Effect of angiotensin II antagonist infusion on autoregulation of renal blood flow.

The role of the renin-angiotensin system in the autoregulation of renal blood flow was examined in the anesthetized dog. The angiotensin II antagonist, [1-sarcosine, 8-isoleucine]angiotensin II, was continuously infused into the renal artery at rates of 1 and 3 mug/min, and renin secretion rate and intrarenal distribution of blood flow as well as total renal blood flow were measured during acute reductions in renal perfusion pressure within and below the range of autoregulation. Renal autoregulation and redistribution of blood flow by pressure reduction were not disturbed by the angiotensin II antagonist. This result does not provide any evidence for a primary role of the renin-angiotensin system in renal autoregulation. Redistribution of blood flow by pressure reduction occurred independently of the renin-angiotensin system. It might depend on the differences in the resting tone among the zones.