Protective effects of ischaemic postconditioning on warm/cold ischaemic reperfusion injury in rat liver: a comparative study with ischaemic preconditioning

Abstract

Ischaemic reperfusion injury (IRI) is inevitable during major liver surgery. Ischaemic preconditioning (IPC) has been proven an effective intervention against hepatic IRI. Recently, it was demonstrated that ischaemic postconditioning (IPO) provided effective cardioprotection on IRI. We evaluated the protective effects of IPO on warm/cold IRI in rat liver by a comparison with IPC and assessed the role of apoptosis in the process. Warm IRI model (clamping hepatic pedicle for 30 minutes) and cold IRI model (orthotopic liver transplantation with 2 hours cold storage) were established. Each model consisted of 3 groups: (1) control group, normal warm/cold IRI; (2) IPC group, 5 minutes of ischaemia followed by 5 minutes of reperfusion twice prior to warm/cold IRI; (3) IPO group, 30 seconds of reperfusion followed by 30 seconds of reocclusion for three times after warm/cold ischaemia. The levels of serum transaminase, glucose, and gamma glutamyltransferase (GGT) in bile, histopathological examination, apoptotic activity of hepatocyte, and apoptosis related protein Fas, at 3 hours after operation were compared. Survival rates one week after intervention were also compared. IPO and IPC protected the functions of hepatocytes and biliary epithelial cells, inhibited the hepatocellular apoptosis by preventing expression of Fas gene, and elevated the one week survival rate compared with control group in both models (P < 0.05). IPO and IPC groups were comparable in levels of serum transaminase levels, glucose, and GGT in bile, Fas positive expression index, and one week survival. In cold ischaemic models, IPO had lower apoptotic index than IPC (P < 0.05). Compared with ischaemic preconditioning, ischaemic postconditioning is associated with comparable protections of rat liver from warm or cold ischaemic reperfusion injury.