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Objective:Study the role of cyclooxygenase-2（Cox-2）and PGI2/TXA2 on ischemia-reperfusion injury after liver transplantation in rat,and to investigate possible mechanisms.Method:Rats were randomly divided into three groups:control group（E1）,liver IR group（E2）,NIM and liver IR group（E3）,orthotropic liver transplantation group（E4）,NIM and orthotropic liver transplantation group（E5）.Cold preservation group（E6）;To obtain the samples 3h,6h,12h,24h post operation or portal vein opened and obtain the samples 1h/3h after cold preservation;Alanine aminotransferase（ALT）and Aspartate aminotransferase（AST）was measured; Radio-immunity assay was used to detect 6-Keto-PGF-1a,TXB2（stable metabolites of the TXA2 and PGI2）in tissue and plasma in every group;Two step-RT-PCR and Immunohistochemistry were used to detect the expressions of Cox-2 and location; Hematoxylin Eosin staining was used to classify the injury extent of every samples, Enzyme linked immunosorbent assay ELISA was used to detect the value of TNF-a in E6 group.Result:1.The expressions of Cox-2 and the value of 6-Keto-PGF-1a,TXB2 in E2,E3,E4, E5,E6 group were significantly higher than in the E1 group（P＜0.05）, especially the TXB2,ratio of TXB2 / 6-Keto-PGF-1a was increment in E2 E4 and E6;The dates of the E3 and E5 were significantly lower than the E2 and E4 group（P＜0.05）,TXB2 was reduced obviously,and the ratio of TXB2/ 6-Keto-PGF-1a was diminution;2.Immunohistochemistry examination showed that injury of liver injury was significantly lightened in E3 and E5 group compared with the E2 and E4 group; Cox-2 was degraded in Cox-2 inhibitor preconditioning both in E3 and E5 groups. 3.In E6 group,the TXB2 / 6-Keto-PGF-1a and TNF-a were significantly higher than E1 group after 1h/3h cold preservation.But our dates did not have statistical significance between 1h and 3h.4.The level ofAST,ALT in blood serum,the date of E2,E3,E4,E5 was significant hingh compared with E1（P＜0.05）E2 and E4 was significant hingh compared with E3 and E5 groups,E4 group was significant hingher than E2 group（P＜0.05）;Conclusion:Our dates showed that Cox-2 has harmful effects in I/R injury in liver-transplantation and Cox-2 inhibitor may protect the liver.The mechanism was partly reduction of TXB2 and regulating balance of TXA2/PGI2.TXA2/PGI2 and TNF-a may have important effects in liver cold preservation injurys.
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