| Objective Intestinal ischemia reperfusion injury is one of the tissue injury in surgery clinical practice, it has not yet been clarified about the exact pathophysiology mechanism of ischemia-reperfusion injury (IRI), this is associated with the complex pathway which caused by multiple factors. P-selectin protein and mRNA, ICAM-1 expression were determined by immunohistochemistry and RT-PCR technique respectively in rats intestinal I/R . Meantime alteration myeloperoxidase (MPO) and diamine oxidase (DAO) levels were assayed. N-acetylcysteine (NAC) was used to evaluate the potential therapeutic value in intestinal I/R injury. The purpose of this study was not only to explore the relationships between expression of P-selectin or ICAM-1 and intestinal injury, but also to find an exact pathophysiology mechanism of ischemia reperfusion injury.Methods 48 Male inbred Sprague-Dawley (SD) rats were divided into eight groups ( 6 rats in each group): G1 was sham group; G2-G4 were I/R groups with different reperfusion time; G5-G8 were treatment groups with NAC; Drugs were administered intravenously via femoral vein after I/R with different time . (NAC applied at 150mg/Kg). The concrete groups and process as following: Groupl: sham group; Group2:1 40min/ R30min; Group3: I 40min/ R 60min; Group4: I 40min/ R240min; Group5: I40min/R30min (applied NAC prior to ischemia); Group6: I 40min/R30min (applied NAC reperfusion simultaneously); Group7: I 40min/ R60min (applied NAC after reperfusion 30min); Group8: I 40min/ R240min (applied NAC after reperfusion 120min). Each group P-selectin protein and Ps-mRNA expression, ICAM-1 molecule were assayed, respective alteration in myeloperoxidase (MPO), diamine oxidase(DAO) levels in blood and tissues were assayed to reflect the neutrophil congregation and intestinal injury degree. Tissue lesions and histopathological changes were determined by the light and electron microscope.Results 1. The level of Ps mRNA in the intestine: It was very low in sham group. After I 40/R30min Ps mRNA expression showed significant up-regulation (p<0.05), but it was became low by used NAC at 0 or 30 minutes reperfiision.2. The level of P-selectin in the intestine: It was very low or not expression in sham group. After I/R P-selectin expression showed respectively up-regulation, the peak values was found in the I 40/ R60min group (p<0.01), but it was became low by used NAC at forepart reperfusion.3. The level of ICAM-1 in the intestine: It was very low or not expression in sham group. It was obviously increased in I 40/ R30min group and the peak values was found in the I 40/ R240min group. The level of ICAM-1 was became low by used NAC after 0 or 30 minutes reperfusion, but it was not evidently altered by used NAC at 120 minutes reperfusion.4. Myeloperoxidase (MPO) activity in blood and in the intestine: It was very low in sham group, MPO activity were respectively showed obvious elevation in the groups after intestinal I/R (p<0.01), but it was evidently declined by used NAC at 0 or 30 minutes reperfusion. Myeloperoxidase (MPO) activity in blood and degrees of intestinal injury were positive correlation(r=0.619, p<0.01), the neutrophil congregation and intestinal injury degree had an evident relationship.5. Diamine oxidase (DAO) activity in blood and in the intestine: The level of DAO inblood in I/R groups were highter than in shamp group (p<0.01), but the level of DAO in intestinal were low (p<0.01). The peak values in blood and nadir values in intestinal were found in the I40/R60min. Diamine oxidase activity in the blood was evidently depressed by used NAC at 0 or 30 minutes reperfusion. Diamine oxidase activity in blood and degree of intestinal injury were positive correlation(r=0.92, p<0.05), The more diamine oxidase activity was high, the more degree of intestinal injury was serious.6. Histopathology change and injury grade in intestine: The intestinal tissue respectively injury were found in I/R groups using microscope, the serious intestinal tissue injury were found in I40/R60mi...
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