Renin in rats with spontaneous hypertension.

An age-dependent study of plasma renin activity (PRA), kidney renin activity (KRA), and plasma renin substrate was carried out in rats with spontaneous hypertension during the prehypertensive, the early hypertensive, and the established hypertensive phases of their disease. PRA and KRA were both significantly elevated before and during the initial phase of hypertension and normal or subnormal during the established phase. In normal controls, neither KRA nor PRA was significantly different during the entire growth period. Plasma renin substrate was elevated throughout the growth period in rats with hypertension. This relationship between renin and blood pressure suggests that renin may play a primary role, possibly along with other factors, in the initiation of hypertension in rats with spontaneous hypertension.