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A model of Na-K-2Cl cotransport based on ordered ion binding and glide symmetry.

In the duck red blood cell, Na-K-2Cl cotransport exhibits two modes of ion movement: net cotransport and obligate cation exchange. In high-K cells, the predominant exchange is K/K (or K/Rb). In high-Na cells, it becomes Na/Na (or Na/Li). Both represent partial reactions in which a fully loaded carrier releases part of its cargo, rebinds fresh ions, and returns back across the membrane fully loaded. Net cotransport occurs when the carrier unloads completely and returns empty. This mode has a fixed stoichiometry of 1Na:1K:2Cl under all conditions tested. The ion requirements of the two exchanges

Regulation of intracellular sodium in cultured rat hippocampal neurones.

1. We studied regulation of intracellular Na+ concentration ([Na+]i) in cultured rat hippocampal neurones using fluorescence ratio imaging o … ng activation of Na(+)-dependent Cl(-)-HCO3- exchange. Inhibition of Na(+)-K(+)-2Cl- cotransport by bumetanide had no effect on [Na+]i. 4. Brief, small changes in extracellular K+ concentration ([K+]o) influenced neuronal [Na+]i only weakly. Virtually no change in [Na+]i was observed with elevation or reduction of [K+]o by 1 mM. Only 30% of cells reacted to …

Efficacy and Safety of Intravenous Chlorothiazide versus Oral Metolazone in Patients with Acute Decompensated Heart Failure and Loop Diuretic Resistance.

STUDY OBJECTIVE: To assess the efficacy and safety of intravenous (IV) chlorothiazide versus oral metolazone when added to loop diuretics in patients with acute decompensated heart failure (ADHF) and loop diuretic resistance. DESIGN: Retrospective cohort study. SETTING: Large urban academic medical center. PATIENTS: Adults admitted with ADHF between 2005 and 2015 who had loop diuretic resistance, defined as administration of IV furosemide at a dose of 160 mg/day or higher (or an equivalent dose of IV bumetanide), during hospitalization, and who then received at least one dose of IV chloroth…

Down-regulation of Na-K-Cl cotransport by protein kinase C is mediated by protein phosphatase 1 in pigmented ciliary epithelial cells.

The role of protein phosphatases in the regulation of Na-K-Cl cotransport was examined in human pigmented ciliary epithelial (PE) cells. Both a 37 kDa form and a 72 kDa form of protein phosphatase 1 (PP1) could be immunologically detected. The protein phosphatase inhibitor calyculin A stimulated Na-K-Cl cotransport by 89 +/- 12% at 10 n M, whereas okadaic acid had no effect at concentrations less than 100 n M. Calyculin A had no significant effect on either Na-K ATPase or ouabain-insensitive, bumetanide-insensitive 86Rb+uptake. These data suggest that PP1 plays a role in the inhibition of Na-K…

Pharmacological and dietary-supplement treatments for autism spectrum disorder: a systematic review and network meta-analysis.

BACKGROUND: There is still no approved medication for the core symptoms of autism spectrum disorder (ASD). This network meta-analysis invest … SMD = 0.27 95% CI [0.09, 0.44], RB: 0.48 [0.26, 0.70]), atomoxetine (k = 3, RB:0.49 [0.18, 0.80]), bumetanide (k = 4, RB: 0.35 [0.09, 0.62], OCS: 0.61 [0.31, 0.91]), and risperidone (k = 4, SCM: 0.31 [0.06, 0.55], RB: 0.60 [0.29, 0.90]; k = 3, OCS: 1.18 [0.75, 1.61]) in children/adolescents; fluoxetine (k = 1, RB: 1.20 [0.45, 1.96]), fluvoxamine (k = 1, RB: …

Empagliflozin in Heart Failure: Diuretic and Cardiorenal Effects.

BACKGROUND: Sodium-glucose cotransporter-2 inhibitors improve heart failure-related outcomes. The mechanisms underlying these benefits are n … sodium, 1.2±0.7% versus 0.7±0.4%; P=0.001), and there was a synergistic effect in combination with bumetanide (fractional excretion of sodium, 5.8±2.5% versus 3.9±1.9%; P=0.001). At 14 days, the natriuretic effect of empagliflozin persisted, resulting in a reduction in blood volume (-208 mL [interquartile range, -536 to 153 mL] versus -14 mL [interquartile …

Rubidium-87 magnetic resonance spectroscopy and imaging for analysis of mammalian K+ transport.

