Effects of Catecholamines and Renal Nerve Stimulation on Renln Release in the Nonfilterlng Kidney

The mechanisms whereby catecholamines and renal nerve stimulation increase renin secretion were studied in dogs with nonfiltering kidneys. In six dogs, epinephrine was infused into the renal artery at a rate that decreased renal blood flow to half of the control value. Papaverine was then infused into the renal artery to block the decrease in renal blood flow produced by the catecholainine, and the epinephrine infusion was resumed while the papaverine infusion was continued. In this experiment, renin release increased during infusion of epinephrine alone, but no change occurred with epinephrine during papaverine infusion. The protocol for the experiment on six other dogs was similar except that the infused catecholamine was norepinephrine. In this experiment, norepinephrine increased renin release both prior to and during papaverine infusion. In seven dogs, the effect of electrical stimulation of the renal nerves on renin secretion was studied both before and during the infusion of papaverine into the renal artery; renin release increased strikingly both before and during papaverine infusion. It is suggested that epinephrine increased renin secretion in the nonfiltering kidney by an action on the renal arterioles. In contrast, norepinephrine and renal nerve stimulation apparently increased renin secretion in the nonfiltering kidney by a direct effect on the juxtaglomerular cells. These data provide evidence for specific mechanisms of action of epinephrine, norepinephrine, and the renal nerves in renin release.