Cardiotonic activity of certain steroids and bile salts.

Abstract

The effects of 23 plant and animal steroids, steroid hormones, and bile acids, and nine of their salts or soluble conjugates, have been investigated in isolated frog hearts. All but five of the compounds produced significant augmentation of frog hearts made hypodynamic by prolonged perfusion. The augmentation was not usually accompanied by changes in heart rate, and no steroid caused systolic arrest. Eight water-soluble steroid salts were perfused through isolated rabbit hearts when they had become hypodynamic by prolonged perfusion. In each case the coronary flow increased significantly whether the heart rate and force of contraction increased or not. Thus, when cardiotonic activity was observed, it appeared to be a direct effect and not secondary to the increased coronary flow. It would seem that the lactone ring of the cardiac glycoside molecule is responsible for the development of systolic arrest, and that the cardiotonic action is, at least partly, a function of the cyclopentenophenanthrene nucleus.