Metabolism of toluene and trichloroethylene in laboratory rats, pretreatedwith phenobarbital.

Metabolites of toluene (hippuric acid) and trichloroethylene (total trichlo ro compounds) have been estimated in labotratory mts after microsomal induc tion by phenobarbital. Phenobarbital pretreatment accelerated the removal o f total trichloro compounds, however, excretion of hippuric acid was modera tely diminished. Results on cytochrome P450 suggest that microsomal inducti on by phenobarbital was higher in trichloroethylene treated rats than tolue ne treated rats. It is concluded that in addition to distinct substrate spe cificity of CYP450 isozymes several other factors like V-max/Km and QH dete rmine the metabolism of organic solvents.