the NH4+ transporter, RhBG. NH4+ was transported on NKCC1 in T84 cells nearly as well as K+ as determined by bumetanide-sensitive 86Rb-uptake. 86Rb-upt... Page: 18 (Source: Inpharma Weekly) (Source: Inpharma) Escherichia coli EAST1 toxin toxicity of variants 17-2 and O 42. Authors: Veilleux S, Holt N, Schultz BD, Dubreuil JD EAST1 (EnteroAggregative heat-Stable Toxin 1) is a 4.1kDa toxin that was first detected in the enteroaggregative Escherichia coli (EAEC) strain 17-2 (O3:H2) isolated from the stools of a Chilean child with diarrhoea. Accordingly, EAST1 is thought to play a role in the pathogenicity of EAEC. The goal of this study was to obtain purified biologically active forms of two EAST1 variants (17-2 and O 42). Purified toxin samples were treated with protein disulfide isomerase (PDI) to ascertain the integrity of the disulfide bridges. Since EAST1 is often compared to STa (heat-Stable Toxin a), both purified EAST1 variants were tested for biological activity using the suckling mouse assay, the reference test for STa. A positive gut to body (G/B... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Hypoxia effects on cell volume and ion uptake of cerebral microvascular endothelial cells Increased transport of Na across an intact blood-brain barrier (BBB) contributes to cerebral edema formation in ischemic stroke. Our previous studies have shown that ischemic factors stimulate activity of a luminal BBB Na-K-Cl cotransporter, and we have hypothesized that during ischemia, the cotransporter together with the abluminal Na/K pump mediates increased transport of Na from blood into the brain. However, it is possible that elevated Na-K-Cl cotransporter activity could also cause cell swelling if it outpaces ion efflux pathways. The present study was conducted to evaluate the effects of hypoxia on intracellular volume of BBB cells. Cerebral microvascular endothelial cell (CMEC) monolayers were exposed to varying levels of hypoxia for 1 to 5 h in an O2-controlled glove box, and cell... Authors: Shintani T, Hirono C, Sugita M, Iwasa Y, Shiba Y Sympathetic stimulation induces weak salivation compared with parasympathetic stimulation. To clarify this phenomenon in salivary glands, we investigated cAMP-induced modulation of Ca(2+)-activated Cl(-) secretion from rat parotid and submandibular acinar cells because fluid secretion from salivary glands depends on the Cl(-) secretion. Carbachol (CCh), a Ca(2+)-increasing agent, induced hyperpolarization of the cells with oscillatory depolarization in the current clamp mode of the gramicidin-perforated patch recording. In the voltage clamp mode at -80 mV, CCh induced a bumetanide-sensitive oscillatory inward current, which was larger in rat submandibular acinar cells than in parotid acinar cells. Forskolin and IBMX (forskolin +... This study explores the nature of K fluxes in human lens epithelial cells (LECs) in hyposmotic solutions. Total ion fluxes, Na/K pump, Cl-dependent Na-K-2Cl (NKCC), K-Cl (KCC) cotransport and K channels were determined by (85)Rb uptake and cell K (Kc) by atomic absorption spectrophotometry, and cell water gravimetrically after exposure to ouabain +/- bumetanide (Na/K pump and NKCC inhibitors) and ion channel inhibitors in varying osmolalities with Na, K or methyl-D-glucamine and Cl, sulfamate or nitrate. Reverse transcriptase polymerase chain reaction (RT-PCR), Western blots and immunochemistry were performed. Results show in isosmotic (300 mOsM) media ~90% of the total Rb influx occurred through Na/K pump and NKCC, ~ 10% through KCC and a residual leak. Hyposmotic media (150 mOsM) decreas... Rapid Hair Cell Loss: A Mouse Model for Cochlear Lesions Abstract In comparison to other mammals, mice have proved extremely resistant to aminoglycoside-induced hair cell ablation in vivo. In this paper we examine the pattern and extent of cochlear lesions rapidly induced with a combination of a single dose of aminoglycoside (kanamycin) followed by a loop diuretic (bumetanide). With this protocol, the vestibular system was unaffected, but in the cochlea, there was extensive loss of outer hair cells (OHC) that commenced in the basal coil and progressed apically so that, by 48 h, OHC loss was almost complete. TUNEL-positive nuclei and activated caspase-3 labeling demonstrated that most OHC died via a