Intrarenal formation of angiotensin I.

In 5 patients and 16 dogs the mean concentration of angiotensin I, but not II, was higher in the plasma of the renal vein than in the plasma of the renal artery. The fact that I was higher in the vein than in the artery supports the concept that I is formed in the renal vasculature. In the vein the mean concentration of I was 45 times higher than that of II. The probable formation of angiotensin I within the kidney and its high concentration in the renal vein suggest that if the renin angiotensin system plays a role in the regulation of intrarenal blood flow, then angiotensin I may be the major effector hormone in this process.