Urinary excretion of bile acids in bile duct-ligated rats.
BACKGROUND
In patients with complete bile duct obstruction, the only pathway of bile acid elimination is through the urine. However, the urinary excretion of various bile acid conjugates in the presence of bile duct obstruction has not been clarified. Given this factor, the urinary excretion of various bile acids was compared in rats that were bile duct-ligated for 3 days.


METHODS
After urinary bladder cannulation, radiolabeled bile acids were intravenously injected, and urine samples were collected every 2 h for 6 h, and radioactivity was counted.


RESULTS
Urinary excretion (cumulative percent dose during 6 h) of taurocholate and cholate was similar (19.3% and 16.8%). Urinary excretion of tauroursodeoxycholate, lithocholate, and taurolithocholate-sulfate was less effective (12.7%, 9.8% and 2.1%, respectively). Cholate was mostly conjugated with taurine, and lithocholate was mostly conjugated with taurine and further hydroxylated.


CONCLUSIONS
These results indicate that unconjugated bile acids were taken up by the liver and excreted into the blood after further biotransformation even under conditions of complete bile duct obstruction. Although bile acid sulfates are the major bile acids in the urine of patients with obstructive jaundice, monohydroxylated bile acids are considered not to be so effectively excreted into the urine, even with conjugation with taurine and sulfate, in rats.
Takada
Yukiko
Y
Department of Medicine, Teikyo University School of Medicine, Itabashi-ku, Tokyo 173-8605, Japan.
Sano
Naoyo
N
Takikawa
Hajime
H
D000818:Animals; D001647:Bile Acids and Salts / Q000652:urine*; D002250:Carbon Radioisotopes; D002779:Cholestasis / Q000652:urine*; D002855:Chromatography, Thin Layer; D003135:Common Bile Duct / Q000601:surgery; D003137:Common Bile Duct Diseases / Q000652:urine*; D008026:Ligation; D008099:Liver / Q000378:metabolism; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
D001647:Bile Acids and Salts; D002250:Carbon Radioisotopes