This review summarizes results 87Rb MRS/I studies of K+ transport in mammalian cells, organs and in vivo. It provides a brief description of … mal areas and did not affect uptake in ischemic areas. Drugs that may affect passive Rb+ transport (bumetanide, pinacidil, glibenclamide) did not change Rb+ uptake either in the normal or ischemic zones. 87Rb-MRI was also able to localize ischemia and infarction in blood-perfused hearts. 87Rb MRS/I is an excellent non-invasive research tool for studies of K+ …

Crypt base cells show forskolin-induced Cl- secretion but no cation inward conductance.

Whole-cell patch-clamp studies in base cells of isolated colonic crypts of rats pretreated with dexamethasone were performed to examine the … sing concentrations of several loop diuretics were examined. Furosemide, piretanide, torasemide and bumetanide (up to 0.1-0.5 mmol/l) all hyperpolarized Vm, albeit only by less than 10 mV. Another subclass of loop diuretics containing a tetrazolate in position 1 [e.g. azosemide, no. 19A and no. 20A from Schlatter E, Greger R, Weidtke C (1983) Pflüger Arch 39 …

Calcium-sensing receptor inhibits secretagogue-induced electrolyte secretion by intestine via the enteric nervous system.

Bacterial toxins such as cholera toxin induce diarrhea by both direct epithelial cell generation of cyclic nucleotides as well as stimulation of the enteric nervous system (ENS). Agonists of the extracellular calcium-sensing receptor (CaSR) can reduce toxin-stimulated fluid secretion in ENS-absent colonic epithelial crypts by increasing phosphodiesterase-dependent cyclic-nucleotide degradation. Here we show that the CaSR is also highly expressed in tetrodotoxin (TTX)-sensitive neurons comprising the ENS, suggesting that CaSR agonists might also function through neuronal pathways. To test this

Isoforms of the Na-K-2Cl cotransporter in murine TAL II. Functional characterization and activation by cAMP.

The functional properties of alternatively spliced isoforms of the mouse apical Na+-K+-2Cl- cotransporter (mBSC1) were examined, using expression in Xenopus oocytes and measurement of 22Na+ or 86Rb+ uptake. A total of six isoforms, generated by the combinatorial association of three 5' exon cassettes (A, B, and F) with two alternative 3' ends, are expressed in mouse thick ascending limb (TAL) [see companion article, D. B. Mount, A. Baekgaard, A. E. Hall, C. Plata, J. Xu, D. R. Beier, G. Gamba, and S. C. Hebert. Am. J. Physiol. 276 (Renal Physiol. 45): F347-F358, 1999]. The two 3' ends predict

Deafness and imbalance associated with inactivation of the secretory Na-K-2Cl co-transporter.

Deafness can result from a variety of gene defects. Some genes involved in the physiology of hearing encode membrane transporters that regulate the ionic composition of the fluid bathing the inner ear. The endolymph is an extracellular fluid with an atypical composition that resembles the intracellular milieu, high in K+ and low in Na+. Recent studies have emphasized the prominent role of K+ channels in endolymph secretion and mechanical transduction. Coupled electroneutral transport of Na+, K+ and Cl- is mediated by two isoforms of the Na-K-2Cl co-transporter: the absorptive isoform BSC1 (als

Depressed cheek cell sodium transport in human hypertension.

Na+ transport activity was measured in cheek cells from untreated hypertensive subjects and age-matched normotensive controls identified from a blood pressure screening program. Cheek cells were isolated by a simple mouth wash procedure and Na+ transport activity was measured as the proton-dependent uptake of 22Na+ using a rapid filtration assay. The rate of Na+ uptake was about 45% lower in hypertensive subjects and this difference persisted in a follow up study 2 years later involving those subjects who remained untreated for their hypertension. The proton independent Na+ uptake was also red

Diuretic response in acute heart failure: clinical characteristics and prognostic significance.

AIM: Diminished diuretic response is common in patients with acute heart failure, although a clinically useful definition is lacking. Our aim was to investigate a practical, workable metric for diuretic response, examine associated patient characteristics and relationships with outcome. METHODS AND RESULTS: We examined diuretic response (defined as Δ weight kg/40 mg furosemide) in 1745 hospitalized acute heart failure patients from the PROTECT trial. Day 4 response was used to allow maximum differentiation in responsiveness and tailoring of diuretic doses to clinical response, following sensi

Chloride secretion in a morphologically differentiated human colonic cell line that expresses the epithelial Na+ channel.

Cell line models of colonic electrolyte transport have been extensively used despite lacking some of the characteristics of native tissue. While native colonic crypts absorb or secrete NaCl, immortalized cell lines only retain the secretory phenotype. In the present study we have characterized functionally and molecularly, vectorial fluid and electrolyte transport in the morphologically differentiated human colonic cell line LIM1863. LIM1863 cells form morphologically differentiated organoids resembling native human colonic crypts, which secrete fluid and electrolytes across the apical membran

Inhibition of enterotoxin-induced porcine colonic secretion by diarylsulfonylureas in vitro.

