The Metabolism of Angiotensin II

Abstract

1. I 131 -labeled angiotensin II has been employed to study the metabolism of this polypeptide. 2. Following the intravenous administration of angiotensin II-I 131 to normotensive and untreated primary benign hypertensive subjects, a slower angiotensin II degradation rate and a larger final volume of distribution of angiotensin II-I 131 was found in the hypertensive than in the normotensive patients. The slow rate of degradation of angiotensin II may be responsible for the increased quantity and concentration of this polypeptide in the body fluids. 3. Greater quantities of angiotensin II-I 131 are degraded in vitro by sera from untreated primary benign hypertensive patients than from normotensive or secondary renal hypertensive patients. There is evidence for the presence of a serum factor or factors enhancing angiotensin II-I 131 degradation and for the presence of a heat labile inhibitor.