Effect of intrarenal administration of dopamine on renin release in conscious dogs.

We investigated the effect of intrarenal administration of dopamine on renin release in conscious dogs. Dopamine in doses ranging from 0.28 to 3.0 micrograms . kg(-1) . min(-1) produced a significant increase in systemic plasma renin activity (PRA) and renin secretion rate without altering systemic blood pressure. Dopamine also induced renal vasodilatation and natriuresis within this dose range. To determine if the dopamine-induced renin release is related to its vasodilatory action, two other vasodilators, papaverine and acetylcholine, were infused into the renal artery, but neither, in doses that produced a rise in renal blood flow similar to that of dopamine, had any effect on PRA. As dopamine can activate alpha- and beta-adrenergic receptors in addition to dopaminergic receptors, experiments were also performed to characterize the type of receptors involved in dopamine-induced renin release. Intrarenal infusion of sulpiride and haloperidol, dopamine antagonists, significantly inhibited dopamine-induced renin release and renal vasodilatation. In contrast, intrarenal infusion of propranolol failed to alter dopamine-induced rise in PRA or renal blood flow. Simultaneous infusion of phentolamine and dopamine, on the other hand, produced a significant potentiation of dopamine-induced renin release and renal vasodilatation. In conclusion, our studies demonstrate that dopamine is capable of inducing renin release and renal vasodilatation in conscious dogs. Moreover, such actions of dopamine are mediated through activation of specific dopamine receptors in the kidney. Finally, we present evidence for the existence of the intrarenal alpha-adrenergic mechanism that is inhibitory to renin release.