title: Cytochrome P450 of small intestinal epithelial cells. Immunochemical characterization of the increase in cytochrome P450 caused by phenobarbital.
abstract: We have studied total cytochrome P450 and the major form of cytochrome P450 increased by phenobarbital in small intestinal epithelial cells and livers of male Sprague-Dawley rats. Using an improved method for preparing microsomes from intestinal epithelial cells, we find that concentrations of total cytochrome P450 in intestinal cell microsomes are 10% of those in liver microsomes, and that this percentage is unchanged after phenobarbital treatment. In untreated rats, less than 5% of total cytochrome P450 of liver or intestinal epithelium is the form induced by phenobarbital, as measured by rocket immunoelectrophoresis. In phenobarbital-treated rats, the major phenobarbital-induced form accounts for approximately 50% of the total in both organs. In the small intestine of phenobarbital-treated rats, the concentrations of total cytochrome P450 and of the major phenobarbital-induced form increase concurrently as epithelial cells mature from crypt to upper villus. Concentrations of total cytochrome P450 and of the major phenobarbital-induced form in the proximal two-thirds of the rat small intestine are twofold higher than in the distal third. Immunoblotting performed with a monoclonal antibody to the major phenobarbital-induced form of cytochrome P450 from rat liver revealed a subtle difference between this form in liver and intestine.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis* / Q000276:immunology; D004848:Epithelium; D007122:Immunoelectrophoresis; D007421:Intestine, Small / Q000032:analysis / Q000187:drug effects* / Q000276:immunology; D008099:Liver / Q000032:analysis / Q000187:drug effects / Q000276:immunology; D008297:Male; D008861:Microsomes / Q000032:analysis / Q000187:drug effects / Q000276:immunology; D010634:Phenobarbital / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000911:Antibodies, Monoclonal; D003577:Cytochrome P-450 Enzyme System; D010634:Phenobarbital