运动预干预对心肌缺血/再灌注大鼠心肌氧化应激及线粒体融合和分裂的影响

Effects of Exercise Pre-Intervention on Myocardial Oxidative Stress and Mitochondrial Fusion and Division in Rats with Myocardial Ischemia/Reperfusion

目的:探讨8周跑台运动预干预对心肌缺血/再灌注(I/R)大鼠心肌纤维结构及心脏功能的影响,并通过检测心肌组织氧化应激水平和动力相关蛋白1(Drp1)及视神经萎缩蛋白1(OPA1)的表达,探讨跑台运动预干预影响I/R大鼠心脏功能的可能机制。方法:将64只雄性成年SD大鼠随机分为4组,假手术组(sham)、假手术运动组(EX)、心肌缺血/再灌注组(I/R)及运动预干预+心肌缺血再灌注组(I/R+EX),每组16只,随后对EX组及I/R+EX组大鼠进行8周中等强度的跑台运动预干预。运动结束后,通过结扎左冠脉动脉前降支缺血30 min,再灌注120 min的方法建立I/R模型,采用BL-420S生物机能实验系统监测大鼠缺血前、缺血30 min、再灌注120 min 3个时间点的左室收缩压(LVSP)、左室舒张末期压力(LVDEP)及左室内压上升和下降的最大变化速率(±dp/dtmax),于再灌注120 min后采集心肌组织,然后HE染色观察心肌纤维结构的变化,黄嘌呤氧化酶法检测大鼠心肌组织超氧化物歧化酶(SOD)活性、硫代巴比妥酸法检测心肌组织丙二醛(MDA)水平,westernblot实验测定心肌组织Drp1及OPA1蛋白表达。结果:(1)与sham组比较,I/R组大鼠心肌组织呈现明显的病理改变,LVSP、+dp/dtmax及-dp/dtmax(P<0.01)均显著下降,LVDEP(P<0.01)显著增加;心肌组织SOD活性(P<0.01)及OPA1蛋白表达(P<0.01)均明显下降,MDA水平(P<0.01)及Drp1蛋白表达(P<0.01)均明显增加。(2)8周跑台运动预干预可显著改善I/R大鼠的心肌组织病理变化及心脏功能,与I/R组比较,I/R+EX组大鼠心肌组织SOD活性(P<0.05)及OPA1蛋白表达(P<0.01)均显著增加,MDA水平(P<0.01)及Drp1蛋白表达(P<0.05)均显著下降。结论:运动预干预对大鼠心肌缺血/再灌注损伤具有保护作用,可能与此运动维持线粒体分裂与融合的动态平衡,减轻I/R诱导的心肌氧化应激损伤有关。

Objetive:Explore the possible mechanism of 8-week treadmill exercise pre-intervention on myocardial fiber structure and cardiac function in myocardial ischemia-reperfusion(I/R)rats by detecting oxidative stress level,dynamin-related protein 1(Drp1)and optic atrophy 1(OPA1)expression in myocardial tissue.Methods:64 SD rats were randomly allocated into 4 groups(n=16):sham group,exercise group(EX),myocardial ischemia-reperfusion group(I/R group)and myocardial ischemia-reperfusion with exercise group(I/R+EX).Then,the rats in EX and EX+I/R groups were conducted middle intensity treadmill exercise for 8 weeks.After exercise,the left anterior descending coronary artery was ligated for 30 min and then reperfused for 120 min to establish the I/R model.The values of left ventricular systolic pressure(LVSP),left ventricular end-diastolic pressure(LVDEP)and±dp/dtmax were measured by BL-420S biological function test system at pre-ischemia,ischemia 30 min and 120 min of reperfusion.Myocardial tissue was collected at 120 min after reperfusion,then the morphological changes in myocardial fiber were analyzed by HE staining,SOD activity in myocardial tissue was measured by xanthine oxidase assay,the MDA level in myocardial tissue was detected by thiobarbituric acid method and the protein expression of Drp1 and OPA1 in myocardial tissue of rats was detected by western blotting.Results:(1)Compared with the sham group,the myocardial tissue showed obvious pathological changes,LVSP and±dp/dtmax(P<0.01)significantly decreased,LVDEP(P<0.01)significantly increased;SOD activity(P<0.01)and the protein expression of OPA1(P<0.01)significantly decreased,MDA level(P<0.01)and protein expression of Drp1(P<0.01)significantly increased in myocardial tissue in the I/R group rats.(2)8-week treadmill exercise pre-intervention significantly improved the pathological changes in myocardial tissue and cardiac function in I/R rats,SOD activity(P<0.05)and the protein expression of OPA1(P<0.01)significantly increased,MDA level(P<0.01)and protein expression of Drp1(P<0.05)significantly decreased in myocardial tissue in the I/R+EX group rats when compared with I/R group.Conclusion:Exercise pre-intervention has a protective effect on myocardial ischemia-reperfusion injury,which may be related to the maintenance of the dynamic balance of mitochondrial division and fusion and the reduction of myocardial oxidative stress injury induced by I/R.