Plasma Disappearance of Conjugated and Unconjugated C 14 Bilirubin in the Rat with Obstructive Jaundice

Summary

Uncon jugated (C¹⁴)-bilirubin was administered intravenously to rats with complete biliary obstruction. The plasma disappearance curves of both the conjugated and unconjugated (C¹⁴)-bilirubin fractions were determined using a modified Weber and Schalm technique. More than 70% of the (C¹⁴)-bilirubin radioactivity in the plasma was present as conjugated (C¹⁴)-bilirubin after 15-30 minutes of injecting the unconjugated label. The biological half life of unconjugated (C¹⁴)-bilirubin averaged 53 hours while that of the conjugated form 34 hours. This difference could be explained by the clearance of conjugated (C¹⁴)-bilirubin by the kidney.