Local renin-angiotensin system in human adrenals and aldosteronomas

The local renin-angiotensin system may regulate adrenal cell growth and function. Angiotensinogen, renin, and angiotensin converting enzyme gene expression were studied in four normal adrenal glands (removed from patients with renal carcinomas) and five aldosterone-secreting adenomas. Northern blot analysis showed expression of angiotensinogen messenger RNA (mRNA) in normal adrenals at levels approximately 35 -fold lower than liver and sixfold lower than kidney. Similar angiotensinogen mRNA levels were present in two aldosteronomas, whereas a third had levels approximately 50% of those found in kidney. Renin mRNA was detectable in most normal adrenals and in three adenomas, one of which had relatively high renin mRNA levels. Angiotensin converting enzyme gene was expressed in adrenal tissue and in three adenomas. Portions from these normal adrenals and two of these aldosteronomas, as well as samples from two other adrenals and three aldosteronomas, were also studied in an in vitro supervision system coupled with active renin radioimmunometric assay, angiotensin II/HI, and aldosterone radioimmunoassay. Total amounts of active renin and angiotensin II/IH released from normal adrenals during 270 minutes of supervision were higher than the amounts released from aldosteronomas (312±35 versus 187±43 and 823±100 versus 436±55 pg/100 mg tissue, respectively; mean±SEM, p < 0.05), whereas aldosterone release from the adenomatous tissue was approximately threefold higher (320±21 versus 115±18 ng/100 mg tissue; mean±SEM, p < 0.01). Total amounts of active renin and angiotensin II/IH released by normal or adenomatous adrenal samples exceeded threefold to fourfold the amounts extracted from similar samples of the same surgical specimen. These findings provide evidence for a local renin-angiotensin system in human adrenals and in at least some aldosteronomas.© 1992 American Heart Association, Inc.