Ischemic preconditioning in a rodent hepatocyte model of liver hypothermic preservation injury

Ischemic preconditioning (IPC) is a phenomenon of protection in various tissues from normothermic ischemic injury by previous exposure to short cycles of ischemia–reperfusion. The ability of IPC to protect hepatocytes from a model of hypothermic transplant preservation injury was tested in this study. Rat hepatocytes were subjected to 30 min of warm ischemia (37 °C) followed by 24 or 48 h of hypothermic (4 °C) storage in UW solution and subsequent re-oxygenation at normothermia for 1 h. Studies were performed with untreated control cells and cells treated with IPC (10 min anoxia followed by 10 min re-oxygenation, 1 cycle). Hepatocytes exposed to IPC prior to warm ischemia released significantly less LDH and had higher ATP concentrations, relative to untreated ischemic hepatocytes. IPC significantly reduced LDH release after 24 h of cold storage before reperfusion and after 48 h of cold storage and after 60 min of warm re-oxygenation, relative to the corresponding untreated hepatocytes. ATP levels were also significantly higher when IPC was used prior to the warm and cold ischemia-re-oxygenation protocols. In parallel studies, IPC increased new protein synthesis and lactate after cold storage and reperfusion compared to untreated cells but no differences in the patterns of protein banding were detected on electrophoresis between the groups. In conclusion, IPC significantly improves hepatocyte viability and energy metabolism in a model of hypothermic preservation injury preceded by normothermic ischemia. These protective effects on viability may be related to enhanced protein and ATP synthesis at reperfusion.