We have used a gene transfer system to investigate the relationship between expression of the rat Na,K-ATPase alpha 1 subunit gene and ouabain-resistant Na,K-ATPase activity. A cDNA clone encoding the entire rat Na,K-ATPase alpha 1 subunit was inserted into the expression vector pSV2neo. This construct (pSV2 alpha 1) conferred resistance to 100 microM ouabain to ouabain-sensitive CV-1 cells. Hy...

Ion pump, Na,K-ATPase specifically binds cardiotonic steroids (CTS), which leads to inhibition of the enzyme activity and activation of signaling network in the cell. We have studied interaction of Na,K-ATPase with CTS of two different types - marinobufagenin and ouabain. We have shown that both CTS inhibit activity of Na,K-ATPase with the same Ki values, but binding of ouabain is sensitive to ...

Na+-K+-ATPase and Na+/Ca2+exchange activities were studied in gills of Carcinus maenas in seawater (SW) and after transfer to dilute seawater (DSW). Carcinushyperregulates its hemolymph osmolarity through active uptake of Na+, Cl-, and Ca2+. In DSW total Na+-K+-ATPase activity in posterior gills quadrupled; Na+/Ca2+ exchange specific activity was unaffected, and total activity increased 1.67-fo...

Renal Na-K-ATPase activity changes adaptively in response to chronic alterations in sodium reabsorption or potassium secretion, but the role of this enzyme in rapid adjustments of renal tubular Na and K transport is not known. To evaluate this question, microsomal Na-K-ATPase specific activity and kinetics were determined in the rat and guinea pig kidney after massive but short-term (3 h) sodiu...

Cardiac steroids inhibit Na,K-ATPase and the related non-gastric H,K-ATPase, while they do not interact with gastric H,K-ATPase. Introducing an arginine, the residue present in the gastric H,K-ATPase, in the second extracellular loop at the corresponding position 334 in the human non-gastric H,K-ATPase (D334R mutation) rendered it completely resistant to 2mM ouabain. The corresponding mutation ...

Potassium secretion and sodium-potassium adenosine triphosphatase (Na-K-ATPase) activity in the distal nephron segments are known to be influenced by the dietary intake of K+. This has been attributed to a change in the plasma aldosterone level, which also influences K+ secretion and Na-K-ATPase activity in the distal nephron. To investigate whether or not dietary K+ can modulate Na-K-ATPase ac...

We have examined two distinct protein kinases, cAMP-dependent protein kinase and protein kinase C, for their ability to phosphorylate and regulate the activity of three different types of Na+,K(+)-ATPase preparation. cAMP-dependent protein kinase phosphorylated purified shark rectal gland Na+,K(+)-ATPase to a stoichiometry of approximately 1 mol of phosphate per mol of alpha subunit. Protein ki...

Lung cancer is a leading cause of global cancer deaths. Na/K-ATPase has been studied as a target for cancer treatment. Cardiotonic steroids (CS) trigger intracellular signalling upon binding to Na/K-ATPase. Normal lung and tumour cells frequently express different pump isoforms. Thus, Na/K-ATPase is a powerful target for lung cancer treatment. Drugs targeting Na/K-ATPase may induce apoptosis an...

To investigate whether nongastric H+-K+-ATPases transport Na+ in exchange for K+ and whether different beta-isoforms influence their transport properties, we compared the functional properties of the catalytic subunit of human nongastric H+-K+-ATPase, ATP1al1 (AL1), and of the Na+-K+-ATPase alpha1-subunit (alpha1) expressed in Xenopus oocytes, with different beta-subunits. Our results show that...

Cyprinus carpio is a stenohaline species but can tolerate some ranges of changes in environmental salinities, so histomorphological methods and Na+-K+ ATPase and Aquaporin 3 immunohistochemistry were performed on common carp kidney as an osmoregulatory organ in experimental groups and control in order to investigate their possible roles during salinity challenge. Five groups of fish (n=25) with...