EFFECT OF CONJUGATED ESTROGEN ON PERIPHERAL FLOW-MEDIATED VASODILATION IN POSTMENOPAUSAL WOMEN

Estrogen replacement protects against cardiovascular morbidity and mor tality in postmenopausal women. Conjugated estrogen is the main hormon e used in these studies, However, the vascular effects of this type of estrogen are, to a large extent, unexplored. The objective of this st udy was to evaluate short-term endothelium-dependent vascular effects of intravenously conjugated estrogen at 2 dose levels. Eleven postmeno pausal women were included. Each study subject was given 2.5 and 5 mg of conjugated estrogen or placebo in random order with at least 1 week between each investigation in a double-blind study design, The vascul ar reactivity of the brachial artery was studied using the duplex tech nique before and 30 minutes after the intravenous administration of st udy drug, Reactive hyperemia was used to study the flow-mediated vasod ilation. Serum estradiol increased significantly and dose dependently 5 minutes after conjugated estrogen infusion. The flow-mediated vasodi lation at baseline before drug administration was 1.8 +/- 2.0% (mean /- SD) after an average 400% increase in local blood flow. Conjugated estrogen at a dose of 2.5 mg caused an increase in flow-mediated vasod ilation from 1.8 +/- 2.1% at baseline to 5.4 +/- 2.8% after infusion ( p < 0.05 vs placebo), whereas 5 mg caused an increase from 1.9 +/- 1.5 % at baseline to 7.0 +/- 3.3% after infusion (p < 0.05 vs placebo). In travenous injection of conjugated estrogen significantly improves the peripheral vascular reactivity in postmenopausal women. (C) 1998 by Ex cerpta Medico, Inc.