classical apoptotic pathway. However, scattered debris within the OHC region suggested that many apoptotic cells ruptured prior... Ammonium transport in the colonic crypt cell line, T84: Role for Rhesus Glycoproteins and NKCC1. Authors: Worrell RT, Merk L, Matthews JB Although colonic lumen NH4(+) levels are high, 15-44 mM normal range in humans, relatively few studies have addressed the transport mechanisms for NH4(+). More extensive studies have elucidated the transport of NH4(+) in the kidney collecting duct which involves a number of transporter processes also present in the distal colon. Similar to NH4(+) secretion in the renal collecting duct, we show that the distal colon secretory model, T84 cell line, has the capacity to secrete NH4(+) and maintain an apical to basolateral NH4(+) gradient. NH4(+) transport in the secretory direction was supported by basolateral NH4(+) loading on NKCC1, Na(+)/K(+)-ATPase, and the NH4(+) transporter, RhBG. NH4(+) was transported on NKCC1 in T84 cells nearly as well as ... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. pH stat studies on bicarbonate secretion in the isolated mouse ileum. This study examined HCO(3)(-) secretion in the ileum, since it is less understood than HCO(3)(-) secretion in other intestinal segments. Mouse ileal mucosa was mounted in vitro in Ussing chambers, and the mucosal alkalinization rate (J(OH)) was determined by pH stat titration, while the mucosal side was bathed with a buffer-free solution (100% O(2)) and the serosal side with a HCO(3)(-)/CO(2)-buffered solution. The transmural potential difference (PD) was recorded. The mucosal alkalinization rate (J(OH)) was higher in the presence of mucosal Cl(-) than in its absence. Forskolin, an activator of adenylate cyclase, enhanced J(OH) and PD in both the presence and absence of mucosal Cl(-). Mucosal SO(4)(2-) also caused an increase in J(OH), although the magnitude was smaller than that induced b... Apical bumetanide-sensitive Na+-K+-2Cl- co-transporter, termed NKCC2, is the major salt transport pathway in kidney thick ascending limb. NKCC2 surface expression is subject to regulation by intracellular protein trafficking. However, the protein partners involved in the intracellular trafficking of NKCC2 remain unknown. Moreover, studies aimed at under-standing the post-translational regulation of NKCC2 have been hampered by the difficulty to express NKCC2 protein in mammalian cells. Here we were able to express NKCC2 protein in renal epithelial cells by tagging its N-terminal domain. To gain insights into the regulation of NKCC2 trafficking, we screened for interaction partners of NKCC2 with the yeast two-hybrid system, using the C-terminal tail of NKCC2 as bait. Aldolase B was identifie... Involvment of endogenous prostaglandin in emodin-evoked rat colonic anion secretion. Authors: Xu JD, Wang W, Li LS, Chen X, Zhu JX It has been reported that emodin is able to promote gastrointestinal motility and stimulate large intestinal water secretion; however, the mechanism is still not clear. The aim of the present study is to examine the effects of emodin on the rat colonic transepithelial ion transport and the underlying mechanism. The study was carried out by means of the short circuit current (I(SC)) recording. Basolateral application of emodin induced a concentration-dependent I(SC) increase, and the EC(50) was 76.0 mumol/l. Pretreatment with epithelial Na(+) channel blocker, amiloride (10 mumol/l), did not affect the I(SC) responses elicited by emodin, but removal of extracellular Cl(-) or apical pretreatment with Cl(-) channel blocker, glibenclamide (1 mmo... Clinical and Experimental Pharmacology and Physiology, Volume 34, Issue 12, Page 1307-1312, December 2007. SUMMARY 1. The renal bumetanide-sensitive Na–K–2Cl cotransporter (BSC-1) is expressed only in the thick ascending limb and selectively traffics from intracellular vesicles (IVs) to apical plasma membranes (PMs), where BSC-1 regulates sodium reabsorption. ... (Source: Clinical and Experimental Pharmacology and Physiology) Hypoxia Effects on Cell Volume and Ion Uptake of Cerebral Microvascular Endothelial Cells. Authors: Brillault J, Lam TI, Rutkowsky JM, Foroutan S, O'donnell ME Increased transport of Na across an intact blood-brain barrier (BBB) contributes to cerebral edema formation in ischemic stroke. Our previous studies have shown that ischemic factors stimulate activity of a luminal BBB Na-K-Cl cotransporter and we have hypothesized that during ischemia, the cotransporter together with the abluminal Na/K pump mediates increased transport of Na from blood into brain. However, it is possible that elevated Na-K-Cl cotransporter activity could also cause cell swelling if it outpaces ion efflux pathways. The present study was conducted to evaluate the effects of hypoxia on intracellular volume of BBB cells. Cerebral microvascular endothelial cell (CMEC) monolayers were exposed to varying le... