Metabolism of cholate, 7 beta-hydroxy- and 12 beta-hydroxy-isocholates in the rat.

The three epimeric trihydroxy bile salts cholate (C), 7 beta-hydroxy-(7 beta) and 12 beta-hydroxy-(12 beta) isocholate were fed to rats by intubation or in the diet. All three bile salts were well absorbed 7 beta greater than C greater than 12 beta and underwent heavy biotransformations in the enterohepatic circulation 12 beta greater than 7 beta C. The result is a low concentration of unchanged administered bile salt in the bile salt pools, 12 beta less than 7 beta less than C, the percentage figures being 3, 20 and 35%, respectively, after 7 days feeding. In spite of this, the composition of the bile changes, less phospholipid and cholesterol being excreted in the bile per mumol bile salt after feeding, 7 beta and 12 beta compared to C. No significant increase in the faecal fat was seen in rats fed the beta-hydroxy bile salts. Only minor amounts of the radioactivity from the beta-hydroxy bile salts were secreted into the urine, and no more when compared to C.