THE HUMAN INTESTINAL CYTOCHROME P450 “PIE”

Abstract
Cytochromes P450 (P450s) 3A, 2C, and 1A2 constitute the major “pieces” of the human liver P450 “pie” and account, on average, for 40, 25, and 18%, respectively, of total immunoquantified P450s (J Pharmacol Exp Ther 270:414–423, 1994). The P450 profile in the human small intestine has not been fully characterized. Therefore, microsomes prepared from mucosal scrapings from the duodenal/jejunal portion of 31 human donor small intestines were analyzed by Western blot using selective P450 antibodies. P450s 3A4, 2C9, 2C19, and 2J2 were detected in all individuals and ranged from 8.8 to 150, 2.9 to 27, 2J2 > 2D6 (8.4, 1.1, 0.9, and 0.5 pmol/mg, respectively). Analysis of a pooled preparation of the 31 donor specimens substantiated these results. In summary, as in the liver, large interindividual variation exists in the expression levels of individual P450s. On average, CYP3A and CYP2C9 represents the major pieces of the intestinal P450 pie, accounting for 80 and 15%, respectively, of total immunoquantified P450s.