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. In our quest to develop a tissue-engineered tear secretory system, we have tried to demonstrate active transepithelial ion fluxes across rabbit lacrimal acinar cell monolayers on polyester membrane scaffolds to evaluate the bioelectrical properties of the cultured cells. Purified lacrimal gland acinar cells were seeded onto polyester membrane inserts and cultured to confluency. Morphological properties of the cell monolayers were evaluated by transmission electron microscopy and immunofluorescence staining for Na+,K+-ATPase and the tight junction-associated protein occludin. Sections revealed cell monolayers with well-maintained epithelial cell polarity, i.e., presence of apical (AP) secretory granules, microvilli, and junctional complexes. Na+,K+-ATPase was localized on both the basal-lat... [Cl ]i modulation of Ca2+-regulated exocytosis in ACh-stimulated antral mucous cells of guinea pig In conclusion, a decrease in [Cl–]i accelerates ATP-dependent priming and [Ca2+]i increase, which enhance Ca2+-regulated exocytosis in ACh-stimulated antral mucous cells. (Source: AJP: Gastrointestinal and Liver Physiology) Bumetanide enhances phenobarbital efficacy in a neonatal seizure model High levels of expression of the Na+-K+-2Cl- (NKCC1) cotransporter in immature neurons cause the accumulation of intracellular chloride and, therefore, a depolarized Cl- equilibrium potential (ECl). This results in the outward flux of Cl- through GABAA channels, the opposite direction compared with mature neurons, in which GABAA receptor activation is inhibitory because Cl- flows into the cell. This outward flow of Cl- in neonatal neurons is excitatory and contributes to a greater seizure propensity and poor electroencephalographic response to GABAergic anticonvulsants such as phenobarbital and benzodiazepines. Blocking the NKCC1 transporter with bumetanide prevents outward Cl- flux and causes a more negative GABA equilibrium potential (EGABA) in immature neurons. We therefore tested wheth... Characterization of a long-term rat mTAL cell line A medullary thick ascending limb (mTAL) cell line, termed raTAL, has been established from freshly isolated rat mTAL tubules and cultured continuously for up to 75 passages; it retains characteristics of mTAL cells even after retrieval from storage in liquid nitrogen for several months. The cells express Tamm-Horsfall glycoprotein (THP), a TAL-specific marker, grow to confluence, exhibit a polygonal morphology characteristic of epithelial cells, and form "domes." Detection of THP, Na+-K+-2Cl– cotransporter (NKCC2), Na+-K+-ATPase, and renal outer medullary K+ channel (ROMK) was achieved using indirect immunofluorescence and confocal microscopy. Western blot analysis of NKCC2 expression using two different antibodies revealed a band of ~160 kDa, and RT-PCR analysis demonstrated the pre... Colonic epithelial ion transport is not affected in patients with diverticulosis Conclusions: We conclude that epithelial ion transport is not significantly altered in patients with diverticulosis and that the MUAS chamber can be adapted for studies of human colonic endoscopic biopsies. (Source: BMC Gastroenterology) MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Clinical and Experimental Pharmacology and Physiology Volume 0, Issue 0, Page ???