Different mechanisms maintaining high blood pressure in chronic one-kidney, one-clip, and two-kidney, one-clip hypertensive rats.

To evaluate the difference of the blood pressure regulating mechanisms of chronic (12-14 weeks) one-kidney, one-clip (1K-1C) and chronic two-kidney, one-clip (2K-1C) hypertensive rats, we administered captopril, captopril plus indomethacin, and indomethacin to the rats. Pretreatment values of plasma renin concentration, plasma aldosterone concentration and urinary kallikrein excretion were significantly higher in 2K-1C than in 1K-1C hypertensive rats. Captopril-induced blood pressure reduction was greater in 2K-1C than in 1K-1C hypertensive rats. When captopril was administered to the rats treated with indomethacin, captopril-induced blood pressure reduction was attenuated only in 2K-1C hypertensive rats. Indomethacin produced renal impairment and further raised the blood pressure in 1K-1C hypertensive rats, but did not in 2K-1C hypertensive rats. These results suggest that the renin-angiotensin system functions to maintain high blood pressure more predominantly in chronic 2K-1C than in 1K-1C hypertensive rats. The renal kallikrein-kinin system is suppressed in chronic 1K-1C hypertensive rats but not in 2K-1C hypertensive rats. The renal prostaglandin system is more important for regulating the renal circulation in chronic 1K-1C than in 2K-1C hypertensive rats.