Effect of 6-wk estrogen withdrawal or replacement on myocardial ischemic tolerance in rats

Menopausal status is a risk factor for coronary artery disease death, but the mechanism underlying this association is uncertain. To test whether estrogen ameliorates the effects of acute myocardial ischemia in ways likely to translate into a mortality difference, we compared the response to brief (6-min) and prolonged (45-min) coronary occlusion in vivo in five groups (each n = 16) of rats: 17beta-estradiol replacement; male rats supplemented with estradiol for 6 wk; normal males; and normal females.