Effect of Therapeutic and Toxic Concentrations of Ouabain Upon Potassium Content of Myocardium.

Abstract

Intracellular concentration and total amount of K in isolated, electrically stimulated guinea pig ventricle strips in the presence of therapeutic and toxic concentrations of ouabain have been investigated. Ouabain at a concentration of 0.16 [mu]g/ml produced a marked increase in force of contraction with no evidence of toxicity, but did not alter intracellular concentration or total amount of K in the heart strip either. A toxic concentration of ouabain (1 [mu]g/ml), which produced automaticity and a marked increase in resting tension followed by decline in force of contraction to zero, caused a mean decrease of 21% in intracellular K concentration. It is concluded that an alteration in the K balance of the heart is not related to the positive inotropic action of drug produced by therapeutic concentrations.