The toxicokinetics of benzo[a]pyrene in juvenile coho salmon, Oncorhynchus kisutch, during smoltification
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| Authors: | Seubert, JM; Kennedy, CJ |
| Year: | 1997 |
| Journal: | Fish Physiology and Biochemistry 16: 437-447 |
| Title: | The toxicokinetics of benzo[a]pyrene in juvenile coho salmon, Oncorhynchus kisutch, during smoltification |
| Abstract: | The activities of Phase I and Phase II biotransformation enzymes in the livers of yearling coho salmon (Oncorhynchus kisutch), were measured biweekly from February until the release date from the hatchery in mid-June, in order to observe any alterations in baseline levels during smoltification. Peak enzyme activities occurred in February and March and then declined through to June. Total cytochrome P450 levels ranged from 0.024+/-0.009 to 0.095+/-0.010 nmol mg(-1) microsomal protein, ethoxyresorufin O-deethylase activity ranged from 2.74+/-0.75 to 9.94+/-0.85 pmol min(-1) mg(-1) microsomal protein, and glutathione S-transferase activity ranged from 0.07+/-0.01 to 0.33+/-0.01 mu mol min(-1) mg(-1) cytosolic protein during this period. Following an intraperitoneal injection of [H-3]benzo[a]pyrene (B[a]P), elimination occurred rapidly (>71% excreted into the bile within 24h) from February to June. Although the distribution of B[a]P in tissues changed through the sampling period, the highest levels of B[a]P-derived radioactivity were found in the liver, bile and fat. Analysis of the bile revealed that 55 to 63% of the radioactivity was Phase I metabolites, 16 to 24% glucuronide conjugates, 8% sulfate conjugates, 7% other conjugates and 6% aqueous-soluble metabolites. These findings suggest that the transformation from freshwater adapted coho 'parr' to 'smolts', can significantly alter biotransformation enzyme activities and the distribution and elimination of xenobiotics such as benzo[a]pyrene in these fish. |
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