Exogenous Hydrogen Sulfide Improves Apoptosis Through CDK₆-E₂F1 Pathway And Improves Myocardial Remodeling In Rats After Acute Myocardial Infarction

Objective:To establish a rat model of acute myocardial infarction by isoproterenol（Iso）,and to investigate the relationship between myocardial remodeling and endogenous H₂S and apoptosis and CDK₆-E₂F1 pathway after acute myocardial infarction.To investigate the role and mechanism of exogenous hydrogen sulfide in inhibiting apoptosis by regulating CDK₆-E₂F1 pathway to improve myocardial negative remodeling after myocardial infarction.Methods:40SD rats were randomly divided into four groups,10 in each group,which were control group（control）,model group（Iso）,H₂S intervention group（Iso+H₂S）,H₂S control group（H₂S）.Rats in the control group were intraperitoneally injected with the same amount of normal saline in the model group.The model group was intraperitoneally injected with Iso（50 mg/kg）daily for 2 days.The H₂S intervention group was intraperitoneally injected with Iso（50 mg/kg）for 2 days.The electrocardiogram and troponin were detected in the group.The H₂S intervention group and the H₂S control group were intraperitoneally injected with NaHS（56μmol/kg）.The control group and the model group were intraperitoneally injected with the same dose of normal saline for 4 weeks.After 4weeks,the heart was measured by color Doppler ultrasound.After the rats were sacrificed,the body weight and heart weight were weighed;Masson staining was used to detect myocardial collagen fiber deposition;Tunel staining was used to observe apoptosis;Immunohistochemistry was used to detect type III collagen fibers;the expression of Col3a1,Col1a2 and GAPDH in myocardial tissue was detected by real-time PCR（RT-qPCR）,and protein expression levels of BAX,Bcl-2,BclXL,Caspase3,Caspase9,Col4a3bp,mmp9,mmp13,TIMP2,TGF-β,GAPDH,CDK₆ and E₂F1 were detected by WB.result:1.Compared with the Control group,the ST segment of the electrocardiogram II lead in the Iso group and the Iso+H₂S group was significantly increased,and the troponin T was significantly increased,indicating that the acute myocardial infarction model was successfully established.2.Compared with the Control group,the HW/BW and the BW values increased of the Iso group（P<0.05）.Compared with the Iso group,the HW/BW values of the Iso+H₂S group and the H₂S group were reduced,and the BW value was reduced（P<0.05）.3.Compared with the Control group,the results of echocardiography showed that the cardiac function of the Iso group was decreased,the LVEDD value and the LVESD value were significantly increased,and the LVFS value was significantly decreased in the Iso group（P<0.05）.Compared with the Iso group,the cardiac function was improved in Iso+H₂S group,the LVEDD value and LVESD value were decreased,and the LVFS value were increased（P<0.05）.4.Compared with the Control group,Masson results showed that the myocardial cells in the Iso group were significantly disordered,and the myocardial collagen fibers were significantly increased.Compared with the Iso group,the myocardial cells in the Iso+H₂S group were arranged neatly and the myocardial collagen fibers were decreased.5.The results of immunohistochemistry showed that the expression of type III collagen in myocardial tissue of Iso group was increased compared with Control group.The expression of type III collagen was decreased in myocardial tissue of Iso+H₂S group compared with Iso group.6.Compared with the Control group,the results of Tunel staining indicated that the myocardial cells in the Iso group were irregular in shape and the nuclei were stained brown.Compared with the Iso group,the myocardial cells in the Iso+H₂S group were relatively regular in morphology and blue in the nucleus.7.Compared with the Control group,RT-qPCR results showed that the expression of Col3a1 and Col1a2 in Iso group was significantly increased（P<0.05）.Compared with Iso group,the expression of Col3a1 and Col1a2 in Iso+H₂S group was significantly decreased（P<0.05）.8.Compared with the Control group,Western Blotting results showed that the expression levels of BAX,BclXL,Caspase3,Caspase9,Col4a3bp,mmp9,mmp13,TGF-β,GAPDH,CDK₆ and E₂F1 were increased in the Iso group（P<0.05）,Bcl-2 and TIMP2expression level were decreased（P<0.05）;compared with Iso group,the expression levels of BAX,BclXL,Caspase3,Caspase9,Col4a3bp,mmp9,mmp13,TGF-β,GAPDH,CDK₆ and E₂F1 were decreased in Iso+H₂S group（P<0.05）,and the expression level of Bcl-2 and TIMP2 were increased（P<0.05）.Conclusion:H₂S could improve the myocardial negative remodeling after myocardial infarction induced by isoproterenol.The mechanism could be related to the inhibition of apoptosis by regulating CDK₆-E₂F1 pathway.