Phosphorus 31-nuclear magnetic resonance spectroscopy of rat liver during simple storage or continuous hypothermic perfusion

The adenosine triphosphate (ATP) content and intracellular pH (pH₁) of isolated rat liver before, during, and after cold preservation in either University of Wisconsin lactobionate solution (UW) (n = 10) or Euro-Collins solution (EC), (n = 8) were monitored with phosphorus 31 nuclear magnetic resonance. The ³¹P nuclear magnetic resonance spectra were obtained on a 4.7 T system operating at 81 MHz. Fructose metabolism, liver enzyme release, oxygen consumption, and rat survival after liver transplantation were also evaluated. During simple cold storage (SCS) the ATP level declined to undetectable levels with both preservation solutions whereas the pH₁ declined to approximately 7.0. In contrast, during continuous hypothermic perfusion (CHP), hepatic ATP levels remained measurable during the 24-hour EC preservation and actually increased significantly (p > 0.01) during UW preservation. After reperfusion at 37 °C with Krebs lactate, the livers in SCS treated with EC differed significantly from the UW-treated livers in terms of their ATP level and pH₁ and their response to a fructose challenge. In contrast, livers undergoing CHP demonstrated similar behaviors with both solutions. These results demonstrate an increase in the hepatic ATP content during CHP, which occurs with UW but is not seen with EC. On the other hand, only livers that were simply stored with UW achieved significant survival after transplantation, whereas CHP livers were affected by vascular damage as demonstrated by fatal thrombosis after transplantation. These data suggest that ATP content is not the only determinant of good liver function. A system of hypothermic perfusion might further improve liver preservation efficacy should injury to the vascular endothelium be avoided.