To determine the viability of livers after transplantation, three groups of experimental models were prepared (i. e., liver transplantation by the modified Starzl method ; hepatic cold-ischemia with cold ischemic time equal to transplantation time ; and simple laparotomy with sugar loading). Changes in plasma-free amino acid levels were investigated.
The results showed an elevation of total amino acid levels in the early stage of a viable liver transplant. In addition, a decrease in the molar ratio of branched chain amino acids and aromatic amino acids was observed during the rejection period. The results also confirmed an increase in ornithine level, NH3, and ornithine carbamyl transferase as well as a decrease in the citrulline level, and unchanged arginine. A disturbance in the reaction in the urea cycle during the second stage was considered the cause. Among the plasma amino acids, alanine showed the greatest increase during the rejection period. This might be attributed to an acceleration in alanine release in the periphery, and an abnormal glucose-alanime cycle.
As described above, examining changes in plasma-free amino acid levels may be an effective index of the viability of a liver transplant, both in the early stage and during the rejection poriod.