Blood pressure regulation by angiotensin in the spontaneously hypertensive rats.

Plasma renin activity (PRA) was subnormal or normal in the main strain of spontaneously hypertensive rats (SHR). PRA increased greatly in the stroke-prone substrain of SHR (SHRSP) at 20-30 weeks of age. Captopril (SQ 14,225) is an orally active angiotensin-converting enzyme inhibitor. The drug acutely decreased blood pressure moderately in SHR, and markedly in SHRSP. Participation of the renin-angiotensin system in the pathogenesis of hypertension in SHR may be limited. Etiology of hypertension in connection with renal excretory function and the central and peripheral nervous system is discussed.