Ouabain inhibited 86RbCl uptake by 80% in rabbit gastric superficial epithelial cells (SEC), revealing the presence of a functional Na+,K+-ATPase [(Na+ + K+)-transporting ATPase] pump. Intact SEC were used to study the ouabain-sensitive Na+,K+-ATPase and K+-pNPPase (K+-stimulated p-nitrophenyl phosphatase) activities before and after lysis. Intact SEC showed no Na+,K+-ATPase and insignificant M...

Apart from Na(+),K(+)-ATPase, a second sodium pump, Na(+)-stimulated, K(+)-independent ATPase (Na(+)-ATPase) is expressed in proximal convoluted tubule of the mammalian kidney. The aim of this study was to develop a method of Na(+)-ATPase assay based on the method previously used by us to measure Na(+),K(+)-ATPase activity. The ATPase activity was assayed as the amount of inorganic phosphate li...

We present evidence that Na-K-ATPase in the rat proximal tubule is directly activated by ANG II much faster than previously observed. Specifically, we show that a 2-min exposure to 0.1 and 1 nM ANG II slowed the rate of intracellular sodium accumulation in response to an increase in extracellular sodium added in the presence of gramicidin D. From these data, we show that ANG II directly stimula...

background: the presence of rennin-angiotensin components in mammalian ovaries and their involvement in ovarian physiology have been established. in the present study, effects of angiotensin ii (ang ii) on sodium-potassium adenosine triphosphatase (na+/k+/atpase) expression and development of sheep embryos was evaluated. methods: the abattoir-derived cumulus oocyte complexes (coc) were randomly...

Changes in Na(+)/K(+)-ATPase activity and abundance associated with environmental salinity were investigated in the gills and rectal gland of the Atlantic stingray Dasyatis sabina. Using a ouabain-specific ATPase assay and western blotting, we found that stingrays from fresh water had the highest activity and highest relative abundance of Na(+)/K(+)-ATPase in the gills. Using immunohistochemist...

Alveolar epithelial cells effect edema clearance by transporting Na(+) and liquid out of the air spaces. Active Na(+) transport by the basolaterally located Na(+)-K(+)-ATPase is an important contributor to lung edema clearance. Because alveoli undergo cyclic stretch in vivo, we investigated the role of cyclic stretch in the regulation of Na(+)-K(+)-ATPase activity in alveolar epithelial cells. ...

Renal sodium homeostasis is a major determinant of BP and is regulated by several natriuretic and antinatriuretic hormones. These hormones, acting through intracellular secondary messengers, either activate or inhibit proximal tubule Na,K-ATPase. It was shown previously that phorbol esters and angiotensin II and serotonin induce the phosphorylation of both Ser-11 and Ser-18 of the Na,K-ATPase a...

The present study investigated whether maximal in vitro Na-K-ATPase activity in human skeletal muscle is changed with exercise and whether it was altered by acute hypoxia. Needle biopsies from 14 subjects were obtained from vastus lateralis before and after 4 min of intense muscle activity. In addition, six subjects exercised also in hypoxia (12.5% oxygen). The Na-K-ATPase assay revealed a 19% ...

Mutations in the RS1 gene cause X-linked juvenile retinoschisis (XLRS), a hereditary retinal dystrophy. We recently showed that retinoschisin, the protein encoded by RS1, regulates ERK signaling and apoptosis in retinal cells. In this study, we explored an influence of retinoschisin on the functionality of the Na/K-ATPase, its interaction partner at retinal plasma membranes. We show that retino...