1. The uptake of (3)H-digitoxin, (3)H-ouabain and (3)H-dihydro-ouabain by isolated guinea-pig atria has been studied and compared with the inhibition of the sodium pump and with the inotropic effect.2. Analysis of the curve relating the uptake of digitoxin and ouabain at equilibrium to the bath concentration enabled a non-saturable and a saturable binding site to be distinguished.3. The uptake of inactive doses of dihydro-ouabain was only by a non-saturable mechanism.4. The uptake of labelled digitoxin and ouabain was reduced in the presence of another glycoside. The amount of bound glycoside was nearly equivalent to the estimated non-saturable uptake.5. The uptake was reduced at 4 degrees C to the clearance of the non-saturable site.6. ED50 of digitoxin and of ouabain for inhibition of the sodium pump were measured and compared to the ED50 for inotropic effect and to the concentrations producing a half-saturation of the saturable binding site.7. It is concluded that binding to the saturable site may be responsible for the cardiac actions of the glycosides.
Tritiated digoxin binding to (Na+ + K+)-activated adenosine triphosphatase: possible allosteric site
The uptake of cardiac glycosides by intestinal smooth muscle of the guinea-pig in relation to digitalis receptors
A comparison of the accumulation and release of 3H-ouabain and 3H-digitoxin by guinea-pig heart muscle
ON THE IDENTITY OF THE ION-PUMPING-ATPASE IN THE CELL MEMBRANE OF THE MYOCARDIUM WITH A DIGITALIS RECEPTOR ENZYME
Bilary and urinary excretion of five cardiac glycosides and its correlation with their physical and chemical properties
Acute myocardial uptake of digoxin in humans: correlation with hemodynamic and electrocardiographic effects.
Independence of the positive inotropic effect of ouabain from the inhibition of the heart Na+/K+ pump
Studies on the kinetics of (3H)-ouabain uptake and exchange in the isolated papillary muscle of the guinea-pig
Stimulation and inhibition of the sodium pump by cardioactive steroids in relation to their binding sites and their inotropic effect on guinea-pig isolated atria
Time course of ouabain uptake in isolated myocardial cells: dependence on extracellular potassium and calcium concentration
Electrophysiological studies of some semisynthetic cardiac glycoside derivatives in isolated papillary muscle of the guinea-pig
Proceedings: Prostaglandin D1 inhibits the increase in vascular permeability in rat skin produced by prostaglandin E1, E2 and D2
Beta-methyl-digoxin. V. Protein binding, tissue distribution and extra-cardiac effects in rats and mice
Subcellular distribution of Deslanatoside C-3H in isolated guinea pig hearts. Interaction of other drugs
Influence of highly unsaturated phosphatidylcholine on the effects of ouabain and some cardioactive drugs on cardiac contractile force and Na+, K+-ATPase activity
Effects of vanadate in cultured rat heart muscle cells. Vanadate transport, intracellular binding and vanadate-induced changes in beating and in active cation flux
Cardiac glycosides are a diverse family of naturally derived compounds that bind to and inhibit na+/k+-atpase. Discover the latest research on cardiac glycosides heres.