Effects of different cold preservation solutions on restoration of hepatic energy metabolism during cold reperfusion.

Rat livers were flushed with different preservation solutions and stored at 4 degrees C for 24 h before being reperfused with a synthetic air-equilibrated, water-based solution. Four solutions were tested using this isolated rat liver model: Marshall's hypertonic citrate (HC); modified University of Wisconsin solution (Mod UW); a histidine-based solution (HIS); and a histidine-lactobionate-raffinose-based solution (HLR). After storage, livers were perfused at 4 degrees C for a period of 2 h and biopsy samples taken, at different time points, to investigate energy metabolism. Livers stored in HLR and HIS had higher 24-h storage levels of ATP (0.41 and 0.24 mumol/g respectively; P < 0.05) than those stored in Mod UW and HC. On reperfusion, all groups regenerated ATP by 1-2 h. However, significantly greater levels of ATP regeneration occurred in livers stored in the HLR (1.6 +/- 0.08 mumol/g) and Mod UW (1.3 +/- 0.18) than HC (0.58 +/- 0.19) and HIS (0.96 +/- 0.12); P < 0.05. Energy charge (1) (EC) recovered in all groups but was significantly higher in HLR and Mod UW (0.79 and 0.68, respectively; P < 0.05) than HC and HIS. These represent 95% (HLR) and 80% (Mod UW) of values observed in FIL. During the reperfusion period, total adenine nucleotide levels (TA) did not vary significantly within each storage group, except in the HIS solution. However, TAs were greater with livers stored for 24 h in HLR (2.5 +/- 0.25) and Mod UW (2.7 +/- 0.20) than those the other two storage groups (P < 0.05 in each case). This study has demonstrated that it was possible to resuscitate liver energetics after prolonged hypothermic ischemia by a period of cold reperfusion, and the method can differentiate between preservation solutions. The livers stored in each solution showed varying degrees of success in regeneration of ATP and EC, demonstrating that oxygen was not a limiting factor when using an air-equilibrated perfusate. The solutions providing the better preservation conditions gave the greater resuscitation of liver energetics (Mod UW and HLR). Overall, livers stored in HLR had the greatest resuscitation of energy metabolism, which correlates with survival data from other studies (29-31, 33).