Effect of hyperthermia on isolated perfused rat liver

Four groups of isolated rat liver underwent perfusion at 37°C for 1 h, at 37, 40, 43 or 45°C, respectively, during the 2nd hour and then at 37°C again for the 3rd hour. Vascular resistance slightly decreased during hyperthermia and then significantly increased after restarting normothermic perfusion. At 40°C bile production, oxygen consumption, glucose and lactate release did not significantly differ from those found in the 37°C group. At 43 and 45°C all these parameters were significantly impaired when compared to the 37 and 40°C groups and did not recover after normothermic perfusion was restored. GOT and GPT release increased in proportion to the temperature. Microscopic examination revealed normal histologic features in 37 and 40°C specimens while alterations such as vacuolization and focal necrosis were found in the 43 and 45°C groups. These data indicate that the highest temperature that is well tolerated by isolated rat livers for 1 h is located between 40 and 43°C.