The role of ischemic preconditioning in rat liver graft

OBJECTIVE: The objective of this study was to investigate the protective effects of different modes of ischemic preconditioning (IPC) on an ischemia/reperfusion (I/R) injury in rat liver graft. METHODS: A total of 192 Wistar rats were randomly allocated into 4 groups, each including 48 rats: control group (C), experimental group 1 (E(1)), experimental group 2 (E(2)), and experimental group 3 (E(3)). IPC was not performed in group C. Among the animals in the experimental groups, IPC was performed by blocking blood flow by the portal vein and the hepatic artery followed by reperfusion by removal of the clamp before donor liver resection: Group E(1), 5-minute ischemia and 10-minute reperfusion; Group E(2), 5-minute ischemia and 5-minute reperfusion and immediately the same procedure; and Group E(3), 10-minute ischemia and 15-minute reperfusion. Liver transplantations were performed 4 hours after IPC. At 0.5 hour, 2 hours, 6 hours, and 24 hours after portal vein reperfusion recipient blood and graft samples were obtained to determine the levels of ALT, AST, TNF-alpha, and apoptosis index (AI). RESULTS: At 0.5 hour and 2 hours after portal vein reperfusion, serum tumor necrosis factor (TNF)-alpha in the experimental groups (E(1), E(2), and E(3)) was significantly lower than in the control group (P < .05). The values in group E(2) were significantly lower than those in groups E(1) and E(3) (P < .05). At 24 hours serum TNF-alpha in group E(2) was significantly lower than groups C, E(1), and E(3) (P < .05). At 2 hours and 6 hours, AI values in experimental groups (E(1), E(2), and E(3)) were significantly lower than in group C (P < .05). AI in group E(2) was significantly lower than that in groups E(1) and E(3) (P < .05). At 24 hours, AI values among experimental groups (E(1), E(2), and E(3)) were significantly lower than that in the control group (P < .05). CONCLUSION: IPC may attenuate liver graft injury by decreasing apoptosis of hepatocytes and production of TNF-alpha. The method of IPC with 5-minute ischemia and 5-minute reperfusion followed immediately by another cycle of the same procedure was a better way to protect a liver graft from I/R injury.