Role Of MiRNA-133a In The Anti-apoptotic Effect Of Postconditioning

Object:Ischemia and reperfusion injury (1/R) is the major pathological leading to ischemic cardiomyopathy and after cardiac surgery ventricular dysfunction Therefore, looking for some effective myocardial protection measures in order to reduce myocardial ischemia and reperfusion injury is very significance. Postconditioning (PostC) is composed of to brief cycles ischemia-reperfusion at the onest reperfusion, wihich could significantly reduce reperfusion myocardial infarct size, and inhibition of cardiomyocyte apoptosis and inflammatory. Subsequent studies showed that PostC is cardioprotective in patients undergoi ng PCI for acute myocardial infarction or undergoing cardiac surgery for tetr alogy of Fallot. However, the detailed mechanism to deal with myocardial prote ction after ischemia is not very clear. of miRNA-133a in myocardial tissue-speci fic expression and broad participation in a variety of biologicaleffects ofstress my ocardial cells, proliferation, differentiation and apoptosis, and myocardial ischemia and reperfusion injury and play an important role in the mechanism of ischemic preconditioning in myocardial protection. This project intends to in vivo myocar dial ischemia and reperfusion injury model to observe the mechanism of ischemi a-reperfusion injury the PostC of myocardial protection, to explore miRNA-133a on the expression of Bcl-xl/s expression regulatory role in PostC anti-apoptoti cmechanism.Methods:Fourty eight healthy adult male wistar rats were divided into six groups.(1) Sham group, place suture under the coronary artery, but do not to occlude the artery,after24h, take myocardial specimens (2) I/R group, ische mia30min and reperfusion24h, take myocardial specimens (3) PostC group, after30min ischemia,comprised3cycles of10seconds of reperfusion folio wed by10seconds ischemia,then reperfused24h. take myocardial specimens (4) PostC+antagomiR group, inject antagomiR-133a into intromyocardial50μl, after30min ischemia,comprised3cycles of10seconds of reperfusion follow ed by10seconds ischemia,then reperfused24h, take myocardial specimens (5) PostC+Nacl group, inject0.9%NaCl into intromyocardial50μl, after30min ischemia,comprised3cycles of10seconds of reperfusion followed by10sec onds ischemia,then reperfused24h, take myocardial specimens (6) PostC+scram ble group, inject scramble control into intromyocardial50μl, after30min isch emia,comprised3cycles of10seconds of reperfusion followed by10second s ischemia,then reperfused24h, take myocardial specimens.TTC-Evans blue sta ining was used to detect myocardial infarct size. TUNEL staining was used t o analysis myocardial apoptosis index, Immunohistochemical method (IM) wa s detected expression of Bcl-xl, of Bel-xs protein. The expression of miRNA-133a, Bcl-xl mRNA, Bcl-xs mRNA was determined by Real-time PCR and In Situ Hybrization.Results:Compared with I/R group, the area of myocardial infarction and car diomyocyte apoptotic index decreased(TTC44.83±5.20VS30.47±1.89,P<0.05; TUNEL42.6±5.4VS31.3±3.3, P<0.05)in PostC group, the expression of miR NA-133a, Bcl-xl mRNA increased(miRNA-133a RT-PCR3.12v0.09VS1.36±0.06,P<0.05;Bcl-xl mRNA RT-PCR3.52±0.49VS1.31±0.56,P<0.05), while the expression of Bcl-xl protein increased (3.14±0.17VS0.27±0.07,P<0.05). Comp ared with I/R group,the expression of Bcl-xs protein incresead(0.18±0.03VS3.42±0.13,P<0.05) in PostC group Whereas, compared with PostC group these index has no change in PostC+ns group and PostC+scramble group. Specific i nhibitors of miRNA-133a antagomiR-133a, PostC reduce myocardial infarct size as well as antiapoptotic effects disappear, of miRNA-133a significantly reduced thele vel of expression of Bcl-xl mRNA expression insignificant upregulation of Bcl-xs mRNA expression levels, while Bcl-xs protein expression was significantly upr egulatedthe expression of Bcl-xl in protein expression levels were significantly red uced.Conclusion:PostC can significantly increase of miRNA-133a expression, may regulate the expression of Bcl-xl/s expression regulating myocardial apoptosis.