Muscle-stripped piglet colon was used to evaluate changes in short-circuit current (I(sc)) as an indicator of anion secretion. Mucosal exposure to Escherichia coli heat-stable (STa) or heat-labile enterotoxins (LT) stimulated I(sc) by 32 +/- 5 and 42 +/- 7 microA/cm(2), respectively. Enterotoxin-stimulated I(sc) was not significantly affected by either 4,4'-diaminostilbene-2, 2'-disulfonic acid or CdCl(2), inhibitors of Ca(2+)-activated Cl(-) channels and ClC-2 channels, respectively. Alternatively, N-(4-methylphenylsulfonyl)-N'-(4-trifluoromethylphenyl)urea (DASU-02), a compound that inhibits

Empagliflozin in Heart Failure: Regional Nephron Sodium Handling Effects.

SIGNIFICANCE STATEMENT: The effect of sodium-glucose cotransporter-2 inhibitors (SGLT2i) on regional tubular sodium handling is poorly under … on. Assessments were made with and without antagonism of sodium reabsorption through the loop using bumetanide. RESULTS: Empagliflozin resulted in a large decrease in sodium reabsorption in the PT (increase in FELi=7.5%±10.6%, P = 0.001), with several observations suggesting inhibition of PT sodium hydrogen exchanger 3. In the absence of renal compensation, …

Charybdotoxin blocks with high affinity the Ca-activated K+ channel of Hb A and Hb S red cells: individual differences in the number of channels.

We have investigated the effect of a purified preparation of Charybdotoxin (CTX) on the Ca-activated K+ (Ca-K) channel of human red cells (R … initial rates of net K+ efflux (90 mmol/liter cell K+) into Na+ medium containing glucose, ouabain, bumetanide at pH 7.4 were measured. Ca-K efflux increased in a sigmoidal fashion (n of Hill 1.8) when Ca2+ was raised, with a Km of 0.37 microM and saturating between 2 and 10 microM Ca2+. Ca-K efflux was partially blocked (71 +/- 7.8%, mean +/- SD, n = 17) by …

Ionic Plasticity: Common Mechanistic Underpinnings of Pathology in Spinal Cord Injury and the Brain.

The neurotransmitter GABA is normally characterized as having an inhibitory effect on neural activity in the adult central nervous system (CNS), which quells over-excitation and limits neural plasticity. Spinal cord injury (SCI) can bring about a modification that weakens the inhibitory effect of GABA in the central gray caudal to injury. This change is linked to the downregulation of the potassium/chloride cotransporter (KCC2) and the consequent rise in intracellular Cl- in the postsynaptic neuron. As the intracellular concentration increases, the inward flow of Cl- through an ionotropic GABA

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… Bumetanide decreased pain scores on several pain scales [ 100 ]. This therapeutic improvement was accompanied by increased KCC2 protein expression suggesting bumetanide drove improved GABAergic inhibition and that the shift in GABAergic inhibition improved pain symptoms [ 100 ]. … Eftekhari and colleagues found that NKCC1 inhibition with bumetanide could successfully reduce seizure frequency in adult patients with temporal lobe epilepsy [ 139 ]. More recent studies have confirmed bumetanide as a beneficial therapy for temporal lobe epilepsy in adults [ 140 ]. …

Propionate-induced epithelial K(+) and Cl(-)/HCO3(-) secretion and free fatty acid receptor 2 (FFA2, GPR43) expression in the guinea pig distal colon.

Propionate, a fermented product in the lumen of the large intestine, is a short-chain fatty acid (SCFA) known to have a variety of localized physiological and pathophysiological functions (e.g., luminal fluid secretion and anti-inflammatory response). In the present study, we investigated propionate-induced transepithelial ion transport and the expression of SCFA receptor, free fatty acid receptor 2 (FFA2, otherwise known as GPR43) in the guinea pig distal colon utilizing the Ussing chamber technique and immunohistochemistry. The addition of propionate to the luminal bathing solution concentra

Activation of chloride secretion via proteinase-activated receptor 2 in a human eccrine sweat gland cell line--NCL-SG3.

Proteinase-activated receptor 2 (PAR-2) has been shown to elicit secretion in a variety of secretory epithelial cells by the transepithelial movement of chloride ions across the apical membrane. However, it is not known whether these receptors are present and/or functional in the secretory epithelial cells of the human eccrine sweat gland. To investigate this possibility mRNA analysis, Ca2+ microspectrofluorimetry and the short circuit current (Isc) technique were used to quantify electrolyte transport in a cell line (NCL-SG3) derived from human eccrine sweat gland secretory epithelia. The res