Occurrence of sulfated 5alpha-cholanoates in rat bile.

Bile acids in bile from male and female rats with cannulated bile ducts have been analyzed by repetitive scanning gas-liquid chromatography-mass spectrometry after initial fractionation of conjugate classes on diethylaminohydroxypropyl Sephadex LH-20. Sex differences were observed in the amounts and types of bile acids in the sulfate fraction. The proportion of total bile acids excreted as sulfates was higher in female (0.9-1.3%) than in male (0.1-0.2%) rats. Most of the sulfated bile acids had a 5alpha configuration, allochenodeoxycholic acid being the major compound in bile from female rats. This bile acid was also present in the nonsulfate fraction but could not be found in bile from male rats. The results indicate that gas-liquid chromatography-mass spectrometry has to be used to provide sufficient specificity in the bile acid analyses. Thus, compounds from the sulfate fraction having the retention times of cholic and chenodeoxycholic acid derivatives were found to be due to derivatives of the 3beta,5alpha-isomers of these bile acids.