Abstract

Dopamine dilates the renal vascular bed by a nonadrenergic mechanism but does not cause similar dilation in the femoral vascular bed (McNay et al., 1965) . The chemical structure required for such renal vasodilation was investigated by injecting 44 phenylethylamines and apomorphine into the renal artery of anesthetized dogs. Renal blood flow was measured by an electromagnetic flowmeter. A compound was considered to exert dopamine-like activity if it dilated the renal vascular bed after administration of phenoxybenzamine and propranolol, but did not dilate the femoral vascular bed under similar conditions. Only the N-methyl analog of dopamune, Epinune, possessed unequivical dopamine-like activity. Amines with other substitutions on either the benzene ring or the side chain of the dopamine molecule did not exhibit such activity. Apomorphine appeared to produce renal vasodilating actions similar to, but less potent than, those of dopamine. These studies indicate that the molecular structural requirements for dopamine-like renal vasodilation are more specific than those for the alpha and beta adrenergic effects of sympathomimetic amines.