Effects of angiotensin II on blood pressure, plasma renin activity, and aldosterone in the fetal lamb.

11 chronically catheterized fetal lamb preparations between 102 and 138 days of gestation (term 140--150 days) were studied after a continuous infusion of exogenous angiotensin II (0.25 microgram/kg/min). The pressor response to angiotensin II was delta 12.4 +/- 1.1 mm Hg. Plasma renin activity decreased from 6.33 +/- 2.49 ng/ml/h (mean and SEM) to 3.08 +/- 1.21 (p less than 0.05) after 30 min of the angiotensin II infusion. Plasma aldosterone showed a small increase from 5.13 +/- 0.9 to 7.34 +/- 1.22 ng/dl after 60 min (p less than 0.05) of the angiotensin II infusion. These results indicate that a pressor dose of angiotensin II will inhibit plasma renin activity and stimulate aldosterone secretion during the last trimester in the fetal sheep.