交感神经刺激对大鼠急性心肌缺血时连接蛋白43和室性心律失常的影响

目的 探讨急性心肌缺血时交感神经刺激对缝隙连接蛋白43(Cx43)及对室性心律失常的影响.方法 结扎大鼠冠状动脉前降支制备急性心肌缺血模型后分组,心肌缺血组(25只,MI)、缺血+交感神经刺激组(25只,MI-SNS)、交感神经刺激预处理+缺血组(25只,pSNS-MI)和假手术组(20只,SO).心电图监测室性心律失常的发生.蛋白质印迹法检测缺血心肌Cx43的磷酸化蛋白及总量表达.RT-PCR分析Cx43 mRNA的表达.免疫荧光观察Cx43表达分布情况.结果 MI-SNS组室速/室颤发生率(80.0%)较MI组(52.0%)明显增加(P＜0.05),而pSNS-MI组室速/室颤发生率(20.0%)显著降低(P＜0.05).冠脉结扎30 min后,与MI组相比(46.7%±6.3%),pSNS-MI组(71.2%±7.0%)和MI-SNS组(73.4%±6.7%)磷酸化Cx43的比例均明显增加(均P＜0.05).MI组(1.29±0.14)和pSNS-MI组(1.25±0.13)蛋白总量均与SO组(1.30±0.10)无明显区别(均P＞0.05),但MI-SNS组(0.73±0.12)蛋白总量较SO组明显减少(P＜0.05).结论 交感神经刺激能够促进缺血性室性心律失常的发生,这可能与其促进了Cx43的降解有关;交感神经刺激预处理能够抑制缺血性室性心律失常的发生,其机制可能与交感神经刺激预处理阻止了Cx43的脱磷酸化有关.

Effects of sympathetic nerve stimulation on connexin43 and ventricular arrhythmias during acute myocardial ischemia: experiment with rats

Objective To investigate the effects of sympathetic nerve stimulation(SNS)on eonnexin43(Cx43)and ventricular arrhythmias during acute myocardial ischemia(MI).Methods Ninety five Wistar rats were randomly divided into four groups:MI group(n=25),undergoing:ligation of the anterior descending coronary;MII-SNS group(n=25);undergoing electric stimulation of sympathetic nerve since the beginning of ligation of the anterior descending coronary and lasting till 30 min after the ligation.sympathetic nerve stimulation preconditioning+myocardial isehemia(pSNS-MI) group(n=25),undergoing electric stimulation of sympathetic nerve since the beginning of ligation of the anterior descending coronary that ended just after the ligation;and sham operation(SO)group(n=20),without coronary ligation.Ventricular arrhythmias were monitored by electrocardiography.Westem blotting and RT-PCR were used to detect the protein and mRNA expression of Cx43 respectively.Immunofluorescence analysis Was used to observe the changes of Cx43 protein distribution.Results One and 3 rats died due to ventricular fibrillation in the MI group and MI-SS group respectively.The incidence of ventfieular tachycardia(VT)/VF within 30-minute after ligation in the MI-SNS group Was 80.0％,significant higher than that of the MI group(52.O％,P<0.05).The incidence of Vr/VF within 30-minute after ligafion of the pSNS.MI group was 20.0％,significantly lower than that of the MI-SNS group(P<0.05).30 minutes after the ligation,the percentage of phosphorylated Cx43 of the pSNS.MI and MI.SNS groups were 71.2％±7.0％and 73.4％±6.7％respectively,both significantly higherthanthat of the MI group(46.7％±6.3％)(bothP<0.05).The total contents of Cx43 of the MI and pSNS-MI groups were 1.29±0.14 and 1.25±0.13 respectively.Both similar to that of the SO group (1.30±0.10),both P>0.05],while the total Cx43 content of the MI-SNS group Was 0.73±0.12,significantly lower than that of the SO group(1.30±0.10),P<0.05].The Cx43 mRNA levels of the 3 experimental groups were all significantly lower than that of the SO group(all P<0.05).Immunofluoreseence analysis confirmed tllat ischemia and sympathetic nerve stimulation induced the changes of eonnexin43 distribution and sympathetic nerve stimulation preconditioning inhibited the changes of connexin43 distribution induced by isehemia.Conclusion SNS promotes ventficular arrhythmias by promoting Cx43 degradation,and sympathetic nerve stimulation preconditioning inhibits ventrieular arrhythmias by preventing Cx43 dephosphorylation.