A s s T R A C X The binding of [SH]ouabain to the serosal side was studied in a chambered preparat ion of frog skin, free of connective tissue, while the short circuit (I~) was concurrent ly monitored. Both ouabain binding and 1~ inhibition proceeded as hyperbolic functions of time. A plot of the number of ouabain molecules bound vs. the corresponding values of Iae inhibition (percent) yielded ...

Madin-Darby canine kidney cells were used to study events in the postsynthetic processing and cell surface delivery of Na,K-ATPase. The photoactivable 2-nitro-5-azidobenzoyl (NAB) derivative of ouabain and an anti-ouabain antibody were employed in experiments designed to determine the time intervals required for newly synthesized Na,K-ATPase to achieve the capacity to bind ouabain and to arrive...

UNLABELLED Ouabain stimulates activation of various signaling cascades such as protein kinase B (Akt) and Extracellular-signaling-regulated kinase 1/2 (ERK 1/2) in various cell lines. Retinoic acid (RA) is commonly used to induce neuroblastoma differentiation in cultures. Upon RA administration, human neuroblastoma cell line, SK-N-SH demonstrated neurite extensions, which is an indicator of neu...

A tannin isolated from Paullinia pinnata Linn., and tannic acid, have cardiotonic actions on the isolated perfused frog heart. Paullinia tannin is more firmly "fixed" than tannic acid. Tannin solutions contain peroxide, but the cardiotonic action is not dependent on this, since drugs believed to prevent peroxide formation, and sodium pyruvate which destroys peroxides, do not prevent the cardiot...

Most of the thallium uptake by canine iliac arteries (70%) was inhibited by ouabain. The component sensitive to ouabain was significantly increased by incubating tissues in K+-free solution and reduced by low temperatures, metabolic inhibitors, and loading with lithium. The apparent Km for thallium for the ouabain-sensitive uptake was 0.47 +/- 0.046 mM. External K+ inhibited thallium uptake and...

We tested whether ouabain, an inhibitor of the sodium pump, can lead to chronic hypertension in Long-Evans rats using sensitive 24-h measurements of blood pressure. After a control week of vehicle isotonic saline infusion (14.4 ml/day), ouabain was infused intravenously at 30 pg/kg/day in intact (2K) and uninephrectomized UK) Long-Evans rats for a total of 4 weeks. Although plasma ouabain conce...

We showed before that in cardiac myocytes partial inhibition of Na+/K+-ATPase by nontoxic concentrations of ouabain causes hypertrophy and transcriptional regulations of growth-related marker genes through multiple Ca2+-dependent signal pathways many of which involve Ras and p42/44 mitogen-activated protein kinases. The aim of this work was to explore the roles of intracellular reactive oxygen ...

The distribution of Na+ pump sites (Na+-K+-ATPase) in the secretory epithelium of the avian salt gland was demonstrated by freeze-dry autoradiographic analysis of [(3)H] ouabain binding sites. Kinetic studies indicated that near saturation of tissue binding sites occurred when slices of salt glands from salt-stressed ducks were exposed to 2.2 muM ouabain (containing 5 muCi/ml [(3)H]ouabain) for...

To evaluate the effects of glucocorticoids on the Na-K pump in human subjects, were evaluated the intracellular sodium and potassium, 42K influx across and the [3H]ouabain binding to cell membranes of intact human erythrocytes from a group of subjects taking glucocorticoids and a group of normal subjects. Intracellular sodium concentration was lower (7.2 +/- 0.4 vs. 10.9 +/- 0.2 mmol/liter cell...

Endogenous cardiotonic steroids (CTS) raise blood pressure (BP) via vascular sodium calcium exchange (NCX1.3) and transient receptor-operated channels (TRPCs). Circulating CTS are superelevated in pregnancy-induced hypertension and preeclampsia. However, their significance in normal pregnancy, where BP is low, is paradoxical. Here we test the hypothesis that vascular resistance to endogenous ou...