Chronic inhalation effects of trichloroethylene on hepatic microsomal mixed function oxidase system in rats

Abstract

Inhalation effects of trichloroethylene, at levels of 0, 200 and 600 ppm for a period of 4 and 12 weeks, on the contents of hepatic microsomal protein, cytochrome P450, cytochrome b5, and on the activities of NADPH cytochrome C reductase, aminopyrine N‐demethylase and aniline hydroxylase were investigated. Body weight remained unaltered at 200 ppm level, whereas at 600 ppm level a significant decrease in body weight was observed. Liver weight showed increases at an exposure level of 200 ppm by the end of 4 and 12 weeks. Relative liver weight (% body weight) showed an increase at 200 and 600 ppm level by the end of week 4, whereas, after 12 weeks increase was observed only in animals exposed to the 600 ppm level. Hepatic microsomal protein was decreased by the end of 4 weeks at both the exposure levels. Cytochrome P450 and cytochrome b, contents were increased at the 200ppm level after 4 and 12 weeks. NADPH cytochrome C reductase activity showed a marked increase at both the 200 and 600 ppm levels after 4 and 12 weeks. Aminopyrine N‐demethylase activity was increased at the 200 ppm level and decreased at the 600 ppm level by the end of 4 weeks, whereas, at the end of 12 weeks the aminopyrine N‐demethylase activity was near control values. Aniline hydroxylase activity was increased at the 200 ppm level after 4 and 12 weeks. Similarly, at the 600 ppm level aniline hydroxylase activity was increased after 12 weeks.