BILE SECRETORY FUNCTION OF THE ARTERIALIZED VERSUS NONARTERIALIZED RAT LIVER ALLOGRAFT1

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Abstract
Arterialized and nonarterialized rat models of orthotopic liver transplantation are widely used for studying various aspects of graft function. Although bile duct damage has been implicated in graft nonarterialization, any impact on graft secretory function is unknown. This study sought to investigate whether nonarterialized orthotopic liver transplantation (NOLT) is a valid model for studying bile formation after the animal has fully recovered from the perioperative period. Twenty-four-hour bile collections were performed on eight arterialized and eight nonarterialized rats 4 weeks after transplantation to avoid the confounding effects of preservation-reperfusion injury and perioperative stress. Eight unoperated rats were used as control. There was no difference in mortality or biliary complications between the two transplant groups. The nonarterialized rats exhibited a higher serum aminotransferase level, but serum bilirubin was normal. NOLT resulted in more portal lymphocytic infiltration and bile ductular proliferation. Despite these histologic changes, bile duct epithelial cells remained intact, and spontaneous graft rearterialization was evident in the NOLT group. Bile salt secretion, pool size, and synthesis in both transplant groups did not differ from unoperated rats. NOLT did not adversely affect either bile acid-dependent or bile acid-independent flow. Biliary cholesterol secretion was markedly reduced in both transplant groups, resulting in a more favorable cholesterol saturation index. In conclusion, hepatic allograft secretory function is well maintained at 4 weeks even in the absence of hepatic arterial reanastomosis. Compensatory mechanisms possibly prevent irreversible hepatobiliary damage in NOLT. The NOLT model is quite reasonable to study bile formation after transplantation.