Estradiol, Administered Acutely, Protects Ischemic Myocardium in Both Female and Male Rabbits

Area of Science:

• Cardiovascular Science
• Endocrinology
• Pharmacology

Background:

• Chronic estrogen benefits are known, but acute effects of estradiol on myocardium during ischemia-reperfusion are unclear.
• Investigated acute estradiol's impact on myocardial necrosis in male and female animal models.

Purpose of the Study:

• To determine if acute estradiol pretreatment influences myocardial necrosis after coronary artery occlusion and reperfusion.
• To assess estradiol's effects in both male and female rabbits.

Main Methods:

• Intact anesthetized rabbits (male and female) received 17beta-estradiol or water 15 minutes before 30-minute coronary artery occlusion and 4-hour reperfusion.
• Measured myocardial blood flow, heart rate, systemic pressure, and infarct size relative to the ischemic risk zone.

Main Results:

• Estradiol did not alter myocardial blood flow, heart rate, or systemic pressure.
• Estradiol-treated rabbits (both sexes) showed significantly reduced infarct size compared to controls.
• Female estradiol-treated rabbits: 10% infarct vs. 23% in controls (P < .03); Male estradiol-treated rabbits: 16% infarct vs. 31% in controls (P = .03).

Conclusions:

• Acute estradiol administration exerts a protective effect on ischemic myocardium.
• This cardioprotection is independent of changes in myocardial blood flow or hemodynamics.
• Estrogen reduces infarct size in both male and female rabbits following acute coronary artery occlusion.