【作者】 吴刚；

【导师】 杨波；

【作者基本信息】 武汉大学 ， 内科学心血管内科， 2019， 硕士

【摘要】 【目的】观察松属素对心肌缺血损伤中心脏电重构及Cx43蛋白的影响,研究松属素对心肌梗死后心室颤动的作用及其机制,为临床上治疗心肌梗死提供更多的理论基础及依据。【方法】将60只体重200±20克的SD大鼠,根据随机分为3组:假手术组（Sham组,n=20）,心梗组（MI组,n=20）,心梗+松属素组（MI+Pino组,n=20）。使用结扎冠状动脉左前降支（left anterior descending artery,LAD）的方法建立心肌梗死（myocardial infarction,MI）模型。心电图（electrocardiogram,ECG）显示ST段升高并且左室心尖部变得苍白时,证明MI造模成功。Sham组开胸穿线,但不结扎LAD,旷置1小时。MI+Pino组在心肌缺血前30分钟于大鼠尾静脉注射用生理盐水溶解的松属素（5mg/kg）,术后每天（6:00-7:00pm）尾静脉注射松属素（5mg/kg）,连续注射5天。Sham组和MI组大鼠分别用同样的给药方式在同一时间内以等量的生理盐水处理。造模成功后,记录大鼠体表ECG;行超声心动图检查;灌流离体心脏,记录各组心脏电生理指标和心室颤动（室颤,ventricular fibrillation,VF）的诱发率;分离各组大鼠心室肌组织,利用马松染色检测心肌纤维化程度;利用ELISA法检测血浆肿瘤坏死因子（tumor necrosis factor,TNF）-α水平;利用Western blot方法检测心室肌链接蛋白（connexin43,Cx43）的表达。【结果】1.与Sham组大鼠相比,MI组和MI+Pino组大鼠心电图ST段皆有所抬高,且MI组大鼠比Sham组和MI+Pino组大鼠平均心率（Heart rate,HR）快（MI vs Sham组:P<0.01,MI vs MI+Pino组:P<0.05）,QT间期和校正QT间期（QTc）均更长（MI vs Sham组:QT:P<0.05,QTc:P<0.01,MI vs MI+Pino组:QT:P<0.05,QTc:P<0.01）。而Sham组和MI+Pino组大鼠体表心电图指标无显著差异（P>0.05）。2.与Sham组大鼠相比,MI组大鼠左室舒张末内径（left ventricular end diastolic dimension,LVDD）和左室收缩末内径（left ventricular end systolic dimension,LVSD）明显增大（P<0.01）,而左室射血分数（left ventricular ejection fraction,LVEF）和缩短分数（fractional shortening,FS）明显降低（P<0.01）;与MI组相比,MI+Pino组大鼠LVDD和LVDS有所下降（P<0.01）,LVEF有所升高（P<0.01）,而两组间FS差异无统计学意义（P>0.05）。3.在相同周长起搏中,MI组有效不应期（effective refractory period,ERP）小于Sham组（P<0.05）和MI+Pino组（P<0.01）,Sham组ERP与MI+Pino组无明显差异（P>0.05）。与ERP的趋势相反,MI组和MI+Pino组的动作电位时程(action potential duration,APD₅₀和APD₉₀)与Sham组相比延长,且MI组的这些变化显著大于Sham组(APD₅₀:P<0.01,APD₉₀:P<0.01);与Sham组相比,MI显著增大了ALT（P<0.01）,而MI+Pino组与MI组相比ALT有所降低;Burst刺激时,MI组VF诱发率高于Sham组（P<0.01）,而MI+Pino组的VF发生率为30%,且VF的平均持续时间显著短于MI组（P<0.01）,而Sham组和MI+Pino组VF持续时间无明显的统计学差异（P>0.05）。4.MI组与Sham组大鼠心室肌相比,出现更明显的纤维化（P<0.01）,而MI+Pino组心肌细胞纤维化程度有所减轻。5.与MI组相比,Sham组和MI+Pino组大鼠血浆中炎症因子TNF-α水平明显较低（P值均<0.05）,而Sham组与MI+Pino组大鼠之间TNF-α水平无显著差异（P>0.05）。MI组大鼠心室肌组织中Cx43的表达显著低于Sham组（P<0.01）,而MI+Pino组Cx43表达量有所增加,提示松属素可以改善MI后心室肌Cx43蛋白的表达。【结论】松属素可以降低大鼠心肌梗死后心室颤动的发生率,其机制可能是松属素降低心梗后炎症水平、心肌纤维化程度,改善心功能,恢复细胞间隙连接蛋白功能,并减轻心梗后心脏电生理异质性,从而改善心脏组织及电重构,起到抗心室颤动的作用。更多还原

