Control of adrenal cell proliferation by AT(1) receptors in response to angiotensin II and low-sodium diet

The effects of angiotensin II (ANG II), the angiotensin type I (AT(1)) rece ptor antagonist losartan, and low-sodium diet on rat adrenal cell prolifera tion were studied in vivo with immunocytochemistry. Both ANG II and low-sod ium diet increased proliferation of endothelial cells of the zona glomerulo sa. Losartan prevented ANG II-induced hyperplasia of glomerulosa cells but not the effects of a low-sodium diet. Glomerulosa cells after ANG If + losa rtan treatment appeared hypertrophied compared with those of controls. Prol iferative effects of ANG II and low-sodium diet in the reticularis were blo cked by losartan. No changes were seen in the fasciculata. Proliferation in the medulla was increased with losartan, was decreased by ANG II, but was unaffected by low-sodium diet. In conclusion, I) cell hypertrophy and proli feration of glomerulosa cells are mediated by AT(1) receptor-dependent and -independent processes, 2) proliferation of reticularis cells is controlled by AT(1) receptors, and 3) reciprocal control of chromaffin cell prolifera tion by ANG II may involve indirect ATL-dependent processes.