EFFECTS OF A COMPLEX MIXTURE OF CHEMICAL CONTAMINANTS ON HEPATIC GLUTATHIONE, L-CYSTEINE AND GAMMA-GLUTAMYLCYSTEINE SYNTHETASE IN ENGLISH SOLE (PLEURONECTES VETULUS)

The effects of chemical contaminants on concentrations of hepatic glut athione (GSH), cysteine (L-Cys), and the activity of gamma-glutamylcys teine synthetase (gamma-GCS) were assessed in English sole (Pleuronect es vetulus) in the laboratory and in fish from the Duwamish Waterway, a contaminated urban site in Puget Sound, Washington. In the laborator y studies, fish from a nonurban (reference) site were exposed to an or ganic-solvent extract of sediment from the Duwamish Waterway. Hepatic GSH concentrations significantly increased at 3 d after exposure to th e extract at 1,000 g sediment extracted/kg fish. At this time point, h epatic GSH showed a dose-dependent increase at dosages ranging from 30 0 to 1,600 g sediment extracted/kg fish, whereas fish exposed to a ref erence sediment extract showed no increase. Moreover, the increases in GSH in fish exposed to the contaminated sediment extract were not acc ompanied by changes in either L-Cys concentrations or gamma-GCS activi ty. Similarly, fish sampled directly from the Duwamish Waterway showed increased GSH concentrations but showed no significant differences in L-Cys levels or gamma-GCS activity compared to fish from a reference site. These results substantiate that hepatic GSH in fish is responsiv e to chemical contaminant exposure and further support its use as a bi omarker in environmental monitoring studies. The findings also indicat e that L-Cys availability and induction of gamma-GCS were not major fa ctors in the increase of hepatic GSH in contaminant-exposed English so le.