Relative Concentrations of Cytochrome P450-Active Organochlorine Compounds in Liver and Muscle of Rainbow Trout From Lake Ontario

Abstract

The teleost liver is the primary target organ for the induction of cytochrome P450-dependent monooxygenases by chemicals in fish. However, monitoring information on the residues of monooxygenase-inducing organochlorine compounds in fish generally consists of data on the concentrations in muscle tissue or the whole body. We determined the relative concentrations of cytochrome P450-active PCB congeners and organochlorine insecticides in the muscle and liver of rainbow trout ( Oncorhynchus mykiss) sampled from the Ganaraska River on Lake Ontario. There were no significant differences in the mean concentrations of 24 PCB congeners in muscle and liver tissues when concentrations were expressed on a wet weight or a lipid weight basis. Of the 7 other potential cytochrome P450-active organochlorine compounds quantified, only dieldrin was present at significantly higher concentrations in muscle than liver samples, and endrin was present at significantly higher concentrations in liver than muscle. The demonstration of equivalent concentrations of most of these organochlorine compounds in liver and muscle suggests that data on contaminant levels in muscle may be used to evaluate the potential for induction of hepatic monooxygenases in salmonids.