Experimental study on the bilirubin metabolism after major hepatectomy: alterations in the proportions of bile bilirubin subfractions.

Bilirubin metabolism after major hepatectomy was investigated experimentally using rats. After a 70% and an 80% hepatectomy, proportions of bilirubin diglucuronide (BDG) decreased, and reversely, those of bilirubin monoglucuronide (BMG) increased. These changes were even more remarkable after an 80% hepatectomy. Parallel to the decrease in the proportions of BDG, the concentrations of uridine diphosphoglucuronic acid (UDP-GA) in the remnant liver decreased, and there was a significant correlation between the changes in BDG and UDP-GA. Although UDP-glucuronyltransferase (UDP-GT) activity and energy charge of the remnant liver also decreased after surgery, these decreases were mild and returned to the control level earlier than BDG. And there was no significant correlation between the changes in BDG and those in UDP-GT activity and energy charge. In this study, the decrease of the proportions of BDG in the bile juice was long term after partial hepatectomy and the period of the decrease became longer according to the augmentation of the volume of the hepatectomized liver. We clarified that the process of the UDP-GA production was inhibited after hepatectomy and the decrease of the proportions of BDG was derived from a deficiency of substrate of the glucuronidation, UDP-GA.