Acute effects of captopril on blood pressure and regional blood flows in two types of renovascular hypertensive rats in conscious state.

Mean arterial pressure and three regional blood flows--renal, superior mesenteric, and hindquarter flows--were monitored in conscious normotensive control rats (NCR), in two-kidney, one-clip (two-kidney), and in one-kidney, one-clip (one-kidney) hypertensive rats. After administering captopril, an angiotensin-converting enzyme inhibitor, mean arterial pressure decreased in all three groups. However, lowering of arterial pressure was not statistically significant in any of the groups. Renal flow increased significantly in the intact artery of two-kidney hypertensive rats, whereas it did not significantly increase in the clipped artery of one-kidney hypertensive rats and in the intact artery of NCR. Superior mesenteric flow increased significantly only in one-kidney hypertensive rats. Hindquarter flow did not significantly change in the three groups. Regional resistance reduced significantly in not only renal but also in superior mesenteric vascular area in two-kidney hypertensive rats, whereas it did not reduce significantly in these two vascular areas in one-kidney hypertensive rats and in NCR. The present findings show that the renin-angiotensin-mediated vasoconstriction plays a role in not only renal but also in superior mesenteric vascular area in two-kidney hypertensive rats, whereas it hardly plays a role in these three vascular beds in one-kidney hypertensive rats.