左西孟旦对大鼠急性心肌梗死后心肌纤维化及心功能的影响

Effects of levosimendan on myocardial fibrosis and cardiac function following myocardial infarction in rats

目的探讨左西孟旦对心肌梗死(myocardial infarction,MI)大鼠心肌纤维化的影响及其作用机制。方法通过结扎大鼠左冠状动脉前降支建立MI模型。30只存活的MI大鼠随机分为模型组和左西孟旦组(Levo组),每组15只。假手术组(n=10)的大鼠接受相同的外科手术,只是不进行动脉结扎。Levo组胃灌注左西孟旦4.67μg·kg-1·d-1治疗28 d。假手术组和模型组大鼠同时给等量蒸馏水。采用二维超声心动图评价心功能,Masson-trichrome评价心肌纤维化程度,RT-qPCR检测COL1A1、COL3A1基因表达,Western blot检测SIRT1/TGF-β1/Smad3信号通路蛋白表达。结果超声心动图测量显示,与模型组相比,Levo组大鼠的左室收缩末期内径降低(P<0.05),而射血分数和缩短分数显著升高(P<0.01)。Masson-trichrome显示,左西孟旦治疗可显著减少坏死心肌组织、抑制炎性细胞的浸润并减少胶原蛋白沉积。RT-qPCR分析显示,左西孟旦治疗显著降低了MI大鼠心肌组织中Ⅰ型和Ⅲ型胶原的含量(P<0.01)。Western blot检测显示,左西孟旦治疗可显著上调MI大鼠心肌组织中SIRT1蛋白表达(P<0.01),下调TGF-β1和p-Smad3蛋白表达(P<0.01)。结论左西孟旦具有抗纤维化和心保护作用。这些作用可能通过SIRT1/TGF-β1/Smad3信号通路介导。

Objective To investigate the effect of levosimendan on myocardial infarction(MI)myocardial fibrosis and its mechanism.Methods MI model was induced by ligation of left anterior descending coronary artery.Thirty surviving MI rats were randomly divided into a model group and a Levo group(15 rats in each group).Rats in the sham group(n=10)underwent the same surgical procedure,except for no arterial ligation.Levosimendan(4.67μg·kg^(-1)·d^(-1))was infused into stomach for 28 days in Levo group.At the same time,rats in sham group and model group were given equal amount of distilled water.2D echocardiography was adopted to evaluate the cardiac function.Masson-trichrome were used to evaluate the degree of myocardial fibrosis.The expression of COL1A1,COL3A1 mRNA and SIRT1/TGF-β1/Smad3 signaling pathway proteins were detected by quantitative reverse transcription PCR(RT-qPCR)and Western blot,respectively.Results Compared with the model group,2D echocardiography result showed that the LVED of Levo group decreased significantly(P<0.05),while the EF and FS increased significantly(P<0.01).Masson-trichrome result showed that levosimendan treatment significantly reduced necrosis and the content of collagen deposition and inhibited infiltration of inflammatory cells.RT-qPCR analysis result showed that levosimendan treatment significantly reduced the content of typeⅠand typeⅢcollagen in the heart tissue of MI rats(P<0.01).Western blot showed that levosimendan treatment could significantly up-regulate SIRT1 protein expression and down-regulate TGF-β1(60%)and p-Smad3(47%)protein expression(P<0.01).Conclusions Levosimendan has anti-fibrotic and cardio-protective effects.These effects are potentially mediated by SIRT1/TGF-β1/Smad3 signaling pathway.