The significance of tissue-type plasminogen activator for pretransplant assessment of liver graft viability: analysis of effluent from the graft in rats

We studied the significance of tissue-type plasminogen activator (tPA) on the pretransplant assessment of liver graft viability in rats. The liver grafts were excised from the rats and then divided into two groups. Group 1 consisted of grafts preserved for 4 h in chilled, lactated Ringer's solution (4°C) and group 2 consisted of grafts preserved for 6 h in the same solution. After preservation, the liver grafts were flushed out through the portal vein using 5 ml of chilled, lactated Ringer's solution (4°C). The entire effluent from the hepatic veins was then collected and analyzed for tPA, ammonia, lactate, pyruvate, glutamic oxaloacetic transaminase, and lactate dehydrogenase. The tPA concentration of effluent in group 2 was significantly higher than that in group 1 (0.80±0.23 ng/ml vs 0.42±0.08 ng/ml, P<0.05). The lactate, pyruvate, and ammonia levels in group 2 were also higher than those in group 1 (134±13 mg/dl vs 120±2 mg/dl, 0.34±0.40 mg/dl vs 0.09±0.01 mg/dl, and 183±79 μg/dl vs 102±40 μg/dl, respectively). However, the discriminative power of tPA was stronger than that of the other parameters. Histological findings revealed a higher number of trypan blue-stained sinusoidal lining cells that were detached and swollen in group 2. We conclude that the amount of tPA in the effluent flushed from the graft can serve as a sensitive and reliable indicator of cold-preserved liver grafts in rats.