Isolated perfusion of rat livers: effect of temperature on O2 consumption, enzyme release, energy store, and morphology.

The effect of temperature on isolated rat liver perfusion was studied. Livers were perfused for 12 hours with oxygenated Krebs-Henseleit solution at 5, 10, 15, 20, 25 and 30 degrees C, followed by one hour normothermic reperfusion. After each perfusion, oxygen consumption, liver enzyme release, tissue swelling, energy metabolism and histopathological abnormalities were determined. Compared to the oxygen consumption at 37 degrees C, that of 25, 10 and 5 degrees C was 47%, 16% and 12%, respectively. When the liver was perfused at 30 degrees C, higher enzyme release and lower energy status was observed. Tissue swelling was significant only with livers perfused at 5, 10 and 30 degrees C. After normothermic reperfusion, liver injury indicated by enzyme release and bile production was remarkable with 30 degrees C liver, and that of the other groups was essentially the same as the control. ATP of 5, 25 and 30 degrees C liver was significantly lower than the control. Histopathological examination demonstrated abnormalities of sinusoidal cells and hepatocytes in livers perfused at 25 degrees C and 30 degrees C Thus higher temperature (25 degrees C to 30 degrees C) during continuous perfusion were found to induce liver damage. Moderate hypothermia between 10 degrees C and 20 degrees C maintained structure and function of rat livers rather well. These results suggest that, when a machine perfusion of the liver is attempted, a wider temperature range, higher than the conventional, needs to be taken into consideration.