Metabolism of Angiotensin II-I 131 in Normotensive and Hypertensive Human Subjects

Abstract

Angiotensin II-I131 was administered intravenously to 5 normotensive, 2 benign essential hypertensive and one malignant essential hypertensive subjects. The plasma radioactivity after injection was studied by electrophoretic and chemical analyses. Approximately 1/3 of the total blood radioactivity was in the erythrocytes and the remaining 2/3 was in the plasma. The rate of disappearance of plasma radioactivity after angiotensin II-I131 administration was more rapid in the 5 normotensive control patients than in 3 subjects with essential hypertension. The 5 normotensive subjects had smaller apparent spaces of distribution and more rapid degradation rates of angiotensin II than the 3 subjects with essential hypertension. The mean values for the apparent volumes of distribution of angiotensin II were approximately 23 liters in the normotensive subjects and 29 liters in the subjects with benign and malignant hypertension. The total amounts of angiotensin II which are present in the body and which are readily exchangeable with the blood angiotensin II may be calculated to approximately average 0.41 ug in the normotensive subjects, 1.10 ug in the subjects with benign essential hypertension and 9.3 ug in the malignant hypertensive subject.