The effect of biliary obstruction on side chain hydroxylations in the biosynthesis and metabolism of bile acids was studied in the rat. For comparison, several other hydroxylation reactions in bile acid biosynthesis and metabolism were assayed. Biliary obstruction inhibited microsomal 26-hydroxylation of 5β-cholestane-3α, 7α-diol and microsomal 25- and 26-hydroxylation of 5β-cholestane-3α, 7α-12α-triol. Microsomal 7α-hydroxylation of cholesterol and 6β-hydroxylation of lithocholic acid increased significantly, whereas the increase in microsomal 12α-hydroxylation of 5β-cholestane-3α, 7α-diol was less. Mitochondrial 26-hydorxylation of cholesterol, 5-cholestene-3β, 7α-diol, and 7α-hydroxy-4-cholesten-3-one was stimulated, whereas 26-hydroxylation of 5β-cholestane-3α, 7α-diol was not affected and that of 5β-cholestane-3α, 7α, 12α-triol was markedly inhibited. The results indicate that mitochondrial 26-hydroxylation, particularly of substrates that primarily are precursors of chenodeoxycholic acid, plays a more important role in bile acid biosynthesis under conditions of biliary obstruction than under normal conditions.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of lipid research|
|State||Published - 1978|
ASJC Scopus subject areas
- Cell Biology