目的研究心肌梗死(MI)后大鼠心肌Smad7的表达及其与心肌纤维化的关系。方法结扎冠状动脉建立大鼠MI模型,并另设假手术组为对照组。8周后,测定心室的质量/体质量(HW/BW)。以多普勒超声评价心脏功能。以Mallory’s Trichrome染色法检测非梗死区胶原的含量。分别以RT-PCR和Western blot法检测非梗死区左室心肌转化生长因子(TGF)-β1、Smad7 mRNA及蛋白表达的水平。结果与假手术组比较,MI组的HW/BW(P<0.01)、左心室舒张末期内径(LVEDD,P<0.01)、E峰/A峰比值(E/A,P<0.01)、非梗死区胶原的含量(P<0.01)、非梗死区左室TGF-β1mRNA及蛋白的表达(P<0.01)均显著增加;Smad7 mRNA及蛋白的表达(P<0.01)、射血分数(EF,P<0.01)及短轴缩短率(FS,P<0.01)均显著降低。结论MI后大鼠心肌Smad7的表达降低,与MI后的心肌纤维化密切相关。 Objective To investigate the expression of Smad7 in rat myocardium after myocardial infarction (MI) and its relationship with myocardial fibrosis. Methods The rat MI model was established by ligation of the coronary arteries, and sham-operated group was given as control group. After 8 weeks, the ventricular mass / body mass (HW / BW) was determined. Doppler ultrasound to evaluate cardiac function. The Mallory’s Trichrome staining was used to detect collagen content in non-infarcted area. The mRNA and protein expressions of TGF-β1 and Smad7 in non-infarcted area were detected by RT-PCR and Western blot respectively. Results Compared with sham operation group, HW / BW (LVEDD, P <0.01), E / A ratio (P <0.01) (P <0.01). The expression of TGF-β1mRNA and protein (P <0.01) in non-infarcted area was significantly increased, the expression of Smad7 mRNA and protein (P <0.01), ejection fraction <0.01) and short axis shortening (FS, P <0.01) decreased significantly. Conclusions The expression of Smad7 in myocardium of MI decreased after MI, which is closely related to myocardial fibrosis after MI.