Protection from Myocardial Reperfusion Injury by Acute Administration of 17 β-Estradiol

Although several studies have demonstrated that chronic exposure to estrogen appears to be cardioprotective, acute circulatory effects of estrogen are largely unknown. Therefore, we studied the effects of acute administration of 17 β-estradiol in myocardial ischemia/reperfusion. Cats were subjected to 90 min of left anterior descending coronary artery (LAD) occlusion and 270 min of reperfusion (MI/R). Either the estrogenic steroid, 17 β-estradiol or its non-estrogenic isomer, 17 α-estradiol was administered (i.v.) 30 min prior to reperfusion at 1 μg/kg bolus followed by a constant infusion lasting the remaining duration of the protocol at 1 μg/kg/h. Control cats were subjected to sham MI/R. Cats treated with 17 β-estradiol demonstrated a marked reduction in cardiac necrosis following MI/R compared to cats receiving 17 α-estradiol or phosphate buffered saline (17±2% v33±1% or 34±4% area of necrosis indexed to the area-at-risk, P