Journal of Lipid Research, Vol 21, 186-191, Copyright © 1980 by Lipid Research, Inc.
Competitive inhibition of side chain oxidation of 3 alpha, 7 alpha- dihydroxy-5 beta-cholestan-26-oic acid by 3 alpha, 7 alpha, 12 alpha- trihydroxy-5 beta-cholestan-26-oic acid in the hamster
OW Cass, GC Williams and RF Hanson
3 alpha,7 alpha-dihydroxy-5 beta-cholestan-26-oic acid (DHCA) and 3 alpha,7
alpha,12 alpha-trihydroxy-5 beta-cholestan-26-oic acid (THCA) are
metabolized into chenodeoxycholic acid and cholic acid, respectively,
through oxidation and cleavage of the terminal three carbons of the side
chain. The present study was designed to determine if the same or different
side chain oxidation systems are used by these compounds in the bile
fistula hamster model. Although a single injection of [3H]THCA is nearly
completely metabolized into cholic acid, only about 50% is converted into
cholic acid when THCA is infused at a rate of 0.083 mumol/min. The
remainder is excreted in the bile unchanged indicating saturation of the
side chain oxidation system. Fifty-nine +/- 1.1% (+/- 1SEM) of a single
injection of [3H]DHCA is metabolized into chenodeoxycholic acid in bile
fistula hamsters infused with either saline or cholic acid at a rate of
0.083 mumol/min. The remainder was excreted as several other metabolic
products including cholic acid. However, when [3H]DHCA was administered
during an 0.083 mumol/min infusion of THCA, only 39.0 +/- 4.5% of the
radioactivity in bile was identified as chenodeoxycholic acid. Thus, this
study indicates that DHCA and THCA share at least one of the enzymes
involved in side chain oxidation.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
