Uptake and biotransformation of 6,7-dimethylquinoline and 6,8-dimethylquinoline by rainbow trout (Salmo gairdneri)

1. 6,7-Dimethylquinoline (6,7-DMQ) is readily taken up by rainbow trout and bioconcentrated in tissue after exposure to ca 1 mg/l for 7.5 h. Mean bioconcentration factors (from water) were 21, 18, 6 and 14 for bile, liver, muscle and carcass respectively. Mean tissue concentrations after 69-96 h depuration were ND, ND, 0.54 and 0.48 micrograms/g for bile, liver, muscle and carcass respectively. 2. Major metabolites, following exposure to 6,7-DMQ, were conjugates (glucuronide or sulphate) of 7-hydroxymethyl-6-methylquinoline and 6-hydroxymethyl-7-methylquinoline. Mean concentration of metabolites in the bile were 500 micrograms/g after 7.5 h exposure to ca 1 mg/l and 1367 micrograms/g after 9.5 h exposure to ca 1 mg/l and 69 h depuration. 3. 6,8-Dimethylquinoline (6,8-DMQ) is also readily bioconcentrated in fish tissue after exposure to ca 1 mg/l. Mean bioconcentration factors (from water) were 23, 20, 13 and 25 for bile, liver, muscle and carcass respectively. Mean tissue concentrations after 7 h exposure to ca 1 mg/l and 63 h depuration were 4.0, 0.67, 0.49, and 3.2 micrograms/g respectively for bile, liver, muscle and carcass. 4. Major metabolites, following exposure to 6,8-DMQ were conjugates (glucuronide or sulphate) of 6,8-dimethyl-5-hydroxyquinoline, 6,8-dimethyl-7-hydroxyquinoline, 6,8-dimethyl-3-hydroxyquinoline and 6-hydroxymethyl-8-methylquinoline. Mean concentration of metabolites in the bile were 1278 micrograms/g after exposure to ca 1 mg/l for 8 h and 1031 micrograms/g after exposure to ca 1 mg/l for 7 h and 63 h depuration.