Inhibition of angiotensin conversion and prevention of renal hypertension

Renal artery constriction in the unilaterally nephrectomized, trained dog, with maintained renal arterial hypotension, produces a prompt increase in systemic renin activity and blood pressure. The hypertension normally induced by renal artery stenosis is prevented by prior treatment with the nonapeptide Pyr-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro (SQ 20, 881), which blocks conversion of angiotensin I to angiotensin II. Constant intravenous infusion of the inhibitor over several days of renal artery constriction prevents the development of chronic renovascular hypertension. Furthermore, a single injection of the nonapeptide restores blood pressure to normal in the early phase of renovascular hypertension, but becomes progressively less effective as salt and water retention occurs in the chronic stage when plasma renin activity returns to control levels. These data provide strong evidence that the renin-angiotensin system is responsible for the initiation of renovascular hypertension in the one-kidney Goldblatt dog, but that other factors become increasingly important in chronic renovascular hypertension.