[Prolongation of ischemic tolerance time of donor livers by alkaline preservation solutions]

Intracellular enzyme activities can be greatly influenced by alterations of pH, and non-physiologic pH may inhibit cell metabolism. The study was undertaken to examine the influence of pH values in preservation solution on ischemic tolerance time of the liver. BDE rat livers were used. Livers were preserved for 20 min or 2 h in warm ischemia after an initial perfusion with Ringer's solution at pH 9.0, 7.4, and 6.0. The values of total adenine nucleotide (TAN) and energy reserve (ER) in the livers were determined at the end of the preservation. After 20 min of warm ischemia, TAN values at pH 9.0 and 7.4 fell to 2.727 +/- 0.255 and 2.410 +/- 0.164 mumol/g, respectively (normal values: 3.414 +/- 0.270 mumol/g) and ER values to 0.786 +/- 0.186 mumol/g at pH 9.0 and to 0.446 +/- 0.095 mumol/g at pH 7.4 (normal values: 2.962 +/- 0.214 mumol/g). A similar trend was also observed after 2 h of warm ischemia. The preservation with a solution at pH 6.0 did not present any difference as compared to that at pH 7.4. Four-hour preservation in cold ischemia with Ringer's solution at pH 9.0 rendered higher values of TAN (2.635 +/- 0.085 mumol/g) and ER (0.336 +/- 0.026 mumol/g) than those in preservation at pH 7.4. No significant difference between TAN and ER values was found when 4-h preservation at pH 7.4 and 6.0 was compared. In another group an intermittent liver perfusion at 1-h interval was performed with chilled Ringer's solution; afterwards GOT, GPT, beta-glucuronidase, and acid phosphatase values in the effluents were evaluated. All of these enzymes showed higher concentration in the effluent with solution at pH 7.4 than that at 9.0. These results suggested that better intracellular energy reserve and organ viability can be maintained by preservation with alkaline solution. Furthermore, ER values seemed to be an excellent indicator of the organ viability during preservation. These were also confirmed by orthotopic hepatic transplantation in pigs. Livers were successfully preserved with alkaline Ringer's solution for up to 12 h. However, without change of pH, livers could not be preserved for more than 4.5 h.