[Shexiang Tongxin Dropping Pills improve cardiac function in type 2 diabetic rats by promoting angiogenesis]

This study aims to investigate the effect of Shexiang Tongxin Dropping Pills(STDP) on angiogenesis in type 2 diabetic rats. Thirty-two healthy male SD rats were randomized into a control group(n=6) and a type 2 diabetes mellitus(T2 D) group(n=26). The T2 DM rat model was established with a high-fat diet combined with intraperitoneal injection of streptozotocin(STZ). The model rats were randomized into a model group, a metformin group(200 mg·kg~(-1)·d~(-1)), a high-dose STDP group(40 mg·kg~(-1)·d~(-1)), and a low-dose STDP group(20 mg·kg~(-1)·d~(-1)). The corresponding agents were administered continuously for 8 weeks. The cardiac function indexes were detected by ultrasound at the experiment endpoint, and the myocardial pathological changes were observed via hematoxylin-eosin(HE) staining. The myocardial collagen fiber deposition was detected by sirius red staining, the myocardial microvascular density by immunohistochemistry, and the myocardial hypertrophy by immunofluorescence assay. Western blot was employed to measure the protein levels of vascular endothelial growth factor(VEGF), phosphorylated vascular endothelial growth factor receptor 2(p-VEGFR2), angiogenin-1(Ang1), and TEK tyrosine kinase endothelial(Tie2) in the myocardial tissue. Compared with the model group, STDP improved the left ventricular ejection fraction(EF) and fractional shortening(FS)(P<0.05), alleivated the arrangement disorder of myocardial cells and local myocardial fiber rupture. Sirius red staining showed that STDP, especially the high-dose group(P<0.01), repaired the deposition of myocardial collagen fibers in the model group. The results of immunohistochemistry showed that the cluster of differentiation 31(CD31) expression in myocardial tissue of the STDP groups was higher than that of the model group(P<0.01). The immunofluorescence results showed that STDP mitigated the hypertrophy of myocardial cells(P<0.01). Furthermore, STDP up-regulated the protein levels of VEGF, p-VEGFR2, Angl, and Tie2 compared with the model group(P<0.01). In conclusion, STDP can effectively promote angiogenesis and improve cardiac function in type 2 diabetic rats by up-regulating the expression of VEGF, p-VEGFR2, Ang1, and Tie2.