| Objective: To investigate the effect of flavonoid apigenin on myocardial cell apoptosis and bcl-2,bax and Caspase-3 expression in experimental rats with myocardial ischemia and reperfusion (ischemia / reperfusion, I / R) and analysis the protetive effects on myocardial ischemia reperfusion injury .Methods: The myocardial ischemia-reperfusion injury model was established through occluding the left anterior descending branch of coronary artery for 45 min and later reperfusing 2 hours. Sixty-four rats were randomly divided into eight groups: normal(Normal) group,sham operation(Sham) group, saline ischemia-reperfusion(NS) group, solvent control(Sol) group, metoprolol(Meto) control group, apigenin low, medium and high dose (1 mg·kg-1, 2 mg·kg-1, 4 mg·kg-1) treatment group (Api1, Api2, Api4). At the same time, we observed the duration of reperfusion arrhythmias and calculated the scores of reperfusion arrhythmias. Heart was quickly removed after 2 h reperfusion,We measured nitric oxide though chemical analysis method and detected nitric oxide synthase activity with 721 spectrophotometer; We used 1% Evean Blue and 2,3,5- triphenyltetrazolium chloride(2,3,5-triphenyltetrazolium chlorid, TTC) staining to evaluate myocardial damage area and infarct size; We used TUNEL assay to identify apoptosis of myocardial cells in situ labeling; Bcl-2,Bax and Caspase-3 protein expression were tested by immunohistochemical staining method; myocardial injury degree was observed though histopathological biopsy; the expression levels of Bcl-2 mRNA and Bax mRNA were detected by reverse transcriptase-polymerase chain reaction (RT-PCR).Results:⑴The NO contents detected in different doses of Apigenin groups were significantly higher than in saline ischemia-reperfusion group (groups) (P <0.05) , and Api4 group was the highest;⑵The activities of T-NOS and cNOS of myocardial tissue samples detected in the different doses of Apigenin groups were significantly higher than in saline ischemia-reperfusion group (P <0.05), and Api4 group was the highest. There were no differences in activity of iNOS detected among the groups, and the activity of iNOS was much lower than cNOS.⑶Apigenin in each dose group and NS group, dose-dependent manner decreased (P <0.05).⑷Api4 group and the Meto group reduced the total scores and shorten (shortened) the duration of arrhythmia, and have statistically significances to NS group or the Sol group(P <0.05), however, NS group and the Sol group were no statistically significan(tP >0.05), Api4 group compared with Meto group were no statistically significant(P >0.05).⑸Myocardial cell apoptosis rate in apigenin groups with different dose were significantly lower than that of NS group (P <0.05), and reduced dose-dependently.⑹Apigenin increased Bcl-2 protein expression(P <0.05) and reduced dose-dependently Bax and Caspase-3 protein expression (P <0.05) in rats with myocardial ischemia reperfusion.⑺Pathological damage of myocardial cells in apigenin groups with different dose were significantly lighter than that of NS group (P <0.05).⑻Comparing to the NS group, the expression of Bcl-2 mRNA was dose-dependently increased, and the expression of Bax mRNA was dose-dependently reduced in apigenin groups (P <0.05).Conclusion:⑴The protetive effect on apigenin drugs preconditioning in rats with myocardial ischemia reperfusion injury in rats may related to NO production.⑵Apigenin can prevent the duration of reperfusion arrhythmias,low the scores, reduction in the apoptosis of cardiomyocytes and shorten myocardial MIS after reperfusion. Therefore,apigenin,plays a protective role on myocardial ischemia reperfusion injury.⑶The mechanism that Apigenin against myocardial ischemia reperfusion cells apoptosis is involved in decreasing the expression of Bax, Caspase-3 and increasing the expression of Bcl-2 in rats.
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