Studies on digitalis. 13. A comparison of the effects of potassium on the inotropic and arrhythmia-producing actions of ouabain.

Although it is generally recognized that digitalis-induced arrhythmias can be suppressed by the administration of potassium (1-3), it is not clear whether the potassium ion also influences the positive inotropic effect exerted by the glycosides on the intact mammalian heart. Clarification of this problem is important in the understanding of the interrelationships between the actions of glycosides and potassium, and is clinically significant in view of the frequency with which potassium is administered to patients who are or have been receiving digitalis. Accordingly, the present investigation was undertaken to determine the manner in which potassium suppression of ouabaininduced arrhythmias affects the augmentation of ventricular contractile force produced by the administration of the glycoside.