Effect of [Sar1, Ala8]angiotensin II on renal vascular resistance

Partial occlusion of the renal artery (RAO) was induced in dogs anesthetized with pentobarbital or morphine chloralose-urethan. The effect of [Sar1, Ala8]angiotensin II (P-113) was compared before and during RAO on blood flow and vascular resistance of the contralateral kidney. An increase in renin secretion rate was obtained in the ischemic kidney, which was accompanied by an increase in renal vascular resistance (RVR) in the contralateral kidney and a rise in systemic blood pressure. P-113 given intra-arterially to the contralateral kidney consistently increased renal blood flow and decreased RVR during RAO, but did not alter RVR significantly before RAO. The elevation in renin secretion rate decreased between 30 and 122 min after the initiation of RAO in the pentobarbital-anesthetized dogs but not in the chloralose-urethan-anesthetized dogs. These experiments indicate that during RAO release of renin causes, through formation of angiotensin, an increase in RVR in the contralateral kidney and intra-arterial administration of P-113 restores the vascular resistance to a near-normal level.