缝隙连接蛋白43在老年大鼠缺血性室性心律失常中的作用

Objective To investigate the expression of connexin43 ( Cx43 ) and effect of vagal nerve stimulation (VNS) on ventricular tachyarrhythmias during acute myocardial ischemia( MI )in aged rats. Methods Male Sprague-Dawley ratsAdult group ( ≤ 4 months) and Aged group ( ≥24 months)]:MI (n = 15 ):ligated left anterior descending coronary for 30 minutes; MI-vagal nerve stimulation(VNS) ( n = 15 ); MI-VNS-atropine (0. 5 mg/kg, n = 13 ); MI-VNS-carbenoxolone ( 10 mg/kg, n = 11 ); sham operation (SO, n = 10):without coronary ligation. Ventricular arrhythmias were monitored by an electrocardiogram. Cx43 protein expression was analyzed by Western blot. Results During the 30 minutes ligation,incidences of ventricular tachycardia (VT) and ventricular fibrillation(VF) in aged rats increased significantly compared to those of adult rats ( P ＜ 0. 05 ). VNS did not affect the occurrence of VT and VF ( both P ＞ 0.05 ); however, VNS suppressed the occurrence of irreversible VF ( P ＜ 0. 05 ); both atropine and carbenoxolone ( a gap junction inhibitor) could abolish the effect of VNS on ischemia-induced irreversible VF ( both P ＜0. 05). Ischemia did not result in changes of total Cx43 amount in adult and aged rats compared to that of SO group,respectively. The amount of nonphosphorylated Cx43 was increased markedly in adult and aged rats compared to that of SO group,respectively.Cx43 dephosphorylation induced by ischemia was significantly suppressed by VNS in adult and aged rats( P ＜0. 05 ). However,the amount of total Cx43 of SO group in aged rats was significantly decreased by 50% compared to that of SO group in adult rats ( P ＜ 0. 05 ). Conclusion The present study suggested that the incidence of ischemia-induced ventricular tachyarrhythmias increased markedly and the anti-arrhythmic effect of VNS was decreased significantly in aged rats, which may be associated with reduction of Cx43 protein of ventricle in aged rats.

Effects of Connexin 43 expression on ischemia-induced ventricular arrhythmias in aged rats