Hormone replacement therapy increases plasma level of angiotensin II in postmenopausal hypertensive women

The renin-angiotensin-aldosterone system plays a major role in the pathogen esis of hypertension by enhancing the production or the activity of angiote nsin II (ANG II). We evaluated the effects of hormone replacement therapy ( HRT) on the renin-angiotensin-aldosterone system and on bradykinin in postm enopausal women (PMW) who were hypertensive or normotensive. Subjects inclu ded 28 PMW whose elevated blood pressure (BP) was well controlled on antihy pertensive agents excluding diuretics, angiotensin-converting enzyme (ACE) inhibitors, and ANC II receptor antagonists. As controls, we evaluated 16 n ormotensive PMW. All subjects received oral HRT daily for 6 months. The pla sma levels of angiotensin I (ANG I), ANG II, and bradykinin as well as plas ma renin activity (PRA) showed a significant increase in HRT in the hyperte nsive group, but not in the normotensive group. The serum ACE activity show ed a significant decrease in both groups, but the plasma level of aldostero ne was unchanged. Despite the decrease in serum ACE activity, there was an increase in the plasma ANG II level. Hormone replacement therapy increased the level of ANG II in the hypertensive women, but their BP was unaffected. The increase in plasma bradykinin level may maintain homeostasis in the pr esence of an increase in plasma ANG II, which is a risk factor for cardiova scular disease. Hormone replacement therapy was associated with a decrease in serum ACE and an increase in plasma bradykinin in hypertensive PMW. Acco rdingly, the protective effect of HRT against cardiovascular disease in PMW can be provided by a decrease in ACE activity and an increase in bradykini n. (C) 2001 American Journal of Hypertension, Ltd.