3-Methylcholanthrene does not induce in vitro xenobiotic metabolism in spiny lobster hepatopancreas, or affect in vivo disposition of benzo[a]pyrene.

Administration of 3-methylcholanthrene (10 mg/kg) i.m. to spiny lobsters, Panulirus argus, did not cause induction of the cytochrome P-450 content of hepatopancreas microsomes. The rate of oxidation of benzo[a]pyrene or 7-ethoxyresorufin in reductase-fortified preparations of hepatopancreas microsomes was the same for corn oil-treated or 3-methylcholanthrene-treated lobsters. Administration of 3-methylcholanthrene (10 mg/kg) i.m. to spiny lobsters one week prior to an i.v. dose of [14C]benzo[a]pyrene (1 mg/kg) did not influence the disposition of the radiolabelled benzo[a]pyrene in lobsters. At one week after the dose of [14C]benzo[a]pyrene, approximately 40% of the dose of [14C]benzo[a]pyrene remained in the lobsters, regardless of treatment. The digestive tract (hepatopancreas, intestinal contents, stomach and intestine) contained most (86%) of the 14C remaining in the lobsters.