Bioavailability and biotransformation of 3H-benzo[a]pyrene metabolites in in Situ intestinal preparations of uninduced and BNF-induced channel catfish

The systemic bioavailability and intestinal biotransformation of dietary [G-3H]-3-hydroxy-benzo [a]pyrene (3OH-BaP), benzo[a]pyrene [G-3H]-9-sulfate (BaP-9-SO4) and 9-benzo[a]pyrenyl [G-3H]-β- -glucopyranosiduronic acid (BaP-9-Glu) were evaluated using an in situ isolated perfused intestinal segment of the catfish. 3OH-BaP (2 and 20 μM), BaP-9-SO4 (10 and 40 μM) or BaP-9-Glu (10 and 40 μM) solutions were administered via micelles into the isolated intestinal segment of non-induced and β-naphthoflavone (10 mg/kg diet) induced catfish. Following a 60 min perfusion, the efferent blood, intestinal contents and mucosa were analysed for [3H] content and metabolite profiles. BNF administration did not result in any significant effect upon the transport or metabolism of BaP-9-SO4, BaP-9-Glu or 3OH-BaP. The appearance of radioactivity in all analysed components for all compounds followed a dose-dependent relationship which was modified by bioavailability and biotransformation. BaP-9-SO4 and BaP-9-Glu were readily transported intact from the intestinal lumen to the systemic circulation. 3OH-BaP was extensively biotransformed to BaP-3-SO4 and lesser amounts of BaP-3,6-dione and BaP-3-glucuronide before being absorbed into the blood. These findings support the hypothesis that preconsumptive metabolites and their intestinal biotransformation products are readily available to the systemic circulation of a consumer.