title: Ontogeny of guinea pig liver cholesterol 7 alpha-hydroxylase: unexpected inverse correlation of enzyme activity with expanding bile acid pool.
abstract: Changes in the activity of guinea pig liver cholesterol 7 alpha-hydroxylase (rate limiting enzyme of cholesterol catabolism) from birth to adult life was investigated using a microsomal acetone extraction method (to remove endogenous cholesterol). Contrary to the previously held notion, it was noted that while the total bile acid pool increased progressively with age after birth, hepatic cholesterol 7 alpha-hydroxylase specific activity declined. Neonatal hepatic cholesterol 7 alpha-hydroxylase showed an increase in enzyme activity in response to cell supernatant factors (100,000 xg supernatant) from neonatal livers, but not from adult livers.
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001647:Bile Acids and Salts / Q000032:analysis*; D002790:Cholesterol 7-alpha-Hydroxylase / Q000032:analysis*; D005260:Female; D006168:Guinea Pigs; D008099:Liver / Q000254:growth & development*; D008862:Microsomes, Liver / Q000201:enzymology*; D011247:Pregnancy; D013250:Steroid Hydroxylases / Q000032:analysis*
chemical_list: D001647:Bile Acids and Salts; D013250:Steroid Hydroxylases; D002790:Cholesterol 7-alpha-Hydroxylase