肢体缺血预适应的肝保护作用与一氧化氮/内皮素-1系统关系的研究

The protective effect of the limb ischemia preconditioning on the hepatic injury related to NO/ET-1 system in rats

目的:观察肢体缺血/再灌注(I/R)后一氧化氮/内皮素-I(NO/ET-1)失衡与肝损伤的关系以及缺血预适应(IPC)对NO/ET-1系统的调节作用。方法:实验用雄性Wistar大鼠18只,随机分为3组(n=6):对照组(control)、缺血/再灌注组(I/R)和缺血预适应组(IPC+I/R),分别测定血浆谷草转氨酶(ALT)、谷丙转氨酶(AST);血浆和肝组织一氧化氮(NO)、内皮素-1(ET-I)的含量变化,一氧化氮/内皮素-1(NO/ET-1)比值及肝组织的总一氧化氮合酶(tNOS)、诱导型一氧化氮合酶(iNOS)、结构型一氧化氮合酶(cNOS)的水平;免疫组化法检测肝组织的诱导型一氧化氮合酶(iNOS)、内皮型一氧化氮合酶(eNOS)的表达;HE染色,在光学显微镜下观察肝组织的形态学改变。结果:发现肢体再灌注期血浆和肝组织NO、ET-1均明显增加,而NO/ET-1的比值却明显降低,同时血浆ALT、AST升高,光学显微镜下肝细胞、内皮细胞肿胀,肝细胞变性及肝窦淤血,炎性细胞浸润,肝损伤加重,肢体I/R后肝组织iNOS的表达增强,而cNOS(主要为eNOS)的表达减少,伴有总NOS活性增强。说明肢体缺血再灌注后肝组织内皮源的NO产生减少,而非内皮源的NO产生增多;IPC减轻了肢体I/R后引起的NO/ET-1失衡。结论:肢体I/R后肝组织损伤与NO/ET-1失衡有关,IPC对肢体I/R继发的肝组织损伤的保护作用可能是通过对NO/ET-1系统的调节作用而介导的,此时内皮源的NO产生增加,非内皮源的NO产生减少。

Objective： To study the relationship between the disiurhance of nitric oxide/endothelin-1 （NO/ET-1） and the hepatic injury following limb ischemia/repeffusion （I/R） in rats as well as the regulation of NO/ET-1 system by limb ischemia preconditioning （IPC）. Methods： Using limb ischemia/repeffusion injury model rats, animals were randomly divided into three groups （ n = 6） ： control group, I/R group and IPC group. The contents of alanine aminotransferase （ALT） ,aspartate aminotransferase （AST） in the plasma as well as nitric oxide （NO）, endothelin-1 （ET-1 ）, nitric oxide/endothelin-1 （NO/ET-1 ） in the plasma and the liver were measured. The levels of total nitric oxide synthasase （tNOS）, inducible nitric oxide synthasase （iNOS）, corrostitutive nitric oxide synthasase （cNOS） in the liver were determined. The expression of iNOS and endothelial NOS （eNOS） were detected by the immunohistochemical method. The morphologic changes stained with hematoxylineosin were observed under microscope. Results： It was found that the levels of NO, ET-1 in the plasma and the liver tissue all increased after reperfusion, while the values of ALT, AST, NO/ET-1 decreased. Liver pathology revealed that after limb I/R there were edema, villous microvascular congestion, infiltration of polymorphonuclear nutrophil （PMN）, cell degeneration in part cells of the liver. The hepatic damage was deteriorated. While the expression of iNOS elevated, cNOS （mainly eNOS） reduced and total NOS increased. The protection of the limb IPC attenuated the disturbance of NO/ET-1. Conclusion： The hepatic injury following limb I/R is related to the disturbance of NO/ ET-1. The protection of the limb IPC might be conducted by its regulation of NO/ET-1 system. The elevation of endothelial NOS and the reduction of non-endothelial NOS generated the NO in this situation.