Renin-angiotensin system in spontaneously hypertensive rats.

Plasma and kidney renin activities (PRA, KRA) were determined in male spontaneously hypertensive rats (SHR), the inbred strain of F27-30. Blood samples of 0.5 ml for PRA determination were obtained through a cannula inserted into the abdominal aorta without anesthesia to minimize renin release from the kidney. The PRA was 30 wk. The KRA of SHR at age 10, 20, and 30 wk was also lower, confirming a previous report. At 5 wk of age, KRA was slightly higher than that of normal controls. At 50 wk of age, PRA and KRA were significantly lower in SHR (F25) from a random-bred colony than in normal Donryu rats. It is suggested that the renin-angiotensin system is suppressed in SHR as a compensatory reaction against blood pressure elevation.