Role of vascular angiotensin converting enzyme in hypertension

The possible role of vascular angiotensin converting enzyme (ACE) in the maintenance of one-kidney, one clip (1-K,1C) hypertensive rats was studied in comparison with age-matched, one-kidney (1-K) normotensive rats. Mean blood pressure was elevated after partial occlusion of the left renal artery with unilateral nephrectomy, and the high blood pressure persisted for at least 11 weeks, whereas no significant changes in mean blood pressure were observed in 1-K rats. Plasma and vascular renin activities and plasma ACE activity did not differ between the two groups of rats, both 5 and 11 weeks after operation. In contrast, ACE activity in lung and mesenteric arteries in 1-K,1C hypertensive rats was significantly elevated 11 weeks after operation, but not 5 weeks after operation, compared with the matched 1-K normotensive rats. In addition, the decreases in mean blood pressure induced by ACE inhibition were significantly greater in 1-K,1C rats than those in 1-K rats. These results indicate that the elevation of vascular ACE activity may play an important role in the maintenance of high blood pressure and may result in hypotension in response to ACE inhibitors in the chronic stage of 1-K,1C hypertension.