RESUMO
Objective:To evaluate the effect of electroacupuncture (EA) on electrophysiological characteristics of ventricular myocardium during myocardial ischemia-reperfusion (I/R) in rats.Methods:Twenty-four clean-grade healthy adult male Sprague-Dawley rats, weighing 280-320 g, were divided into 3 groups ( n=8 each) using a random number table method: sham operation group (group SH), I/R group and group EA.The model of myocardial I/R injury was established by ligating the left anterior descending branch of coronary artery for 30 min followed by 30-min reperfusion in anesthetized rats.Bilateral Neiguan acupoints in forelimbs were stimulated for 30 min during the period of reperfusion in group EA.Heart rate (HR), monophasic action potential amplitude (MAPA), maximum depolarization rate (V max), and monophasic action potential duration at 90% repolarization (MAPD 90) were recorded.The development of arrhythmias and arrhythmias score were recorded during reperfusion. Results:Compared with group SH, HR was significantly decreased, MAPA and V max were decreased, MAPD 90 was prolonged, and the incidence of ventricular premature beat, ventricular tachycardia and ventricular fibrillation and arrhythmias score were increased at T 1, 2 in I/R and EA groups ( P<0.05). Compared with group I/R, HR was significantly increased, MAPA and V max were increased, MAPD 90 was shortened, and the incidence of ventricular tachycardia and ventricular fibrillation and arrhythmias score were decreased at T 2 in EA group ( P<0.05). Conclusion:EA can accelerate myocardial depolarization and shorten repolarization, thus decreasing the occurrence of reperfusion arrhythmia in rats.
RESUMO
Objective:To evaluate the effect of electroacupuncture postconditioning on the expression of microRNA-1 (miRNA-1) in rats with arrhythmias induced by myocardial ischemia-reperfusion (I/R).Methods:Twenty-four clean-grade healthy adult male Sprague-Dawley rats, aged 2-3 months, weighing 280-320 g, were divided into 3 groups ( n=8 each) using a random number table method: sham operation group (S group), I/R group and electroacupuncture postconditioning group (EP group). The model of myocardial reperfusion arrhythmia was established by ligating the left anterior descending branch of coronary artery for 30 min followed by 30-min reperfusion in anesthetized rats.The artery was only isolated without ligation after thoracotomy in group S. Bilateral Neiguan acupoints were stimulated for 30 min starting from the time point immediately after reperfusion in EP group.The occurrence of arrhythmia during reperfusion was recorded.The rats were sacrificed at 30 min of reperfusion, and hearts were removed for examination of the pathological changes of the myocardium and for determination of miRNA-1 expression (by quantitative real-time polymerase chain reaction) and expression of Kir2.1 and connexin 43 (Cx43) (by Western blot). Results:Compared with S group, the incidence of arrhythmia was significantly increased, the expression of miRNA-1 was up-regulated, and the expression of Kir2.1 and Cx43 was down-regulated in I/R and EP groups ( P<0.05). Compared with I/R group, the incidence of arrhythmia was significantly decreased, the expression of miRNA-1 was down-regulated, and the expression of Kir2.1 and Cx43 was up-regulated in EP group ( P<0.05). The pathological changes of myocardium were accentuated in I/R and EP groups when compared with S group, and the pathological changes were significantly attenuated in EP group when compared with I/R group. Conclusion:The mechanism by which electroacupuncture postconditioning reduces the occurrence of reperfusion arrhythmia is related to up-regulation of Kir2.1 and Cx43 expression after down-regulation of miRNA-1 expression in rats.