Adjunctive 17β-estradiol administration reduces infarct size by altered expression of canine myocardial connexin43 protein

Background: Traffic of potentially harmful cytosolic messengers through gap junctions might cause increased injury during ischemia. The present study was to determine whether the infarct size-reducing effect of adjunctive estradiol administration prior to reperfusion is associated with an attenuated expression of connexin43 at the border of infarction in a canine model. Methods: Experiments were performed in 48 dogs (n=16 each group), assigned to receive either vehicle (control group), 17β-estradiol administered before coronary occlusion (early group), or 3 min before coronary reperfusion following 60-min ischemia (late group). Changes in the amount of phosphorylated connexin43 were measured by Western blot. Results: Infarct size was significantly larger in the control (38±7% of area at risk) than in the supplemented groups (16±6% in the early group; 16±8% in the late group, P