Conditions for enhancement of renin release by isoproterenol, dopamine, and glucagon

Isoproterenol infusion increases renin release at low but not at control blood pressure. To examine whether this effect is dependent on arteriolar dilation and is specific for agonists of beta-adrenoceptors, responses to intrarenal infusion of isoproterenol (0.2 micrograms.kg body wt-1.min-1), glucagon (0.1 micrograms.kg body wt-1.min-1), and dopamine (1 micrograms.kg body wt-1.min-1) were compared at control and low or high ureteral pressure, which also dilates the renal arterioles. During renal arterial constriction, renin release was equal at two perfusion pressures below the range of autoregulation and was 76 +/- 24 micrograms/min higher during isoproterenol than during propranolol administration. Intravenous infusion of isoproterenol gave qualitatively similar results. Intrarenal infusion of glucagon and dopamine increased renin release by 13 +/- 3 and 22 +/- 12 micrograms/min, respectively; enhancement of renin release was also present after propranolol administration. During ureteral occlusion, intrarenal infusion of isoproterenol, dopamine, and glucagon increased renin release from 30-40 micrograms/min by 78 +/- 11, 13 +/- 3, and 31 +/- 10 micrograms/min, respectively. At control blood and ureteral pressure, the effects on renin release of infusing isoproterenol, dopamine, or glucagon were small or absent. Thus, isoproterenol, dopamine, amd glucagon enhance renin release when the arterioles are dilated by renal arterial constriction or ureteral occlusion.