Control of cell proliferation in the rat adrenal gland in vivo by the renin-angiotensin system

Abstract

Adrenal cytogenesis was investigated in response to 1) subcutaneous infusions of angiotensin (ANG) II (200 ng.kg-1.min-1); 2) high and low sodium intake; and 3) captopril treatment (10 mg.kg-1.day-1). Cell proliferation was assessed as uptake of 5-bromo-2'-deoxyuridine (BrdUrd) into nuclei. BrdUrd, infused continuously throughout 2 wk of treatment, was detected immunocytochemically. ANG II and sodium restriction caused hypertrophy of the zona glomerulosa with two- to threefold increases in BrdUrd indexes. After captopril, the glomerulosa appeared atrophied with pyknotic nuclei, but the BrdUrd index was unchanged. Zonae intermedia and fasciculata were unaffected by any treatment. Zona reticularis epithelial cells proliferated in response to ANG II and sodium restriction but were unaffected by captopril. In the medulla, captopril increased BrdUrd uptake, whereas ANG II, but not low sodium, caused a decrease. In conclusion, 1) proliferation of the glomerulosa and reticularis cells is specifically controlled by ANG II, 2) captopril may cause glomerulosa cells to die, and 3) blood pressure may control proliferation of the medulla.