gamma-Hydroxybutyrate mediated protection of liver function after long-term hypothermic storage

Liver function was measured after 20 hr of hypothermic preservation in University of Wisconsin (UW) solution and in modified UW (MUW) solution containing gamma-hydroxybutyrate (GHB). Rat livers were rapidly cooled by in situ portal flushing with chilled UW or MUW solution, then removed and stored at 4 degrees C. After 20 hr of storage, liver hemodynamics and function were studied during 90 min of reperfusion in an isolated perfused liver system. Three groups were investigated: livers flushed with and stored in a commercial UW solution for 20 hr (UW group) or in a modified UW solution with 500 mg/L of GHB added (MUW group), and livers flushed with UW solution and reperfused immediately thereafter (control group). Addition of GHB to the cold storage solution significantly improved liver function after 20 hr of cold storage. Livers in the MUW group produced bile at a much higher rate then those in UW group (3.47 +/- 0.34 vs. 0.87 +/- 0.29 ml/100 g liver weight/min at 60 min of reperfusion), while the control livers produced 4.60 +/- 0.40 ml bile/100 g liver weight/min. At the same time, liver blood flow at a perfusion pressure of 11 cm H2O was significantly higher in the MUW group than in the UW group (391 +/- 32 ml/min/100 g liver vs. 177 +/- 33 ml/min/100 g liver) and only slightly lower than in the control group (494 +/- 49 ml/min/100 g liver). Aspartate amino-transferase (AST) and alanine aminotransferase (ALT) levels in perfusate samples taken from the venous effluent were raised during reperfusion in all groups. However, AST and ALT values were significantly lower (503 +/- 88 IU/L/100 g AST, 184 +/- 33 IU/L/100 g ALT) at 90 min of reperfusion in the MUW group than in the UW group (1567 +/- 330 IU/L/100 g for AST and 644 +/- 227 IU/L/100 g for ALT). This study clearly demonstrates that GHB greatly improves liver function and integrity after hypothermic preservation and has the potential to substantially increase the acceptable storage time of donor livers before transplantation.