| Objective:This experiment intends to establish a rat model of myocardial ischemia reperfusion injury（MIRI）to evaluate the protective effect of sanguis draconis flavones（SDF）on MIRI in rats;to study the effect of SDF on the expression and distribution of connexin43（connexin43,Cx43）on MIRI in rats.Methods:60 SD rats were adaptively fed for 7 days,and the rats were randomly divided into control group,sham group,MIRI group,and SDF low-dose group(SDF-L group 90mg·kg-1),SDF middle-dose group(SDF-M group 180 mg·kg-1),SDF high-dose group(SDF-H group 360 mg·kg-1),each Each group of 10 rats were given intragastric administration once a day for 14 consecutive days.The Control group,the sham group and the MIRI group were given the same amount of normal saline by gavage.Another 12 SD rats were taken for reserve.A model of myocardial ischemia reperfusion injury was established.The left anterior descending coronary artery（LAD）of the rat was ligated to cause ischemia for 30 minutes,and the ligation was released and reperfusion was performed for 2 hours.An automatic biochemical analyzer was used to detect the serum lactate dehydrogenase（LDH）and creatine kinase isoenzyme（CK-MB）levels in rats;Hematoxylin-eosin（HE）staining was performed to observe the pathomorphologic changes of myocardial tissue in rats.Triphenyl tetrazolium chloride（TTC）staining was used to observe the myocardial infarction area in rats;Terminal deoxynucleotidyl transferase-mediated d UTP-biotin nick end labeling assay（TUNEL）was used to detect myocardial cell apoptosis;The expression and distribution of Cx43 in myocardial tissue were detected by immunohistochemistry;Quantitative real-time PCR（RT-PCR）was used to determine the expression level of Cx43m RNA in myocardial tissue.Results:（1）Compared with Control group and Sham group,the levels of serum LDH and CK-MB,myocardial infarction area and cardiomyocyte apoptosis rate were increased in MIRI group,SDF-L group,SDF-M group and SDF-H group,while the expression of Cx43 and Cx43m RNA in myocardial tissue of rats were decreased（P<0.05）.（2）Compared with the MIRI group,the levels of serum LDH and CK-MB,myocardial infarction area,and cardiomyocyte apoptosis rate in the SDF-L,SDF-M and SDF-H groups were reduced,and the expression of Cx43 and Cx43m RNA in myocardial tissue of rats were increased（P<0.05）.（3）HE staining under light microscope showed that the morphology of cardiomyocytes in Control group and Sham group was regular,neat and dense,the muscle fibers were intact,and there was no edema,degeneration and necrosis of cardiomyocytes and no inflammatory cell infiltration.In MIRI group,the structure of cardiomyocytes was incomplete,myocardial fibers were swollen,broken and disordered,myofilament was dissolved,cardiomyocytes were necrotic,interstitial edema and inflammatory cell infiltration.The symptoms of myocardial injury in the sanguis draconis flavones group were significantly reduced compared with MIRI group.（4）Observing the distribution of Cx43 under light microscope,it can be seen that the control group and the Sham group have strong positive expression of Cx43 in the myocardium.They are distributed in strips and arranged regularly.Most of them are distributed in the intercalary disc,and a few are located at the junction of the side of the myocardium.The expression of Cx43 in the MIRI group was significantly reduced at the intercalary disc,and the distribution was uneven,mainly concentrated at the junction of the side of the myocardium.The expression of Cx43 at the intercalary disc in the SDF-L group,SDF-M group and SDF-H group was significantly higher than that in the MIRI group.Conclusion:（1）Sanguis draconis flavones can alleviate myocardial ischemia reperfusion injury in rats.（2）Sanguis draconis flavones may reduce myocardial ischemia reperfusion injury in rats by affecting the expression and distribution of myocardial Cx43. |
