Action of angiotensins I, II, and III on aldosterone production by isolated rat adrenal zona glomerulosa cells. importance of metabolism and conversion of peptides in vitro.

Abstract

The steroidogenic activity of angiotensin I (AI), angiotensin II (All), and [des-Asp1]angiotension II (AIII) were assessed using dispersed rat adrenal zona glomerulosa cell incubations. Aldosterone and corticosterone outputs were measured by RIA. All at concentrations as low as 10−12 m significantly increased the output of both steroids and had a maximal effect at 10−8 m. AIII had a potency relative to All of approximately 0.3% and a threshold dose of near 10−8 m. Measurement of the survival of the peptides by both pressor bioassay and RIA revealed that AIII was degraded faster than All during incubation. The source of this peptidase activity was predominantly from the albumin in the medium. However, in medium containing albumin free from peptidase, a similar difference in the potencies of All and AIII was observed, and degradation of AIII but not All was found in the presence of glomerulosa cells. AI had a steroidogenic potency intermediate between All and AIII, with a potency relative to All of approxim...