An in vitro method for obtaining intestinal biotransformation rates for benzo[a]pyrene and diethyl phthalate using using the Sprague-Dawley rat small intestine

An in vitro method for measuring depletion rates for two hydrophobic chemicals, benzo[a]pyrene and diethyl phthalate, has been developed using enterocytes from the proximal 50 cm of the rat small intestine. CYP1A1 activity of the enterocytes was determined and compared to the activity in rat liver S9 fractions by measuring luminescence. The CYP1A1 activity in S9 fractions was approximately 28 times greater than enterocytes (normalized to 106 cells). The apparent depletion rate of benzo[a]pyrene was found to be -0.65(± 0.31 S.E.)x10-3/min/106intestinal cells (n=1) whereas the depletion rate for diethyl phthalate was -0.049(± 0.11 S.E.)/min/106intestinal cells (n=3, p