急性心肌缺血再灌注家兔模型左心室三层心肌间Cx43表达异质性的改变

Changes of transmural heterogeneity of Cx43 expression in acute myocardial ischemia reperfusion

目的:观察急性心肌缺血再灌注(MIR)三层心肌间跨室壁缝隙连接蛋白43(Cx43)分布的差异,探讨MIR易发恶性室性心律失常(MVA)的生理机制。方法:将20只家兔随机分成MIR组和假手术组,每组10只。MIR组建立MIR模型,假手术组同等条件饲养,未进行任何处理。检测并比较两组家兔左心室三层心肌的单相动作电位复极90%时程(APD_(90))、跨室壁复极离散度(TDR)以及Cx43蛋白(Cx43-pro)和mRNA(Cx43-Cq)的表达。结果:1.MIR组三层心肌APD_(90)和TDR较假手术组显著增加,差异有统计学意义(P<0.05),说明MIR跨室壁复极离散显著增加。2.MIR组三层心肌的Cx43-pro表达与假手术组均有所降低(P均<0.05),差异有统计学意义,但ΔCx43-pro表达较假手术组显著增加,差异有统计学意义(P<0.05),表明MIR增加了家兔跨室壁Cx43蛋白表达的异质性。3.与假手术组比较,MIR三层心肌Cx43-Cq mRNA表达均明显降低(P均<0.05),但ΔCx43-CqmRNA表达显著增加(P<0.05),表明MIR增加了跨室壁Cx43mRNA表达的异质性。结论:MIR左心室三层心肌间Cx43表达差异增大可能是导致心肌横断面上复极时程进一步离散易发MVA的原因。

Objective： To observe changes of transmural heterogeneity of Cx43 protein among three myocardial layers and to explore physiological mechanisms of malignant ventricular arrhythmia （MVA） in myocardial ischemia reperfusion （MIR）. Methods： Twenty rabbits were randomly divided into MIR group （n= 10） and sham group （n= 10）. In the MIR group, MIR rabbits were established. 90 % monophasic action potential repolarization duration （APD90 ）, transmural dispersion of re- polarization （TDR） and Cx43 protein（Cx43-pro） and mRNA（Cx43-Cq） expression among three myocardial layers were meas- ured in both groups. Results： 1. Compared with APDg0 and TDR among three myocardial layers in the sham group, those in the MIR group were significantly increased （P〈0.01）, which showed that transmural dispersion of repolarization increased signifi-cantly in MIR. 2. Compared with those in the sham group, all three myocardial Cx43-pro significantly decreased（P〈0.05）and ACx43-pro obviously increased（P〈0.05）in the MIR group which indicated transmural expression heterogeneity of Cx43 pro tein enlarged in MIR. 3. Cx43-Cq in all myocardium were significantly reduced（P〈0.05）and ACx43-Cq was obviously increased （P〈0.05）in the MIR group compared to those in the sham group, which proved that transmural heterogeneity of Cx43 mRNA raised in MIR. Oonclusion： Transmural heterogeneity of Cx43 expression among three myocardial layers in MIR significantly in- creased, which may enlarge dispersion of repolarization and prone to MVA.