Na-K-ATPase protein is critical for maintaining cellular ion gradients and volume and for transepithelial ion transport in kidney and lung. Thyroid hormone, 3,3',5-triiodo-l-thyronine (T3), given for 2 days to adult rats, increases alveolar fluid resorption by 65%, but the mechanism is undefined. We tested the hypothesis that T3 stimulates Na-K-ATPase in adult rat alveolar epithelial cells (AEC...

Calcium binding at 0 degrees C to a purified sheep kidney Na+,K+-ATPase was described by linear Scatchard plots. Binding at saturating free calcium was 65-80 nmol/mg of protein, or 30-40 mol of calcium/mol of enzyme. Aqueous emulsions of lipids extracted from Na+,K+-ATPase yielded dissociation constants and maximum calcium-binding values that were similar to those for native Na+,K+-ATPase. Phos...

Nitric oxide (NO) reduces the molecular activity of Na+-K+-ATPase in opossum kidney (OK) cells, a proximal tubule cell line. In the present study, we investigated the cellular mechanisms for the inhibitory effect of NO on Na+-K+-ATPase. Sodium nitroprusside (SNP), a NO donor, inhibited Na+-K+-ATPase in OK cells, but not in LLC-PK1cells, another proximal tubule cell line. Similarly, phorbol 12-m...

NaCl loading and plasma volume expansion stimulate 2 natriuretic systems, vasoconstrictor, digitalis-like Na/K-ATPase inhibitors and vasorelaxant ANP peptides. Several hormones, including ANP, regulate activity of the Na/K-ATPase by modulation of its phosphorylation state. We studied effects of ANP on Na/K-ATPase phosphorylation and inhibition by an endogenous sodium pump ligand, marinobufageni...

A major difference between the Na,K-ATPase ion pump and other P-type ATPases is its ability to bind cardiotonic steroids such as ouabain. Na,K-ATPase also interacts with many membrane and cytosolic proteins. In addition to their role in Na,K-ATPase regulation, it became apparent that some of the newly identified interactions are capable of organizing the Na,K-ATPase into various signaling compl...

On the basis of our report that a glycolipoprotein fraction (GLP) extracted from Leptospira interrogans contains a potent inhibitor of renal Na,K-ATPase, we proposed that GLP-induced inhibition of Na,K-ATPase might be the primary cellular defect in the physiopathology of leptospirosis. The present study was designed to test this hypothesis by determining whether or not 1). GLP inhibits all the ...

The rapid activation of gill Na(+),K(+)-ATPase was analyzed in the mummichog (Fundulus heteroclitus) and Atlantic salmon (Salmo salar) transferred from low salinity (0.1 ppt) to high salinity (25-35 ppt). In parr and presmolt, Salmo salar gill Na(+),K(+)-ATPase activity started to increase 3 days after transfer. Exposure of Fundulus heteroclitus to 35 ppt seawater (SW) induced a rise in gill Na...

Stimulation of Na(+)/K(+)-ATPase translocation to the cell surface increases active Na(+) transport, which is the driving force of alveolar fluid reabsorption, a process necessary to keep the lungs free of edema and to allow normal gas exchange. Here, we provide evidence that insulin increases alveolar fluid reabsorption and Na(+)/K(+)-ATPase activity by increasing its translocation to the plas...

Malpighian tubule of Rhodnius sp. express two sodium pumps: the classical ouabain-sensitive (Na+ + K+)ATPase and an ouabain-insensitive, furosemide-sensitive Na+-ATPase. In insects, 5-hydroxitryptamine is a diuretic hormone released during meals. It inhibits the (Na+ + K+)ATPase and Na+ -ATPase activities indicating that these enzymes are involved in fluid secretion. Furthermore, in Rhodnius ne...

Mechanical ventilation with high tidal volumes (HV(T)) impairs lung liquid clearance (LLC) and downregulates alveolar epithelial Na-K-ATPase. We have previously reported that the Na-K-ATPase alpha(2)-subunit contributes to LLC in normal rat lungs. Here we tested whether overexpression of Na-K-ATPase alpha(2)-subunit in the alveolar epithelium would increase clearance in a HV(T) model of lung in...