Aryl hydrocarbon hydroxylase activity in a population of brown bullhead ( Ictalurus nebulosus) environmentally exposed to polycyclic hydrocarbons

Abstract

Two marine flatfish species, English sole (Pleuronectes vetulus) and starry flounder (Platichthys stellatus), were exposed intermuscularly to tributyltin chloride (TBT) at 0.93 mg tin/kg body weight. The tissue concentrations of TBT and its biotransformation products dibutyltin (DBT) and monobutyltin (MBT) were monitored over a three week period. Tributyltin concentrations generally reached a maximum in all tissues by 24 h post exposure. At 24 h, the bile contained the greatest concentrations of tin, followed by the liver and kidney, and then by spleen and muscle. Total butyltins were generally present at higher concentrations in starry flounder than in English sole for all tissues, except gall bladder, at all time points. In both species the concentration of hepatic DBT increased with time. The time-point at which TBT and DBT concentrations became approximately equal was between 1 and 3 days for English sole and between 7 and 14 days for starry flounder. The ratios of hepatic TBT to DBT concentrations at all time-points from 1 to 21 days were significantly lower in English sole compared to starry flounder, suggesting more rapid biotransformation of TBT in English sole. First-order elimination rate constants for TBT in liver were 0.061 and 0.068 day−1 for English sole and starry flounder, respectively. The kidney TBT half-lives were shorter in flatfish than in rainbow trout.