目的:探讨MicroRNA(miR)-451在大鼠心肌缺血/再灌注(I/R)损伤中的作用及其作用机制。方法:将70只SD大鼠随机分为5组:假手术组(SO)、缺血再灌注组(I/R)、腺病毒空载体组(I/R+Ad-GFP)、miR-451上调组(I/R+Ad-miR-451)、miR-451下调组(I/R+Ad-asmiR-451)。心肌注射病毒液(1×1010 pfu/只)或PBS液(150μl/只)后3d建立缺血30min再灌注24h的心肌I/R模型。应用TTC+伊文思蓝双染法测定各组心肌梗死面积百分比,TUNEL法检测凋亡率,Western Blot法测定HMGB1和Caspase 3活化片段含量,应用试剂盒检测血清CK、LDH含量以及心肌组织SOD、MDA含量。结果:再灌注24h后,与SO组相比,I/R组和I/R+Ad-GFP组血清CK、LDH含量明显升高,心肌组织SOD活性降低、MDA含量升高,心肌组织HMGB1及Caspase-3活化片段蛋白含量显著上升,心肌细胞凋亡指数明显增加(以上P<0.05);与I/R组、I/R+Ad-GFP组相比,I/R+Ad-miR-451组血清CK、LDH含量显著下降,心肌组织SOD活性上升、MDA含量下降,心肌组织HMGB1和Caspase-3活化片段蛋白含量下降,心肌梗死面积百分比降低,心肌细胞凋亡指数降低(以上P<0.05);与I/R组、I/R+Ad-GFP组相比,I/R+Ad-asmiR-451组血清CK、LDH含量无明显上升,心肌组织MDA含量及SOD活性无明显变化,心肌组织HMGB1表达含量无明显上升,心肌梗死面积百分比及心肌细胞凋亡指数无显著升高(以上P>0.05),Caspase-3活化片段蛋白含量上升(P<0.05)。结论:MicroRNA-451通过调控HMGB1的表达,减轻凋亡和氧化应激进而减轻心肌I/R损伤。 AIM: To investigate the role of microRNA (miR) -451 in myocardial ischemia / reperfusion (I / R) injury in rats and its mechanism. Methods: Seventy SD rats were randomly divided into 5 groups: sham operation group (SO), ischemia reperfusion group (I / R), adenovirus empty vector group (I / R + Ad-GFP) (I / R + Ad-miR-451) and miR-451 downregulation group (I / R + Ad-asmiR-451). Myocardial I / R model was established after myocardium injection of virus solution (1 × 1010 pfu / mouse) or PBS solution (150μl / mouse) for 30min after reperfusion for 30min. The percentage of myocardial infarction area was determined by TTC + Evans blue staining. The apoptosis rate was detected by TUNEL method. The contents of HMGB1 and Caspase 3 were determined by Western Blot. The contents of CK, LDH and SOD, MDA content. Results: Compared with SO group, the levels of serum CK and LDH in I / R group and I / R + Ad-GFP group were significantly increased after 24h reperfusion, the activity of SOD in myocardium was decreased, the content of MDA was increased, the levels of HMGB1 Compared with I / R group and I / R + Ad-GFP group, the protein content of Caspase-3 activation fragment increased significantly and the apoptosis index of cardiomyocyte significantly increased (P <0.05) Serum levels of CK and LDH were significantly decreased, the activity of SOD in myocardium was increased, the content of MDA was decreased, the protein contents of HMGB1 and Caspase-3 in myocardium were decreased, the percentage of myocardial infarction area was decreased and the apoptosis index was decreased (P <0.05) Compared with I / R group and I / R + Ad-GFP group, serum CK and LDH levels in I / R + Ad-asmiR-451 group did not increase significantly, MDA content and SOD activity in myocardial tissue did not change significantly, HMGB1 expression did not increase significantly, myocardial infarction area percentage and myocardial cell apoptosis index did not increase significantly (P> 0.05), Caspase-3 activation fragment protein content increased (P <0.05). Conclusion: MicroRNA-451 can reduce myocardial I / R injury by regulating the expression of HMGB1, reducing apoptosis and oxidative stress.