Effect of long-term hormone replacement therapy on angiotensin-converting enzyme activity and bradykinin in postmenopausal women with essential hypertension and normotensive postmenopausal women

Objective: Hormone replacement therapy (HRT) reduces the incidence of cardi ovascular disease in postmenopausal women. Three-month short-term HRT in po stmenopausal women with essential hypertension increased the plasma concent rations of bradykinin with decreased serum angiotensin-converting enzyme (A CE) activity, which may be partially responsible for the cardioprotective e ffects of HRT. The objective was to determine whether 12-month long-term HR T in postmenopausal women with essential hypertension would maintain the de creased ACE activity and increased bradykinin levels and whether long-term HRT would increase the plasma bradykinin concentrations of normotensive pos tmenopausal women who had shown no significant changes in the 3-month HRT s tudy, despite their decreased serum ACE activity. Design: Twenty hypertensive and 15 normotensive postmenopausal women were t reated with conjugated estrogens (0.625 mg/day) and medroxyprogesterone (2. 5 mg/day) for 12 months. Twenty hypertensive and 15 normotensive postmenopa usal women were used as controls. The controls were not treated with HRT. S erum ACE activity and plasma bradykinin concentrations were measured at bas eline and at 12 months. Results: Long-term HRT in both hypertensive and normotensive postmenopausal women significantly decreased serum ACE activity from 15.5 +/- 0.7 IU/L an d 16.0 +/- 0.9 IU/L, respectively, at baseline to 13.3 +/- 0.5 IU/L and 14. 2 +/- 0.9 IU/L, respectively, 12 months after the start of HRT (p < 0.05 an d p < 0.05, respectively). Long-term HRT in both hypertensive and normotens ive postmenopausal women also significantly increased plasma bradykinin con centrations from 22.1 +/- 4.4 pg/mL and 19.2 +/- 3.0 pg/mL, respectively, a t baseline to 86.7 +/- 21.2 pg/mL and 73.5 +/- 23.0 pg/mL, respectively, 12 months after the start of HRT (p < 0.01 and p < 0.05, respectively). No si gnificant changes in serum ACE activity or plasma bradykinin concentrations were observed in the control groups. Conclusions: Long-term HRT in hypertensive and normotensive postmenopausal women decreases their serum ACE activity and increases their plasma bradyki nin concentrations. Thus, maintenance of elevated bradykinin with decreased serum ACE activity by HRT may be useful in reducing the risk of cardiovasc ular disease in both hypertensive and normotensive postmenopausal women.