Induction of microsomal enzymes in the rat liver by inhalation of hydrocarbon solvents.

The possibility of increase of microsomal enzyme activities in the liver by inhaled hydrocarbon solvents has been tested in preliminary investigations with male Wistar rats. The animals were exposed 5 hrs per day to an atmosphere containing various solvents, in a test period of 10 or 28 days. Dichloromethane, carbon tetrachloride, trichloroethylene, and benzene in a concentration of 450-500 ppm caused slight increases of cytochrome P and/or of aminopyrine demethylase activity after 10 days ( P>0.02). At a test period of 28 days already 50 ppm of carbon tetrachloride led to an increase of cytochrome P in the liver cell ( P>0.02). It is reasonable to assume that with prolonged exposure even small solvent concentrations in the respiratory air may lead to undesirable alterations in biotransformation of foreign substances and endogenous compounds in the liver. [ABSTRACT FROM AUTHOR]