Chronotropic and Inotropic Selectivity of Substituted Phenylethylamines in the Isolated Perfused Rabbit Heart

Abstract

The cardiovascular actions of a number of endogenous amines, eg. catecholamines as well as the noncatecholic phenylethylamines, were first studied systematically by Barger and Dale in 1910. Subsequently, many authors have differentiated the direct and indirect actions of these amines in vascular beds. The present study examines the effect of intracoronary artery injection of these amines on heart rate and contractility in the isolated, perfused rabbit heart, with particular attention towards establishing mechanism of action (direct and/or indirect) and detecting any selectivity for chronotropic or inotropic activity. These results could lead to a better understanding of the cardiac consequences of pathologic or iatrogenic conditions which produce increased levels of these amines. It is hoped that they will also lead to a more rational design of cardiac drugs.