nNOS对小鼠心肌缺血再灌注损伤的影响

Effect of Neuronal Nitric Oxide Synthase on Myocardial Ischemia-reperfusion Injury in Mice

目的应用神经型一氧化氮合酶nNOS基因缺失小鼠,探讨nNOS对心肌缺血再灌注损伤的影响。方法野生型C57小鼠和nNOS基因缺失小鼠分别经过冠状动脉左前降支缺血30 min再灌注3 h,观察TUNEL染色和caspase-8,-9,-3的活性变化,并用Western blot法观察磷酸化p38激酶和胞外信号调节激酶(ERK)的表达情况。结果心肌缺血30 min再灌注3 h后,与假手术组相比,TUNEL阳性细胞数增加,caspase-8,-9,-3活性增强,差异有统计学意义(P<0.05)。野生组与基因缺失组相比,凋亡细胞数增多,caspase活性增强,差异具有统计学意义(P<0.05)。Western blot结果显示野生型小鼠缺血再灌注损伤后磷酸化p38和ERK激酶活性增强,而基因缺失组p38激酶活性降低,ERK活性不受影响。结论 nNOS具有加重心肌缺血再灌注损伤的作用,其作用可能为p38介导。

Objective To explore the effect of neuronal nitric oxide synthase（nNOS）on myocardial ischemia-reperfusion injury in mice.Methods In nNOS-/-（KO）mice and wild type C57（WT）mice,the left anterior descending coronary artery were ligated for 30 minutes,followed by 3-hour reperfusion.The cardiac myocyte apoptosis was detected by TUNEL staining,and the activities of caspase-3,-8,and-9and the expressions of phospho-p38 mitogen-activated protein kinase（MAPK）and extracellular signal-regulated kinase（ERK）were deter-mined by Western blot.Results Compared with control group,the number of TUNEL positive cells and the activities of caspase-3,-8,and -9 significantly increased after 30-minute ischemia followed by 3-hour reperfusion（P 0.05）.The number of TUNEL positive cells and the activities of caspase-3,-8,and-9 were significantly higher in WT mice than in KO mice（P 0.05）.After ischemia-reperfusion injury,the activities of phospho-p38 and ERK increased in WT mice,but in KO mice,the activity of phospo-p38 decreased and the activity of ERK was unchanged.Conclusion nNOS may exacerbate ischemia-reperfusion injury,in which p38 MAPK may be involved.