Figure 4. Effects of estradiol on ischemia/reperfusion arrhythmias in isolated hearts from (A) young and (B) middle-aged female rats. Arrhythmias were produced by 15-min occlusion of the left anterior descending coronary artery in isolated rat hearts followed by reperfusion. ASI = arrhythmia severity index; OVX = ovariectomy. N = 7-12 rats. ^*P < 0.05 vs control group (one-way ANOVA followed by the Bonferroni test).