IN-VITRO METABOLISM OF 3,3',4,4'-TETRACHLOROBIPHENYL IN RELATION TO ETHOXYRESORUFIN-O-DEETHYLASE ACTIVITY IN LIVER-MICROSOMES OF SOME WILDLIFE SPECIES AND RAT

A qualitative study was performed of the capacity of hepatic microsome s of several wildlife species to metabolize 3,3',4,4'-tetrachlorobiphe nyl (TCB). Hepatic microsomes of species environmentally exposed to po lychlorinated biphenyls (PCBs): harbour porpoise (Phocoena phocoena), harbour seal (Phoca vitulina), common tern (Stema hirundo), and hepati c microsomes from species experimentally exposed to PCBs: elder duck ( Somateria mollissima), rainbow trout (Salmo gairdneri), flounder (Plat ichthys flesus), and Wistar rat, were incubated with C-14-labelled TCB ([C-14]TCB). The mammals and birds were able to metabolize TCB at a r ate that correlated with their ethoxyresorufin-O-deethylase (EROD) act ivity. No [C-14]TCB metabolism was observed in the fish, despite eleva ted EROD activity in the trout. HPLC analysis of diisopropylether extr acts of the microsomal incubations indicated the presence of 4-OH-, 5- OH-, and 6-OH-tetrachlorobiphenyl metabolites and a yet unidentified m etabolite. The ratio of the different hydroxy metabolites formed varie d for the various species.