Autoregulation of renal blood flow in rabbits immunized with angiotensin II.

Abstract

The role of renin in the autoregulation of renal blood flow was examined in rabbits actively immunized with angiotensin. Autoregulation was found to be unaffected by high serum concentrations of antiangiotensin antibody. On average, 1 ml of antiserum inactivated the pressor effect of 5.23 ± 4.95 μg of angiotensin (mean ± S.D.), range 0.64–16.0, n=17. Similar antibody concentrations were found in serum and in renal lymph, excluding major differences in antibody litres of renal interstitial fluid and serum. To evaluate the amount of antibody present in arteriolar walls, isolated hind quarters from immunized rabbits were artificially perfused. When adding angiotensin to the perfusion fluid, about 17 times higher doses were needed in immunized than in control rabbit hind quarters to give similar pressor responses. Accordingly, in the immunized rabbits antiangiotensin antibody was present both in arteriolar walls and in renal interstitial fluid, thus providing strong evidence that angiotensin is not essential in the autoregulation of renal blood flow.