In vitro evidence for dopaminergic receptors in human renal artery

Effects of dopamine on human renal arteries were pharmacologically investigated in vitro. Norepinephrine (5 X 10(-10)-5 X 10(-5) M) produced concentration-dependent contractions of isolated renal arterial strips, which were significantly depressed by prior administration of phentolamine or phenoxybenzamine. Isoproterenol (4 X 10(-10)-4 X 10(-6) M) concentration dependently relaxed the strips under potassium contracture, but a high dose (4 X 10(-5) M) constricted them. Biphasic responses to isoproterenol were changed to concentration-dependent contractions by prior administration of propranolol, and abolished by propranolol together with phentolamine. Dopamine (5 X 10(-8)-5 X 10(-4) M) produced concentration-dependent contractions of human renal arteries, which were not significantly influenced by propranolol but which were reversed to relaxations by phentolamine. Dopamine-induced relaxations, which were obtained after administration of phentolamine, were not significantly affected by propranolol, but were significantly depressed by combined application of propranolol and haloperidol, or of propranolol and droperidol. Results suggest that isolated human renal arteries have dopaminergic receptors in their smooth muscles which show relaxations of renal arteries after alpha-adrenoceptor blockade.