Role of mixed-function oxidases and non-protein sulfhydryl content in [14C]-2-chloro-4-acetotoluidide binding to liver and kidney in starlings

The compound 2-chloro-4-acetotoluidide (CAT) is highly toxic to many avian species, including the starling. In our earlier work, we demonstrated the covalent binding of radioactivity from [14C]-CAT to liver and kidneys of the starling. In the present study, the effects of inducers of mixed-function oxidase (MFO) and non-protein sulfhydryl (NPSH) depletor on the total and covalent binding of [14C]-CAT radioactivity to liver and kidney of the starling were examined. The total and covalently bound radioactivity from [14C]-CAT to liver and kidney were decreased significantly in the starling pretreated with the MFO inducer, 3-methylcholanthrene. However, pretreatment with phenobarbital, another inducer of MFO, had no effect. Pretreatment with the inhibitor of MFO, SKF 525-A, reduced the covalent binding of [14C]-CAT radioactivity to liver but not to kidney. There was no reduction in the NPSH content of liver or kidney following intravenous administration of CAT (3.5 mg kg-1). Reduction of NPSH levels in the liver or kidney following treatment with diethyl maleate caused a significant increase in the covalent binding of [14C]-CAT to kidney but not to liver.