To observe the effect of Bushen Huoxue Formula（补肾活血方）on myocardial fibrosis and TGF-β1/Smads signaling pathway in rats with heart failure after myocardial infarction.

120 male SD rats aged 12 weeks were purchased and 20 were selected as the sham surgery group using the random number method. The remaining 100 rats underwent anterior descending coronary artery ligation, combined with starvation and exhaustive swimming to create a heart failure model after myocardial infarction. A total of 80 model rats were randomly divided into a model group, a Western medicine group, a Chinese medicine high dose group, a Chinese medicine medium dose group and a Chinese medicine low dose group. The rats in the Chinese medicine high, medium and low dose groups were given Bushen Huoxue Formula by gavage at a concentration ratio of 4∶2∶1. The western medicine group was given a suspension of sacubitril and valsartan sodium tablets by gavage. The model group and sham surgery group were given an equal amount of distilled water by gavage. After 4 weeks of continuous medication, ultrasound was used to detect the left ventricular end systolic diameter（LVESD）, left ventricular end diastolic diameter（LVEDD）, left ventricular ejection fraction（EF）and left ventricular short axis shortening rate（FS）in six groups. Masson staining was used to observe the degree of myocardial fibrosis in the six groups and the collagen volume fraction（CVF）was measured. Western blotting（WB）was used to measure the protein expression levels of TGF-β1, p-Smad2, p-Smad3, Collagen Ⅰ and Collagen Ⅲ in the myocardial tissue of the six groups. Fluorescence quantitative polymerase chain reaction（PCR）was used to detect the mRNA expressions of Smad6 and Smad7 in the myocardial tissue of the six groups.

After 4 weeks of medication, compared with those of the sham surgery group, the levels of LVESD and LVEDD of the model group increased, while the levels of EF and FS decreased. The myocardial structure was disordered, CVF increased, and the protein expressions of TGF-β1, p-Smad2, p-Smad3, Collagen Ⅰ and Collagen Ⅲ in myocardial tissue increased. The mRNA expressions of Smad6 and Smad7 decreased（P<0.01）. Compared with those of the model group, the levels of LVESD and LVEDD of rats in the western medicine group and the Chinese medicine low, medium and high dose groups were reduced, while the levels of EF and FS were increased. The myocardial structure was neat, CVF was reduced, and the protein expressions of TGF-β1, p-Smad2, p-Smad3, Collagen Ⅰ and Collagen Ⅲ in myocardial tissue was reduced. The expressions of Smad6 mRNA and Smad7 mRNA were increased（P<0.05 or P<0.01）. Compared with the Chinese medicine high dose group, the Chinese medicine medium dose group showed an increase in the levels of LVESD and LVEDD, a decrease in the levels of EF and FS, an increase in the protein expressions of TGF-β1, p-Smad2, p-Smad3, Collagen Ⅰ and Collagen Ⅲ in myocardial tissue, and a decrease in mRNA expressions of Smad6 and Smad7（P<0.01）. Compared with the Chinese medicine medium dose group, the Chinese medicine low dose group showed an increase in the levels of LVESD and LVEDD, a decrease in the levels of EF and FS, an increase in the protein expressions of TGF-β1, p-Smad2, p-Smad3, Collagen Ⅰ and Collagen Ⅲ in myocardial tissue, and a decrease in mRNA expressions of Smad6 and Smad7（P<0.01 or P<0.05）.

Bushen Huoxue Formula can improve myocardial fibrosis in rats with heart failure after myocardial infarction, and its mechanism of action may be related to the inhibition of TGF-β1/Smads activation by Bushen Huoxue Formula.