Objective:To explore the establishment of radiation-induced heart damage (RIDH) SD rat models caused by irradiation of 15Gy/3f and the changes in early detection indicators, and evaluate the effect of irradiation combined with recombinant human endostatin (Endostar).Methods:75 adult male SD rats were randomly divided into the blank control group (C group), Endostar group (E group), 25Gy irradiation group (MHD 25 group), 15Gy irradiation group (MHD 15 group) and 15Gy irradiation combined with Endostar group (MHD 15+ E group), respectively. Blood sample was taken to measure the CK, CK-MB, LDH and CRP at 24h, 48h and 15d after corresponding interventions. After cardiac echocardiography at 1, 3 and 6 months, 5 rats in each group were randomly sacrificed and myocardial tissues were collected for HE and Masson staining. Two-way ANOVA was employed for statistical analysis. Results:Compared with group C, myocardial fibrosis were observed in the MHD 15 group at 6 months ( P<0.05), which occurred later than that in the MHD 25 group. Ejection fraction (EF) and fractional shortening (FS) were significantly decreased after 3 months in each irradiation group (all P<0.05), whereas the degree of decrease was similar among all groups (all P>0.05). The expression levels of myocardial enzymes and inflammatory cytokines did not significantly differ among different groups (all P>0.05). Conclusions:In the early stage, exposure to 15Gy/3f irradiation can cause cardiac function damage in SD rat hearts, such as the reduction of EF and FS, and even lead to myocardial fibrosis in the late stage, which is delayed and less severe than high-dose irradiation. Irradiation combined with Endostar has no significant effect on radiation myocardial injury in rats.

Objective:To investigate the implication of micro RNA-21(miR-21) in Endostar combined with X-ray irradiation of cardiac fibroblasts (CF).Methods:Rat CFs were used in this experiment and been divided into the blank control group, 10 Gy X-ray irradiation group, Endostar group, 10 Gy X-ray+ Endostar group, 10 Gy X-ray+ Endostar+ NC mimic group (negative control 1), 10 Gy X-ray+ Endostar+ miR-21 mimic group, 10 Gy X-ray+ Endostar+ NC inhibitor group (negative control 2) and 10 Gy X-ray+ Endostar+ miR-21 inhibitor group. The proliferation of CF was determined by Methyl thiazolyl tetrazolium (MTT) assay. The expression level of Collagen Ⅰ protein was analyzed by Western blot. The expression levels of Collagen Ⅰ and miR-21 mRNA were assayed by real-time quantitative polymerase chain reaction (q-PCR).Results:In the 10 Gy X-ray+ Endostar+ miR-21 mimic group, the CF proliferation, Collagen Ⅰ and miR-21 mRNA were increased significantly compared with those in the blank control group, 10 Gy X-ray+ Endostar group, and negative control group 1 (all P<0.05). In the 10 Gy X-ray+ Endostar+ miR-21 inhibitor group, the CF proliferation and expression levels of Collagen Ⅰ mRNA were decreased significantly compared with those in the blank control group, 10 Gy X-ray+ Endostar group and negative control group 2(all P<0.05). Conclusions:The CF proliferation and Collagen Ⅰ expression are increased when the expression level of miR-21 gene is simulated. When inhibiting the expression of miR-21 gene, the CF proliferation and Collagen Ⅰ expression are reduced.