Difference in energy metabolism between fresh and warm ischemic canine pancreases during preservation by the two-layer method.

Abstract

We have demonstrated that adenosine triphosphate (ATP) is synthesized within a canine pancreas during preservation by the two-layer method and there is a direct correlation between a high ATP tissue level and good posttransplant outcome. The purpose of this study was to examine the difference in energy metabolism between fresh and warm ischemic pancreases during preservation by this method. First, fresh pancreases were preserved with simple cold storage in Euro-Collins solution (EC; group 1A), or by the two-layer method using EC (group 1B), EC with 2,4 dinitrophenol (DNP; group 1C), an uncoupler of oxidative phosphorylation, or modified EC (ECM; group 1d), which contained mannitol in place of glucose for 48 h. ATP tissue concentrations in group 1B were significantly higher than in group 1A (7.91 +/- 1.21 vs. 1.21 +/- 0.31 micromol/g dry weight, P < 0.01) but almost equal to group 1d (7.91 +/- 1.21 vs. 7.59 +/- 0.97 micromol/g dry weight, NS). DNP (group 1C) caused a significant decrease in tissue ATP levels in group 1A (0.61 +/- 0.07 vs. 7.91 +/- 1.21 micromol/g dry weight, P < 0.01). Second, pancreases subjected to 60 min of warm ischemia were preserved by simple cold storage with EC (group 2A) or the two-layer method using EC (group 2B) or EC with adenosine (group 2C) for 24 h. ATP tissue levels in groups 2A and 2B after preservation were 1.40 +/- 0.46 and 1.56 +/- 0.40 micromol/g dry weight and graft survival rates were 0/5 (0%) and 0/3 (0%), respectively. However, tissue ATP levels in group 2C after preservation were significantly higher compared with the value before preservation (7.23 +/- 2.17 vs. 1.90 +/- 0.53/g dry weight, P < 0.01) and graft survival rate was 4/5, 80%. Other nucleosides, hypoxanthine, inosine, and adenine did not substitute for adenosine. In addition, studies with [2-3 H] adenosine demonstrated that almost all of the adenosine was converted to adenine nucleotides. This study clearly demonstrated that fresh grafts synthesize ATP mainly via mitochondrial oxidative phosphorylation using endogenous substrates. However, after significant warm ischemia, pancreases produce ATP mainly via direct phosphorylation of exogenous adenosine during preservation by the two-layer method.