摘要
目的探讨大鼠急性心肌缺血时交感神经刺激对室性心律失常的影响及其潜在的机制。方法结扎大鼠冠状动脉前降支制备急性心肌缺血模型后随机分组作为心肌缺血组（MI组，n=25）、缺血＋交感神经刺激组（MI—SS组，n=25）、交感神经刺激＋酚妥拉明＋缺血组（MI—SS—Phen组，n=15）、交感神经刺激＋普萘洛尔＋缺血组（MI—SS—Prop组，n=15）和假手术组（SO组，n=20）。心电图监测室性心律失常的发生。蛋白免疫印记法（Western blot）检测缝隙连接蛋白43（Cx43）的磷酸化蛋白及总量表达变化。逆转录聚合酶链反应（PCR）分析Cx43 mRNA的表达变化。免疫荧光观察Cx43表达分布情况。结果结扎冠状动脉30min内MI、MI—SS和MI—SS-Phen组分别有1、3和2只大鼠死于心室颤动（室颤）；MI—SS组室性心动过速（室速）／室颤发生率（80．0％，20／25）较MI组（52．0％，13／25）明显增加（P〈0．05）；与MI—SS组相比，普萘洛尔明显阻断了交感神经刺激促室速／室颤发生的作用（13．3％，2／15，P〈0．05）。冠状动脉结扎30min后，MI组磷酸化Cx43的比例较SO组显著降低（P〈0．05），但其总量并未减少（P〉0．05）。与MI组相比，MI—SS组磷酸化Cx43的比例明显增加（P〈0．05），同时其蛋白总量的表达显著降低（P〈0．05）；普萘洛尔显著抑制了交感神经刺激导致的Cx43蛋白降解的作用，同时抑制了缺血引起的Cx43脱磷酸化（P〈0．05）。MI和MI-SS组Cx43mRNA表达均较SO组显著减少（P〈0．05）。免疫荧光结果显示，与SO组相比，MI组Cx43由端-端连接转化为侧-侧连接，而MI—SS组Cx43分布明显紊乱，不能分辨出Cx43的分布模式。结论交感神经刺激能够促进室性心律失常的发生，可能主要与β肾上腺素受体的激活从而促进了Cx43的降解有关。
Objective To investigate the effect and mechanism of sympathetic nerve stimulation on ventricular arrhythmias during acute myocardial ischemia （MI） in rats. Methods One hundred rats were randomly assigned into five groups ： myocardial ischemia with sympathetic nerve stimulation （ MI-SS, n = 25 ）, sham-operation treated （ SO, n = 20 ） , myocardial ischemia with sham stimulation （ MI, n = 25 ）, myocardial ischemia with sympathetic nerve stimulation and phentolamine （MI-SS-Phen, n = 15 ）, myocardial ischemia with sympathetic nerve stimulation and propranolol （MI-SS-Prop, n = 15 ）. Ventricular arrhythmias were monitored by an electrocardiogram. Western blot and RT-PCR were used to analyze Cx43 protein and Cx43 mRNA expression, respectively. Immunofluorescence analysis was used for observing the change of Cx43 protein distribution. Results There were 1,3 and 2 rats deathing due to ventricular fibrillation in the MI,MI-SS and MI-SS-Phen groups,respectively. During the 30 min ligation,the incidence of ventricular tachycardia/fibrillation （VT/VF） in the MI-SS group （80. 0% ,20/25） was significantly higher than that in the MI group （52. 0% ,13/25 ,P 〈 0. 05） ; however,VT/VF was significantly suppressed in the MI-SS-Prop group （ 13.3% ,2/15,P 〈 0. 05 ）.After the 30 min ligation, Cx43 protein was significantly decreased in the MI-SS and MI-SS-Phen groups （ P 〈 0. 05 ） but not in the MI and MI-SS-Prop groups （P 〉 0. 05 ） compared with that in the SO group. The percentage of the phosphorylated Cx43 protein in the MI group was significantly decreased than that in the SO group （P 〈 0. 05）. However,the dephosphorylation of Cx43 protein was prevented in the MI-SS, MI-SS-Phen and MI-SS- Prop groups （ all P 〈 0. 05 ）. Meanwhile, Cx43 mRNA contents in the MI and MI-SS groups decreased significantly compared with that in the SO group （P 〈 0. 05 ）. Immunofiuorescence confirmed that ischemia could induce the distribution changes of Cx43 and sympathetic nerve stimulation could promote Cx43 degradation which has resulted in derangement of Cx43 distribution during acute MI. Conclsion The present study demonstrates that the pro-arrhythmic effect of sympathetic nerve stimulation may be exerted by activating β-adenrenoceptor to promote the degradation of Cx43 protein during acute MI.
出处
《中华心律失常学杂志》
2008年第2期121-125,共5页
Chinese Journal of Cardiac Arrhythmias
基金
武汉市学科带头人计划资助项目（200750730309）
