Effects of angiotensin II on steroid metabolism and hepatic blood flow in man

Abstract

Metabolic clearance rates (MCR) of aldosterone, cortisol, 11-deoxycorticosterone (DOC), corticosterone, and progesterone were simultaneously measured by constant infusion in eight control subjects before and during angiotensin II infusion in subpressor (3 ng/min per kg) and pressor (22 ng/min per kg) doses. Plasma levels of aldosterone and cortisol, the heat-labile protein-bound fraction of aldosterone, and hepatic blood flow (HBF) (as estimated by the fractional clearance of indocyanine green) were determined concomitantly. Angiotensin II in a subpressor dose produced a significant decrease of the MCR of aldosterone (by 23%), cortisol (by 16%), DOC (by 26%), corticosterone (by 14%) and progesterone (by 33%). The pressor dose further decreased the respective MCR by 37%, 21%, 40%, 28%, and 42% of the baseline value. Plasma aldosterone levels rose by 317% with subpressor and by 434% with pressor doses. HBF decreased by 18% with subpressor and by 33% with pressor doses of angiotensin II. Furthermore, there were significant negative correlations between the MCR of each steroid and the respective values of the fractional clearance of indocyanine green. We conclude that angiotensin II, by its vasoconstrictive action on the splanchnic vascular bed, decreases the MCR of aldosterone, cortisol, DOC, corticosterone, and progesterone. This decrease has to be taken into account when considering the stimulatory effect of angiotensin II on various plasma steroid concentrations.