This study aimed at evaluating the effect of acetylsalicylic acid (ASA) (150 and 300 mg/kg b.w.) on urinary trichloroethanol and trichloroacetic acid excretion and the liver cytochrome P-450-dependent monooxygenase system (MFO) in rats treated with trichloroethylene (TRI) alone or with xylene (XYL) at a concentration of 4.5 mmol/m(3) air. The study has shown that xylene equally decreased trichloroacetic acid and trichloroethanol excretion within 48 hours after exposure. Acetylsalicylic acid diminished the excretion of both trichloroethy lene metabolites in a dose-dependent manner, although the effect was weaker than that of xylene.

Liver cytochrome P-450 content tended to increase after both doses of ASA. There were no significant changes in cytochrome b(5) content and the activities of NADPH-cytochrome P-450 and NADH-cytochrome b(5) reductases. TRI decreased cytochrome P-450 and cytochrome b(5) contents and reduced both reductase activities. XYL induced all MFO components.

Acetylsalicylic acid at 150 mg/kg combined with TRI inhalation tended to lower cytochrome bs content and NADH-cytochrome b(5) reductase activity. When given at 300 mg/kg, ASA increased cytochrome P-450 content, while cytochrome b(5) content and NADH-cytochrome: b(5) reductase activity were still decreased, but to a smaller degree when compared with the lower ASA dose.

XYL together with the lower dose of ASA induced the MFO system. Exposure to XYL and the higher dose of ASA elevated cytochrome P-450 content and NADPH-cytochrome P-450 reductase activity and it diminished NADH-cytochrome b(5) reductase activity.

In rats treated simultaneously with ASA, XYL and TRI both cytochromes increased in amount, while the other components of the MFO system did not change.