-???. SUMMARY 1. The renal bumetanide-sensitive Na–K–2Cl cotransporter (BSC-1) is expressed only in the thick ascending limb and selectively traffics from intracellular vesicles (IVs) to apical plasma membranes (PMs), where BSC-1 regulates sodium reabsorption. ... (Source: Clinical and Experimental Pharmacology and Physiology) CONCLUSION: In these MTAL cells the Ba(2+)-sensitive component of NH(4)(+) transport is predominant and consists of permeation of NH(4)(+) through an apical ROMK-related channel. PMID: 17570948 [PubMed - indexed for MEDLINE] (Source: Nephron Physiology) E-Ring Isoprostanes Stimulate a Cl- Conductance in Airway Epithelium via EP Prostanoid Receptors. We examined the electrophysiological responses evoked by several different isoprostane species in bovine airway epithelium using the Ussing chamber technique. The E-ring isoprostanes 15-E1t-IsoP and 15-E2t-IsoP evoked a substantial increase in short-circuit current (ISC), whereas four different F-ring isomers were ineffective. 15-E2t-IsoP-evoked ISC was mimicked by the EP-agonist PGE2, but not by agonists of EP1/EP3-, FP- or TP-receptors (sulprostone, fluprostenol and U46619, respectively). On the other hand, this response was significantly reduced by the EP4-receptor blocker GW627386 but not by blockers of various other prostanoid receptors (ICI 192,605 [TP-selective]; SC19220 [EP1-selective]; AH6809 [DP/EP1/EP2-selective]; AL8810 [FP-selective]). 15-E2t-IsoP-evoked ISC was reduced by blo... [Cl-]i modulation of Ca2+-regulated exocytosis in ACh-stimulated antral mucous cells of guinea pig. In conclusion, a decrease in [Cl(- )]i accelerates ATP-dependent priming and [Ca(2+ )]i increase, which enhance Ca(2+ )-regulated exocytosis in ACh-stimulated antral mucous cells. Key words: gastric antrum, mucin exocytosis, intracellular Cl- cincentration, acetylcholine, cell volume. PMID: 17673548 [PubMed - as supplied by publisher] (Source: Am J Physiol Gastroi...) Appearance of segmental discrepancy of anion transport in rat distal colon. In conclusion, the rat distal colon manifests a segmental discrepancy in anion transport stimulated by luminal forskolin. HCO(3)(-) might be predominantly involved in the forskolin-induced anion secretion in DC(1), but Cl(-) might be the main component of the anion secretion in DC(4). PMID: 17666794 [PubMed - in process] (Source: Biological and Pharmaceutical Bulletin) MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. NKCC1 Does Not Accumulate Chloride in Developing Retinal Neurons GABA excites immature neurons due to their relatively high intracellular chloride concentration. This initial high concentration is commonly attributed to the ubiquitous chloride cotransporter NKCC1, which uses a sodium gradient to accumulate chloride. Here we tested this hypothesis in immature retinal amacrine and ganglion cells. Western blotting detected NKCC1 at birth and its expression first increased, then decreased to the adult level. Immunocytochemistry confirmed this early expression of NKCC1 and localized it to all nuclear layers. In the ganglion cell layer, staining peaked at P4 and then decreased with age, becoming undetectable in adult. In comparison, KCC2, the chloride extruder, steadily increased with age localizing primarily to the synaptic layers. For functional tests, we u... We searched the UK Medicines Information website, the BNF, TRIP and Medline databases but found very little robust information to answer this question. Lee et al examined whether presumed "sulfa allergy" in patients treated for intracranial hypertension with acetazolamide or furosemide resulted in a cross reaction. (Source: NLH Question Answering Service) Spinal NKCC1 blockade inhibits TRPV1-dependent referred allodynia Conclusions: Our findings indicate that spinal NKCC1 and TRPV1 are critical for referred allodynia mediated by a painful visceral stimulus. Moreover, they suggest that endogenous TRPV1 agonists, released in the CNS in painful conditions, might stimulate TRPV1 receptors on primary afferents that, in turn, play a role in increasing NKCC1 activity leading to allodynia. (Source: BioMed Central) Conclusions. These findings indicate that TSPO is located in mitochondrial membranes of HT-29 and reveal that its activation induces a rise in cytosolic Ca 2+ leading to the stimulation of Cl - secretion. PMID: 17561806 [PubMed - as supplied by publisher] (Source: Biology of the Cell) Electrogenic bicarbonate secretion by prairie dog gallbladder Pathological rates of gallbladder salt and water transport may promote the formation of cholesterol gallstones. Because prairie dogs are widely used as a model of this event, we characterized gallbladder ion transport in animals fed control chow by using electrophysiology, ion substitution, pharmacology, isotopic fluxes, impedance analysis, and molecular biology. In contrast to the electroneutral properties of rabbit and Necturus gallbladders, prairie dog gallbladders generated significant short-circuit current (Isc; 171 ± 21 µA/cm2) and lumen-negative potential difference (–10.1 ± 1.2 mV) under basal conditions. Unidirectional radioisotopic fluxes demonstrated electroneutral NaCl absorption, whereas the residual net ion flux corresponded to Isc. In response to 2 ... