<Original Articles>Isolated Perfusion of Rat Livers : Effect of Temperature on O2 Consumption, Enzyme Release, Energy Store, and Morphology

Abstract

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°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°C, that of 25, 10 and 5°C was 47%, 16% and 12%, respectively. When the liver was perfused at 30°C, higher enzyme release and lower energy status was observed. Tissue swelling was significant only with livers perfused at 5, 10 and 30°C. After normothermic reperfusion, liver injury indicated by enzyme release and bile production was remarkable with 30°C livers, and that of the other groups was essentially the same as the control. ATP of 5, 25 and 30°C livers was significantly lower than the control. Histopathological examination demonstrated abnormalities of sinusoidal cells and hepatocytes in livers perfused at 25°C and 30°C. Thus higher temperature (25°C to 30°C) during continuous perfusion were found to induce liver damage. Moderate hypothermia between 10°C and 20°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.

移植の為の肝臓保存には保存時聞の延長と共に今後の展開として障害肝の Viability の向上, 抗原性修飾が求められており, このためには現在臨床で用いられている Simple cold storage 法にかわって代謝を維持しつつ保存しうる肝灌保存法の開発が必須である. 肝の代謝は温度に強く影響されるため, ラット肝を用いて, 肝灌保存法における至適温度の研究を行った. Krebs-Henseleit 液を用いて5-30度で12時間灌流後, 37度で1時間再灌流を行い, 酸素消費, 胆汁産生量, 組織内水分, 電解質, Adenine nucleotide 量, 灌流液中肝逸脱酵素量, 組織所見を用いて, 評価した. 30度郡において, 再灌流後, 胆汁産生量 0. 44±0. 10 ml/h, 組織 K/Na 比 0. 90±0. 23 Total adenine 量 2. 89±0. 35 μmol/g, Total adenine 量 2. 89±0. 35 μmol/g, ATP 量 1. 19±0. 34 μmol/g, Total adenine 量 2. 89±0. 35 μmol/g, Energy Charge 0. 55±0. 06 と有意に低下し, 灌流液中 AST 量 136±22 IU/L, LDH 量 566±136 IU/L と有意の上昇を示した. 25度群では ATP 1. 92±0. 38 μmol/g, Total adenine 量 3. 97±0. 53 μmol/g, 組織 K/Na 比 1. 27±0. 13 と有意に低値を示した. 再灌流後の組織所見でも25度群および30度群で, 類洞細胞, 肝細胞の著明な変化が認められた. 5度群では低温灌流時に細胞内カリウムの流出, 水分の取り込みがみられたが, 復温時にこれらの異常は是正された. 10 - 20度では胆汁産生量, 組織 K/Na 比, Adenine nucleotide profile, 灌流液中肝逸脱酵素量, および組織所見にコントロールと差はなく, 目的に応じて, 20度まで温度範囲をひろげて, 新しい灌流条件の確立を目指すことが可能と考えられた.