In dogs anesthetized with pentobarbital, ventricular arrhythmias induced by ouabain were consistently reverted to sinus rhythm by acute lowering of the serum calcium. In ouabain-intoxicated clogs, the depressed and shortened S-T segment was elevated and lengthened by induced hypocalcemia. Potassium administered concomitantly with ouabain exerted a protective effect against ouabain intoxication....

Radioimmunoassays, Ouabain-Like Material, and Ouabain To the Editor: We read with interest the article by Bauer et al1 on the changes in the plasma concentration of a ouabain-like compound associated with vigorous exercise in both humans and dogs. The authors comment on the result that is most striking to us, namely the remarkably high concentrations of the immunoassayable substance achieved wi...

The purpose of this study was to determine whether inhibitors of prostaglandin synthesis alter the peripheral vascular effects of the cardiac glycoside, ouabain. Ouabain (35 /»g/kg) was given to 12 mongrel dogs, six of which had been pretreated 1 hour previously with the non-steroidal antiinflammatory drugs (NSAID), indomethacin or meclofenamate (6 mg/kg, iv, bolus followed by 1 mg/ min infusio...

In autosomal dominant polycystic kidney disease (ADPKD), cyst formation and enlargement require proliferation of mural renal epithelial cells and the transepithelial secretion of fluid into the cyst cavity. Na,K-ATPase is essential for solute and water transport in ADPKD cells, and ouabain blocks fluid secretion in these cells. By binding to the Na,K-ATPase, ouabain also induces proliferation i...

Ouabain is a highly polar and unusually potent sodium pump inhibitor that possesses uncommon conformational flexibility in its steroid A-ring moiety. The biological significance of ring flection in the cardiotonic steroids has not been described. Accordingly, we prepared ouabain 1,5,19- and 1,11,19-phosphates. The former stabilizes the steroid A-ring chair conformation and the latter locks the ...

Previous studies have shown that digitalis drugs, acting as specific inhibitors of cardiac Na(+)/K(+)-ATPase, not only cause positive inotropic effects, but also activate cell signaling pathways that lead to cardiac myocyte hypertrophy. A major aim of this work was to assess the role of Na(+)/Ca(2+)-exchanger, NCX1, in the above two seemingly related drug effects. Using a mouse with ventricular...

ABCC1 and ABCG2 are two transporters associated with multi-drug resistance to cancer chemotherapy. Ouabain is a cardiotonic steroid, currently considered as a hormone associated with arterial hypertension. Previous studies have suggested that ouabain can modulate ABCB1 and ABCC1 expression in cancer and renal cell lines. The present study investigated the effects of physiological concentrations...

The inhibitor g-Strophantin, also known as ouabain, is a specific inhibitor of the Na+/K+-ATPase. In this work ouabain has been used for the inhibition of the Na+/K+-ATPase in human erythrocytes and isolated enzyme from pig kidney. Enzymatic activity of the Na+/K+-ATPase has been measured in a broad concentration range of ouabain in two different in vitro investigations. As a potent inhibitor o...

With the method of in vitro incubation of the isolated rabbit cornea with the modified KEI medium, the effects of ouabain applied to the endothelial surface have been investigated. The change in corneal hydration with varying concentrations of ouabain was determined; one-half maximum rate of corneal swelling was found at an ouabain concentration of 3 x 10~ moles per liter. Endothelial permeabil...

Recent investigations demonstrate increased Na/H exchanger-1 (NHE-1) activity and plasma levels of ouabain-like factor in spontaneously hypertensive rats. At nanomolar concentrations, ouabain increases Na-K-ATPase activity, induces cell proliferation, and activates complex signaling cascades. We hypothesize that the activity of NHE-1 and Na-K-ATPase are interdependent. To test whether treatment...