Hormonal influence on endothelial cell angiotensin-converting enzyme activity

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Abstract
The influence of various hormones on angiotensin-converting enzyme (ACE) production and release by bovine endothelial cells in culture was studied. Dexamethasone, thyroxine (T4), and triiodothyronine (T3) stimulated ACE activity in cells and their culture supernatants without affecting cell number or protein content. The stimulating effects of dexamethasone and thyroid hormones were additive, suggesting that these hormones may have different sites of action. In addition, their stimulating effects were blocked by cycloheximide, indicating that increased enzymatic activity occurred through new protein synthesis. The exposure of cells to insulin reduced ACE activity of cells and their culture supernatants without influencing cell counts or protein content; insulin also partially inhibited the stimulation of ACE activity by dexamethasone or T3. Our studies suggest that the production of ACE by endothelial cells is under hormonal regulation. Release of ACE activity into culture supernatants parallels changes in cellular ACE activity. The results supplement previous observations made in vitro and in vivo.