[Inhibition by propranolol of the ouabain binding to myocardium].

The amount of ouabain bound to an enriched fraction of heart or kidney medulla is reduced by propranolol. The inhibitory effect is greater under conditions in which complex II formation is promoted. Similar concentrations of propranolol are able to produce a reduction in Na+, K+-ATPase activity, by reduction of the number of active sites without changes in ionic affinity. The lack of stereospecificity and the high concentrations (greater than 10(-4)M) required indicate that this effect is independent of beta adrenergic blockade. Effectiveness reduction of cardiac glycosides in the presence of propranolol could be due to inhibition of drug interaction with its receptor.