STUDIES ON THE EXCRETION OF DIRECT BILIRUBINS FROM THE LIVER

Part 2. Differnce of chemical properties of bilirubin sulfate isomers and their excretion into the rat bile

Abstract

Properties of chemically synthesized bilirubin sulfate isomers were examined by thin layer chromatography and photochemical methods. Further more, their excretion rates into the bile after intravenous loading to Wistar strain rat and heterozygous Gunn rat were studied. The bilirubin sulfate isomers were synthesized chemically by the method of Watson from crystallized bilirubin, which were separated into three fractions by McDonagh's thin layer chromatography. The following results were obtained:
1) Absorption maxima of bilirubin-IIIα sulfate, -IXα sulfate, -XIIIα sulfate in methanol solution were determind to be 443 mμ., 445 mμ and 448 mμ., respectively. Absorption maxima of their diazotized sulfanylate solution pH 5.4 were 555 mμ, 550 mμ. and 545 mμ, respectively which moved to 576 mμ, 574 mμ and 572 mμ, respectively, after acidification with hydrochloric acid to pH 1.0.
2) The Rfs of bilirubin-IIIα sulfate, -IXα sulfate and -XIIIα sulfate on the thin layer chromatography were 0.15, 0.19 and 0.22 respecitvely.
3) The Rfs of bilirubin extracted from bile which excreted in the first two hours after intravenous injection of bilirubin sulfate isomers were consistent with those of chemically synthesized bilirubin sulfate isomers.
4) The excretion ratio up to eight hours following the loading of bilirubin sulfate isomers in Gunn rat were 65.4+15.4% of bilirubin-IIIα sulfate, 57.4+7.0% of -IXα sulfate and 70.9+11.6% of -XIIIα sulfate, respectivey. In the Wistar strain rat they were 70.4+4.8%, 62.5+4.5% and 77.7+12.6%, respectively. There was no significant difference in the excretion ratios of the isomers between the Gunn rat and Wistar atrin rat. These results suggest that each of bilirubin sulfate isomer is easily excreted in the bile without modification.