Comparison of the biliary excretion of the four isomers of bilirubin-IX in Wistar and homozygous Gunn rats.
The biliary excretion of the four isomers of bilirubin-IX was studied in Wistar rats (JJ) and homozygous Gunn rats (jj). Synthetic preparations of 14C-labelled pigments were used. 1. After intravenous administration, the alpha-isomer was rapidly excreted in conjugated form in bile of Wistar rats. In Gunn rats excretion was insignificant. In contrast, both rat species promptly excreted the non-alpha-isomers at rates that were comparable with that found for bilirubin-IXalpha in Wistar rats. 2. In normal rats about 16% of the beta- and delta-isomers and at least 50% of the gamma-isomer were excreted as ester conjugates of the injected parent bile pigments. Conjugation of the beta- and delta-isomers had occurred exclusively at the carboxyl groups of pyrrole ring D and C respectively. For bilirubin-IXgamma no preference for any carboxyl group could be established. 3. In homozygous Gunn rats the non-alpha-isomers were apparently excreted chemically unaltered. This suggests that, as for bilirubin-IXalpha, conjugation of the non-alpha-isomers is also deficient in Gunn rats.
D000818:Animals; D001391:Azo Compounds / Q000032:analysis; D001646:Bile / Q000032:analysis*; D001654:Bile Pigments / Q000032:analysis*; D001663:Bilirubin / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D004951:Esterification; D006720:Homozygote; D007536:Isomerism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013045:Species Specificity
D001391:Azo Compounds; D001654:Bile Pigments; D001663:Bilirubin