Uptake and excretion of benzo[a]pyrene and its metabolites by the rat pancreas.

Following intravenous administration of [3H]benzo[a]pyrene ([3H]BP) to rats, uptake of radioactivity by the pancreas, per g of tissue, was approximately 16% of that of the liver. At 5 min following administration, unmetabolized BP in the pancreas, liver, and blood constituted 79, 50, and 49% of total BP uptake, respectively. The total uptake and unmetabolized BP in these tissues declined in a biphasic manner over the 2-hr observation period, during which only 0.03% of the total administered dose was excreted in pancreatic juice, as compared to 39% in bile; all radioactivity in pancreatic juice and bile was due to polar BP metabolites, including 3-hydroxy-BP. Pretreatment of rats with methylcholanthrene induced a significant increase in biliary, but not pancreatic, excretion of radioactivity. Administration of secretagogues caused a 2-fold increase in pancreatic, but not biliary, radioactivity.