Ethinyl estradiol acutely attenuates abnormal coronary vasomotor responses to acetylcholine in postmenopausal women

women is associated with a 50 % reduction in the clinical mani-festations of coronary artery disease. The mechanisms are not known, although one potential explanation is estrogen-induced modulation of coronary vasoreactivity. Acetylcholine is an endo-thelium-dependent vasodilator that may be used to assess coro-nary vasoreactivity and elicits coronary responses that parallel those found with common daily vasomotor stimuli. Therefore, we tested whether estrogen attenuates abnormal coronary vasomo-tor responses to acetylcholine in postmenopausal women. Methods and Results Acetylcholine-induced changes in cor-onary flow, resistance, and cross-sectional area were deter-mined before and 15 minutes after intravenous administration of ethinyl estradiol (EE, 35,ug) in 15 postmenopausal women. The influence of estrogen on basal coronary flow, resistance, and epicardial cross-sectional area was also assessed by mea