Unconjugated and Conjugated Bilirubin Transport in Normal and Mutant Corriedale Sheep with Dubin-Johnson Syndrome 1

Abstract

Summary

Bilirubin transport was studied in normal and mutant Corriedale sheep with Dubin-Johnson syndrome using ¹⁴C-labeled unconjugated and conjugated bilirubin. Inter-compartmental transfer rates and pool sizes of unconjugated bilirubin (UCB) and of conjugated bilirubin (CB) were calculated by observing the rates of disappearance of injected ¹⁴C-UCB and ¹⁴C-CB from the plasma. The transport efficiencies of UCB and CB from a mixing pool (primarily plasma) to a storage pool (primarily hepatic cells) in the mutants were 22% and 12%, respectively, that of normal sheep. Bilirubin excretion efficiency in mutants was approximately 33% that of normal sheep.

Increased UCB and CB plasma concentrations in the mutant Corriedale sheep apparently result from a decreased transport efficiency of both UCB and CB from plasma to liver as well as the defective excretion of CB by the liver into bile.