A Comparison of the Cardiac Stimulating and Bronchodilator Actions of Selected Sympathomimetic Amines

Abstract

Summary Cardiac stimulating actions of selected sympathomimetic amines have been compared. In the case of the β-phenethanola-mines described here, this effect was increased by substitution of a cyclopentyl or isopropyl group in the N-center. Alkyl (methyl, ethyl or propyl) substitution of the a-carbon of the side chain markedly reduced cardiac stimulation and in the case of the N-substituted catecholamines described here, disclosed differences in potency for effects on force as compared to rate. The structural requirements for initiating sympathomimetic cardio-acceleration and for increases in the force of contraction differ from those which are optimal for bronchodilator action. The receptors responding to sympathomimetic amines may consist of a population differing in sensitivity to structural variation of the agonist (and possibly also to the various antagonists).