Role of angiotensin II in experimental renal hypertension in the rabbit

Hypertension was produced in rabbits by constricting the left renal artery; in nine rabbits the opposite kidney was removed and in eight rabbits the opposite kidney was left intact. To investigate the role of angiotensin II (A-II), 1-sarcosine-8-alanine angiotensin II, a competitive antagonist of A-II, was infused at 6 mug/min per kg body wt for 30 min. In a control group of seven unilaterally nephrectomized rabbits mean arterial pressure averaged 81 mmHg and infusion of the A-II antagonist did not alter the arterial pressure. In a group of Na-depleted rabbits, arterial pressure decreased from 81 to 63 mmHg (P less than 0.01) in response to the A-II analogue. Thirty days after renal artery constriction, seven of the nine one-kidney hypertensive rabbits had normal values for plasma renin activity (PRA) and during infusion of the A-II antagonist arterial pressure was unchanged. However, two rabbits had elevated PRA and the arterial pressure decreased during infusion of the angiotension analogue. In the two-kidney hypertensive rabbits, PRA was normal and arterial pressure was unchanged by infusion of the A-II antagonist. These studies provide evidence that hypertension developed with either a high or normal A-II plasma level in the one-kidney animals; the two-kidney rabbits developed chronic hypertension in which no role for A-II could be demonstrated.