缺血后处理对大鼠肠缺血再灌注保护作用及机制

Protective effect of ischemic postconditioning on intestinal ischemia-reperfusion injury and its mechanism

目的观察肠缺血后处理（I—post C）对缺血再灌注（in）损伤的保护作用，探讨I—postC在肠IR损伤中的作用机制。方法 雄性SD大鼠72只，随机分为假手术组（S组），缺血再灌注组（IR组）和缺血后处理组（I—post C组），每组再分为再灌注10min、45min及90min三亚组，测定血浆及肠组织二氨氧化酶（DAO）活性、超氧化物歧化酶（SOD）活性、丙二醛（MDA）浓度、髓过氧化酶（MPO）含量、诱导型一氧化氮合成酶（iNOS）mRNA表达量，以及血浆一氧化氮（NO）浓度（以NO2^-／NO3^-代表）。结果（1）与IR组比较，I—postC组肠组织DAO在45min和90min显著升高（P〈0．05），血浆DAO在45min和90min显著减低（P〈0．05）；（2）与IR组比较，I—postC组在10、45和90min降低肠组织MDA与MPO含量（P〈0．05），在45min与90min显著升高肠组织SOD活性（P〈0．05）；（3）I—postC组血浆NO含量及iNOSmRNA表达在45min和90min均明显高于IR组（P〈0．05）。结论肠IR损伤与iNOS过高表达及NO大量产生有关。I—postC对肠IR损伤的拮抗作用可能与I—postC诱导早期产生低水平NO，发挥其信号保护效应相关。

Objective To study the protective effects of intestinal ischemic postconditioning （I -postC） on ischemia- reperfusion （IR） injury and its mechanism. Methods Seventy - two Spraque - Dawley rats were divided into three groups at random ： control group,IR group and I - postC group. Each group was subdivided into 10, 45 and 90min reperfusion subgroups （ n = 8）. The activity of diamide oxidase （DAO） was measured by spectrophotometry. The activity of superoxide dismutase （SOD） was measured by xanthine oxidase method. The content of maleic dialdehyde （MDA） was measured by thiobarbituric acid chromatometry. The content of myeloperoxidase （MPO） was measured by myeloperoxidase method. The content of nitric oxide （NO） was measured with nitrate reductase method. The expression of nitric oxide synthase （iNOS） in intestine were detected by real - time quantitative PCR（ RT - PCR）. Results （ 1 ） Compared with IR group, DAO in the intestinal tissue markedly increased （P 〈 0.05） and DAO in the plasma significantly decreased at 45 min and 90 min after reperfusion in I - postC group（P 〈0.05）. （2） Compared with IR group, MDA and MPO in the intestinal tissue significantly decreased at 10,45 and 90 min after reperfusion in I - postC group（P 〈 0.05 ）, and intestinal SOD activity markedly increased at 45 min and 90 min in I - postC group （P 〈 0.05）. （3） Compared with IR group, I - postC significantly lowered the levels of NO in the plasma and iNOS mRNA expression at 45min and 90min （P 〈 0.05 ）, while level of NO in the plasma in IR group was higher than in I - postC group at 10min after reperfusion （ P 〈 0.05）. Conclusions The intestinal injury following IR is related to the disturbance of NO and elevated expression of iNOS. The protecting effects of I - postC might be induced by earlier but lower NO levels and it＇ s protective effects.