【Abstract】 Objective To study the effect of pinocembrin on cardiac electrical remodeling and Cx43 protein in myocardial ischemic injury,and to explore the effect of pinocembrin on ventricular fibrillation after myocardial infarction and its mechanism in rats,and provide more evidence for clinical treatment of myocardial infarction.Method 60 SD rats weighing 200±20g were divided into three groups according to the random number table:sham group（Sham group,n=20）,MI group（MI group,n=20）,and MI+Pinocembrin group（MI+Pino group,n=20）.Myocardial infarction（MI）model was established by ligation of the left anterior descending artery（LAD）of the coronary artery.The ligation was confirmed successful when the ST segment was elevated on the electrocardiogram（ECG）and the anterior wall of the left ventricular apex turned pale.The Sham group was operated with the same protocol,except the coronary artery was not ligated.In the MI+Pino group,the rats were treated with Pinocembrin（5mg/kg in saline）was administrated intravenously 30 min before the LAD ligation,then intravenous administration of Pinocembrin were continuously performed daily（6:00-7:00 pm）in 5 days following surgery,also Sham group and MI group treated with saline at the same time and same administration mode.Then,the surface ECG was recorded and echocardiography was performed.The isolated heart was perfused,and the ventricular electrophysiological indexes and VF induction rates of each group were recorded.Masson’s trichrome was conducted to assess myocardial fibrosis.Plasma tumor necrosis factor（TNF）-αlevel was detected by ELISA and Western blot was to detect the expression of connexin43（Cx43）in ventricle.Results 1.The average heart rate（HR）,QT and QTc were elevated in MI group than Sham group（HR:P<0.01,QT:P<0.05,QTc:P<0.01）and MI+Pino group（HR:P<0.05,QT:P<0.05,QTc:P<0.01）.But there were no significant differences between the Sham and MI+Pino groups（P>0.05）.2.Compared with Sham group,left ventricular end diastolic dimension（LVDD）and left ventricular end systolic dimension（LVSD）were significantly increased in MI group（P<0.01）,while left ventricular ejection fraction（LVEF）and fractional shortening（FS）were significantly decreased（P<0.01）.Compared with MI group,MI+Pino group LVDD and LVDS decreased（P<0.01）,LVEF increased（P<0.01）,and FS difference was not statistically significant（P>0.05）.3.In the same circumference pacing,the effective refractory period（ERP）in MI group was smaller than that in Sham group（P<0.05）and MI+Pino group（P<0.01）,and there no significant difference in ERP between Sham group and MI+Pino groups.Contrary to the trend of ERP,the action potential duration(APD₅₀and APD₉₀)in MI group and MI+Pino group were prolonged compared with the Sham group,and these changes in MI group were significantly greater than those in Sham group(APD₅₀:P<0.01,APD₉₀:P<0.01).Compared with the Sham group,MI significantly increased ALT（P<0.01）,and MI+Pino group had lower ALT compared with MI group（P<0.01）.When Burst was stimulated,the VF induction rate in MI group was higher than that in Sham group（P<0.01）.Although the incidence of VF in the MI+Pino group was30%,the mean duration of VF was significantly shorter than that in the MI group（P<0.01）.There was no significantly difference in VF incidence and VF duration between the Sham group and the MI+Pino group（P>0.05）.4.Compared with the Sham group,the ventricular myocardium in MI group showed significant fibrosis（P<0.01）,while the myocardial fibrosis level in MI+Pino group decreased.5.Compared with the MI group,plasma TNF-αlevels were significantly lower in Sham group（P<0.05）and MI+Pino group（P<0.05）,but there was no significant difference between Sham group and MI+Pino group.The expression of Cx43 in the ventricular myocardium of MI group was significantly lower than that in Sham group（P<0.01）,while the expression of Cx43 in MI+Pino group was increased,indicating that pinocembrin can up regulate the expression of Cx43 in the ventricular myocardium after MI.Conclusion Pinocembrin can reduce the incidence of ventricular fibrillation after myocardial infarction in rats.The mechanism may be that pinocembrin reduces myocardial fibrosis,improves cardiac function,restores intercellular junction protein function,and reduces cardiac electrophysiological heterogeneity after myocardial infarction,thereby improving cardiac tissue and electrical remodelling,thus prevents ventricular fibrillation.更多还原