Abstract
In isolated rat livers, the total amount of bile produced decreased linearly with increasing ischemic time. The rate of decrease was greater when rat blood was used for perfusion but the lines obtained with each perfusate were coincident when extrapolated to zero ischemic time and the theoretical amount of bile produced at that time agreed reasonably well with measurements made on the bile collected from four livers in situ. None of the other measurements of liver function showed any correlation with ischemic time.
The mean rate of synthesis of urea by livers perfused with rat blood was constant over the 3 hour period at 1.3 μmol/min. A similar rate of synthesis of urea was observed during the first hour of perfusion with bovine erythrocytes, although, thereafter, the rate of synthesis declined. The concentration of ammonia in the rat blood perfusate was maintained at a low level (0.03 μmol/ml), but in the experiments using bovine erythrocytes there was a small increase (0.04 μmol/min) in the amount of ammonia released by the liver. Potassium, released into the acellular fraction of the perfusion fluid at a rate of 0.24 μmol/min in experiments using bovine erythrocytes, probably resulted from hemolysis. The same rate of release was observed during the first two hours of perfusion with rat blood, but the rate increased thereafter. These experiments show clearly that the amount of bile produced by rat liver in vitro is indeed related to the ischemic time during cannulation and excision, but it is not understood how an ischemic time of a few minutes can influence the total amount of bile produced in the subsequent 3 hour period.