To examine the effect of aldosterone on sarcolemmal Na+ transport, we measured ouabain-sensitive electrogenic Na+-K+pump current ( I p) in voltage-clamped ventricular myocytes and intracellular Na+ activity ([Formula: see text]) in right ventricular papillary muscles. Aldosterone (10 nM) induced an increase in both I p and the rate of rise of [Formula: see text] during Na+-K+pump blockade with ...

Na+-K+-2Cl- cotransporter has been suggested to contribute to active intracellular Cl- accumulation in neurons at both early developmental and adult stages. In this report, we extensively characterized the Na+-K+-2Cl- cotransporter in primary culture of cortical neurons that were dissected from cerebral cortex of rat fetus at embryonic day 17. The Na+-K+-2Cl- cotransporter was expressed abundan...

A detailed study of hypertonically stimulated Na-K-2Cl cotransport (NKCC1) in Xenopus laevis oocytes was carried out to better understand the 1 K(+):1 Cl(-) stoichiometry of transport that was previously observed. In this study, we derived the velocity equations for K(+) influx under both rapid equilibrium assumptions and combined equilibrium and steady-state assumptions and demonstrate that th...

Na-K-2Cl cotransport and Cl/[Formula: see text] exchange are prominent mechanisms for Cl- uptake in Cl--secreting epithelial cells. We used immunofluorescence microscopy to delineate the distributions of Na-K-2Cl cotransporter-1 (NKCC1) and anion exchanger-2 (AE2) proteins in rat gastric mucosa (zymogenic zone). Parietal cells (PCs) above the neck of the gastric gland contained abundant AE2 but...

Epinephrine and β-adrenergic agonists (β1 and β2 for isoproterenol, β1 for dobutamine, β2 for salbutamol) stimulated K+ (or86Rb) influx mediated by the Na+-K+-2Cl-cotransporter and the Na+-K+pump in isolated colonic crypt cells. Preincubation with bumetanide abolished the epinephrine effect on the Na+-K+pump, suggesting that the primary effect is on the cotransporter. Maximal effect was obtaine...

The antifungal antibiotic amphotericin B causes considerable toxic effects during clinical therapy. We have shown previously that amphotericin B-induced cytotoxicity and apoptosis were eradicated by the Na+, K+, 2Cl- cotransport inhibitor bumetanide. To elucidate the role of K+ flux and the activity of Na+, K+ ATPase and Na+, K+, 2Cl- cotransport in apoptosis and cytotoxicity induced by amphote...

Superoxide (O2-) enhances Na reabsorption by the thick ascending limb (THAL). Na absorption in this segment involves the Na-K-2Cl cotransporter, K channel, and Na-K-ATPase. We hypothesized that O2- stimulates NaCl absorption primarily by enhancing Na-K-2Cl cotransport. First, we measured steady-state intracellular Na (Nai) and chloride (Cli). Xanthine oxidase (XO; 0.75 mU/ml) and hypoxanthine (...

Our study addresses selected parameters of rat erythrocyte ion transport (Na(+)-K(+) pump, Na(+)-K(+)-2Cl- cotransport, and passive cation fluxes) after acute or chronic hypoxia exposure. We did not find any significant change of ion transport after acute hypoxia. However, chronic hypoxia could modify ion transport because the affinity of Na(+)-K(+) pump for intracellular Na(+) seems to be decr...

To identify protein kinases (PK) and phosphatases (PP) involved in regulation of the Na+-K+-2Cl-cotransporter in Ehrlich cells, the effect of various PK and PP inhibitors was examined. The PP-1, PP-2A, and PP-3 inhibitor calyculin A (Cal-A) was a potent activator of Na+-K+-2Cl-cotransport (EC50 = 35 nM). Activation by Cal-A was rapid (<1 min) but transient. Inactivation is probably due to a 10%...

McDaniel, Nichole, and Christian Lytle. Parietal cells express high levels of Na-K-2Cl cotransporter on migrating into the gastric gland neck. Am. J. Physiol. 276 (Gastrointest. Liver Physiol. 39): G1273–G1278, 1999.—Na-K-2Cl cotransport and Cl/HCO3 exchange are prominent mechanisms for Cl2 uptake in Cl2-secreting epithelial cells. We used immunofluorescence microscopy to delineate the distribu...