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

Abstract

The three epimeric trihydroxy bile salts cholate (C), 7β-hydroxy-(7β) and 12β-hydroxy-(12β) isocholate were fed to rats by intubation or in the diet. All three bile salts were well absorbed 7β> C> 12β and underwent heavy biotransformations in the enterohepatic circulation 12β>7β>C. The result is a low concentration of unchanged administered bile salt in the bile salt pools, 12β<7β<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 μmol bile salt after feeding, 7β and 12β compared to C. No significant increase in the faecal fat was seen in rats fed the β-hydroxy bile salts. Only minor amounts of the radioactivity from the β-hydroxy bile salts were secreted into the urine, and no more when compared to C.

Key Words:

• bile salts
• bile lipids
• biotransformation