Protective effects of estrogen against reperfusion arrhythmias following severe myocardial ischemia in rats.
BACKGROUND
Female sex hormones may have protective effects against arrhythmias, including reperfusion arrhythmias (RAs), but the mechanisms are still not completely known.


RESULTS
Serial changes in rat hearts (rhythm, apoptosis and the its infuencing factors; cardiac vinculin mRNA expression and connexin43 (Cx43) dephosphorylation) were examined during periods of ischemia-reperfusion with and without estrogen treatment. After reperfusion, although the incidence of arrhythmias became higher in both the vehicle-group and estrogen-group, compared with the ischemia period, estrogen prevented reperfusion-induced upregulation of the incidence of arrhythmias, especially ventricular premature beats (VPB) and ventricular tachycardia (VT). The duration of VT and fibrillation, and the number of VPB and VT, were all significantly decreased in the estrogen-group. The expression of cardiac vinculin mRNA decreased significantly in the vehicle-group but not in the estrogen-group. Cx43 dephosphorylation and myocyte apoptosis increased in both groups, but the values for the estrogen-group were all markedly lower than those for the vehicle-group. A selective estrogen receptor (ER) beta agonist prevented reperfusion-induced upregulation of the incidence of both VPB and VT significantly; a selective ERalpha agonist had no significant influence.


CONCLUSIONS
Estrogen can protect the heart against RAs, at least in part, mediated through gap junctions. Upregulation of ERbeta but not ERalpha mediated most of the estrogen-induced cardioprotection against RA.
Wang
Yan
Y
Laboratory Center, Second Affiliated Hospital of Dalian Medical University, Dalian, China.
Wang
Qi
Q
Zhao
Yingnan
Y
Gong
Dezheng
D
Wang
Dongmei
D
Li
Cong
C
Zhao
Henan
H
D000818:Animals; D017209:Apoptosis; D001145:Arrhythmias, Cardiac / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control*; D005117:Cardiac Complexes, Premature / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D018031:Connexin 43 / Q000378:metabolism; D004562:Electrocardiography; D047629:Estrogen Receptor beta / Q000378:metabolism; D004967:Estrogens / Q000627:therapeutic use*; D017629:Gap Junctions / Q000378:metabolism; D015994:Incidence; D008297:Male; D023421:Models, Animal; D015428:Myocardial Reperfusion Injury / Q000150:complications*; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017180:Tachycardia, Ventricular / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D015854:Up-Regulation; D016596:Vinculin / Q000378:metabolism
D018031:Connexin 43; D047629:Estrogen Receptor beta; D004967:Estrogens; D016596:Vinculin