| Objective:To investigate the protective effects of ischemic postconditioning on isolated lung of ischemic reperfusion injury in rats and analyse its possible mechanisms.Methods:18 rats were randomly allocated to three groups(n=6 each group).The models of ischemia-reperfusion injury in isolated buffer-perfused rat lungs were prepared.①control group:isolated lungs were interrupted perfusion for 2 hours and followed by reperfusion for 1 hour.②preconditioning group:before ischemia, isolated lungs were interrupted perfusion for 5 minutes and perfused for 5 minutes (5I/5R),then the protocol was repeated one time.The other procedure was identical to control group.③postconditioning group:at the end of ischemia,isolated lungs were perfused for 5 minutes and interrupted perfusion for 5 minutes(5R/5I),then the protocol was repeated one time.The other procedure was identical to control group.Pulmonary arterial pressure was measured continuously.Pulmonary arterial pressure was recorded before ischemia,at the end of ischemia and the end of reperfusion,respectively.3ml perfusate was obtained before ischemia and at the end of reperfusion.A small piece of lung tissue(about 20mg) was cut before ischemia,at the beginning of reperfusion and end of reperfusion for preparation of homogenate.The concentration of interleukin-8, interleukin-10,malondialdehyde and glutathione in perfusate and homogenate were determined.The wet to dry weight ratio was also measured at the end of reperfusion. Results:Compared with preischemia,pulmonary arterial pressures in three groups all increased significantly at the end of ischemia(P＜0.05).Compared with the end of ischemia,pulmonary arterial pressures in three groups all decreased significantly at the end of reperfusion(P＜0.05).There was no significant difference among three groups at the end of reperfusion in the pulmonary arterial pressures(P＞0.05).But the levels of IL-8 of lung and perfusate in postconditioning group and preconditioning group all decreased significantly at the end of reperfusion comparied with the control group(P＜0.05).The levels of IL-10 of lung and perfusate in postconditioning group and preconditioning group all increased significantly at the end of reperfusion comparied with the control group(P＜0.05).The levels of MDA of lung and perfusate in postconditioning group and preconditioning group all decreased significantly at the end of reperfusion comparied with the control group(P＜0.05).There was no significant difference among three groups at the end of reperfusion in the levels of GSH of lung and perfusate(P＞0.05).The W/D of lung in postconditioning group and preconditioning group all decreased significantly at the end of reperfusion comparied with the control group(P＜0.05).Conclusion: Ischemic postconditioning can reduce significantly ischemia-reperfusion injury in isolated lung of rats.The possible mechanism is that postconditioning may decrease levels of IL-8 and MDA,increase level of IL-10 and alleviate pulmonary edema. |
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