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目的:探讨缺血后处理(ischemic postconditioning,IPO)对大鼠肝脏一氧化氮合酶(nitric oxide sythase,NOS)表达的影响及意义。方法:建立70%大鼠肝脏缺血再灌注模型,将32只雄性SD大鼠随机分为3组:假手术组(SO组,n=8)、缺血再灌注组(IR组,n=12)、缺血后处理组(IPO组,n=12),IPO组于再灌注恢复血流前,给予多次短暂复灌复停处理。再灌注3h后,比较各组血清谷丙转氨酶(ALT)、谷草转氨酶(AST)变化,硝酸还原酶法测定一氧化氮(NO)含量,逆转录-聚合酶链反应法(RT-PCR)检测肝脏组织内皮型NOS(eNOS)mRNA、诱导型NOS(iNOS)mRNA表达,蛋白免疫印迹法(Western blot)检测肝脏组织eNOS、iNOS蛋白表达,光镜观察组织病理学改变。结果:与SO组相比,其余两组血清ALT、AST、NO含量均明显升高(P<0.01),组织eNOS、iNOS表达均明显增强。与IR组相比,IPO组ALT、AST明显降低(P<0.01),NO明显升高(P<0.01),eNOS、iNOS表达增强。光镜下,IR组、IPO组呈现典型缺血再灌注损伤的病理学改变,但IPO组损伤较IR组轻。结论:缺血后处理能明显减轻大鼠肝脏缺血再灌注损伤,其机制可能与增强缺血再灌注肝脏组织中eNOS表达、提高血清NO含量有关。
Objective: To investigate the effect of ischemic postconditioning (IPO) on the expression of nitric oxide synthase (NOS) in rat liver and its significance. Methods: A total of 32 male Sprague-Dawley rats were randomly divided into sham operation group (SO group, n = 8), ischemia reperfusion group (IR group, n = 12), ischemic postconditioning group (IPO group, n = 12). The IPO group was given repeated short-term reperfusion resuscitation before resumption of perfusion. After 3h of reperfusion, the levels of ALT and AST in serum were determined. The concentrations of nitric oxide (NO) were measured by nitrate reductase method. The levels of nitric oxide (NO) were detected by reverse transcription polymerase chain reaction (RT-PCR) The expression of eNOS mRNA and iNOS mRNA were detected by Western blotting. The expression of eNOS and iNOS protein in liver tissue were detected by light microscopy. The histopathological changes were observed by light microscopy. Results: Compared with the SO group, the levels of ALT, AST and NO in the other two groups were significantly increased (P <0.01), and the expression of eNOS and iNOS in the two groups were significantly increased. Compared with the IR group, the ALT, AST in the IPO group decreased significantly (P <0.01), the NO level increased (P <0.01) and the expression of eNOS and iNOS increased in the IPO group. Under the light microscope, IR group and IPO group showed the pathological changes of typical ischemia-reperfusion injury, but IPO group had less damage than IR group. Conclusion: Ischemic postconditioning can significantly reduce the hepatic ischemia-reperfusion injury in rats. The mechanism may be related to the enhancement of eNOS expression in liver tissue and the increase of serum NO level.