Relationship between expression of Smad and ventricular remodeling after myocardial infarction in rats

Objective To investigate the relationship between expression of Smad3、Smad7 and ventricular remodeling in rats after myocardial infarction.Methods Myocardial infarction was induced by left anterior descending coronary artery ligation in rats(n=11)and sham-operated rats were used as control(n=10).The rats were sacrificed 8 weeks later. Heart weight/ body weight(HW/ BW), mean blood pressure,left ventricular end diastolic pressure(LVEDP),collagen content in the un-infarcted area were examined. The mRNA levels of transforming growth factor (TGF)β_1, Smad 3, Smad7 were determined by RT-PCR.Result Compared with controls,the level of HW/BW,LVEDP and collagen content were significant increased. The mRNA expression of TGFβ_1 and Smad3 was significantly increased in areas of myocardial infarction, border of the infarction, interventricular septum and right ventricle. The expression of Smad7 mRNA in these areas was decreased.Conclusion These results indicated that TGFβ_1-Smads signaling was correlated to the ventricular remodeling after myocardial infarction. Smad3 might promote the process while Smad7 inhibit the process.