Control of adrenal cell proliferation by AT1 receptors in response to angiotensin II and low-sodium diet.

The effects of angiotensin II (ANG II), the angiotensin type 1 (AT1) receptor antagonist losartan, and low-sodium diet on rat adrenal cell proliferation were studied in vivo with immunocytochemistry. Both ANG II and low-sodium diet increased proliferation of endothelial cells of the zona glomerulosa. Losartan prevented ANG II-induced hyperplasia of glomerulosa cells but not the effects of a low-sodium diet. Glomerulosa cells after ANG II + losartan treatment appeared hypertrophied compared with those of controls. Proliferative effects of ANG II and low-sodium diet in the reticularis were blocked 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, 1) cell hypertrophy and proliferation of glomerulosa cells are mediated by AT1 receptor-dependent and -independent processes, 2) proliferation of reticularis cells is controlled by AT1 receptors, and 3) reciprocal control of chromaffin cell proliferation by ANG II may involve indirect AT1-dependent processes.