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. The strategies available for treating salivary gland hypofunction are limited because relatively little is known about the secretion process in humans. An initial microarray screen detected ion transport proteins generally accepted to be critically involved in salivation. We tested for the activity of some of these proteins, as well as for specific cell properties required to support fluid secretion. The resting membrane potential of human acinar cells was near –51 mV, while the intracellular [Cl–] was ~62 mM, about fourfold higher than expected if Cl ions were passively distributed. Active Cl– uptake mechanisms included a bumetanide-sensitive Na+-K+-2Cl– cotransporter and paired DIDS-sensitive Cl–/HCO3– and EIPA-sensitive Na+/H+ exchangers that correlat... Preventing Medical Errors: Preventing Drug Mix-Ups: Bumetanide and Norepinephrine The Institute for Safe Medication Practices is warning health care professionals about several recent mix-ups between two injectable drugs made by Bedford Laboratories: bumetanide, a diuretic, and norepinephrine, used to treat MI and hypotension. Th... (Source: Food and Drug Adminstration (FDA): Patient Safety News) Authors: Waseem TV, Kolos VA, Lapatsina LP, Fedorovich SV Neurotransmitter release is dependent on both calcium and sodium influx. Hypotonic swelling and hypertonic shrinking of neurons evokes calcium-independent exocytosis of neurotransmitters into the synaptic cleft. To date, there are not too much data available on relationship between extracellular osmolarity and sodium concentration in presynaptic endings. In the present study we investigated the effects of hypotonic swelling and hypertonic shrinking on sodium levels, as measured using fluorescent dyes SBFI-AM and Sodium Green in rat brain synaptosomes. Reduction of incubation medium osmolarity from 310 to 230mOsm did not raise the intrasynaptosomal sodium concentration. An increase of osmolarity from 310 to 810mOsm is accompanied... Shrinkage insensitivity of NKCC1 in myosin II-depleted cytoplasts from Ehrlich ascites tumor cells Protein phosphorylation/dephosphorylation and cytoskeletal reorganization regulate the Na+-K+-2Cl– cotransporter (NKCC1) during osmotic shrinkage; however, the mechanisms involved are unclear. We show that in cytoplasts, plasma membrane vesicles detached from Ehrlich ascites tumor cells (EATC) by cytochalasin treatment, NKCC1 activity evaluated as bumetanide-sensitive 86Rb influx was increased compared with the basal level in intact cells yet could not be further increased by osmotic shrinkage. Accordingly, cytoplasts exhibited no regulatory volume increase after shrinkage. In cytoplasts, cortical F-actin organization was disrupted, and myosin II, which in shrunken EATC translocates to the cortical region, was absent. Moreover, NKCC1 activity was essentially insensitive to the myosin... Effect of the Na-K-2Cl cotransporter NKCC1 on systemic blood pressure and smooth muscle tone Studies in rat aorta have shown that the Na-K-2Cl cotransporter NKCC1 is activated by vasoconstrictors and inhibited by nitrovasodilators, contributes to smooth muscle tone in vitro, and is upregulated in hypertension. To determine the role of NKCC1 in systemic vascular resistance and hypertension, blood pressure was measured in rats before and after inhibition of NKCC1 with bumetanide. Intravenous infusion of bumetanide sufficient to yield a free plasma concentration above the IC50 for NKCC1 produced an immediate drop in blood pressure of 5.2% (P < 0.001). The reduction was not prevented when the renal arteries were clamped, indicating that it was not due to a renal effect of bumetanide. Bumetanide did not alter blood pressure in NKCC1-null mice, demonstrating that it was acting specif... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Electrogenic Bicarbonate Secretion by Prairie Dog Gallbladder. Authors: Moser AJ, Gangopadhyay A, Bradbury NA, Peters KW, Frizzell RA, Bridges RJ Pathologic rates of gallbladder salt and water transport may promote the formation of cholesterol gallstones. Because prairie dogs are widely-used as a model of this event, we characterized gallbladder ion transport in animals fed control chow using electrophysiology, ion substitution, pharmacology, isotopic fluxes, impedance analysis, and molecular biology. In contrast to the electroneutral properties of rabbit and Necturus gallbladders, prairie dog gallbladders generated significant short-circuit current (Isc, 171 +/- 21 microA/cm(2)) and lumen negative potential difference (-10.1 +/- 1.2 mV) under basal conditions. Unidirectional radioisotopic fluxes demonstrated electroneutral NaCl absorption, while ... Na+-K+-Cl– cotransporter isoform 1 (NKCC1) and reverse mode operation of the Na+/Ca2+ exchanger (NCX) contribute to intracellular Na+ and Ca2+ overload in astrocytes following oxygen-glucose deprivation (OGD) and reoxygenation (REOX). Here, we further investigated whether NKCC1 and NCX play a role in mitochondrial Ca2+ (Cam2+) overload and dysfunction. OGD/REOX caused a doubling of mitochondrial-releasable Ca2+ (P < 0.05). When NKCC1 was inhibited with bumetanide, the mitochondrial-releasable Ca2+ was reduced by ~42% (P < 0.05). Genetic ablation of NKCC1 also reduced Cam2+ accumulation. Moreover, OGD/REOX in NKCC1+/+ astrocytes caused dissipation of the mitochondrial membrane potential (m) to 42 ± 3% of controls. In contrast, when NKCC1 was inhibited with bumetanide, dep... The Na+/K+/2Cl– cotransporter (NKCC) plays diverse roles in the kidney, contributing sodium reabsorption and tubuloglomerular feedback (TGF). However, NKCC is also expressed in smooth muscle and inhibitors of this transporter affect contractility in both vascular and nonvascular smooth muscle. In the present study, we investigated the effects of NKCC inhibitors on vasoconstrictor responses of the renal afferent arteriole using the in vitro perfused hydronephrotic rat kidney. This preparation has no tubules and no TGF, eliminating this potential complication. Furosemide and bumetanide inhibited myogenic responses in a concentration-dependent manner. Bumetanide was ~20-fold more potent (IC50 1.0 vs. 20 µmol/l). At 100 and 10 µmol/l, furosemide and bumetanide inhibited myoge... Conclusions: G lamblia infection causes epithelial barrier dysfunction owing to down regulation of the tight junction protein claudin 1 and increased epithelial apoptoses. Na+-dependent d-glucose absorption is impaired and active electrogenic anion secretion is activated. Thus, the mechanisms of diarrhoea in human chronic giardiasis comprise leak flux, malabsorptive and secretory components. (Source: Gut) Authors: Capó-Aponte JE, Wang Z, Bildin VN, Pokorny KS, Reinach PS The capacity of the corneal epithelium to adapt to hypertonic challenge is dependent on the ability of the cells to upregulate the expression and activity of cell membrane-associated Na-K-2Cl cotransporter1 (NKCC1). Yet, the signaling pathways that control this response during hypertonic stress are still unclear. We studied stress-induced changes in proliferation and survival capacity of SV40-immortalized human (HCEC) and rabbit (RCEC) corneal epithelial cells as a function of (i) the magnitude of the hypertonic challenge, (ii) differential changes in activation of mitogen-activated protein kinase (MAPK), and (iii) the extent of p38MAPK interaction with NKCC1. Cells were incubated in hypertonic (up to 600 mOsm) media f... MedWorm Message: Get the very latest Swine Flu news via the MedWorm Swine Flu RSS news feed - updated hourly from thousands of authoritative health and news sources. Authors: Ernest NJ, Sontheimer H Mammalian cells regulate their volume to prevent unintentional changes in intracellular signaling, cell metabolism, and DNA integrity. Intentional cell volume changes occur as cells undergo proliferation, apoptosis, or cell migration. To regulate cell volume, cells use channels and transport systems to flux osmolytes across the plasma membrane followed by the obli |