Rat hepatic microsomal enzyme induction by pretreatment with toxaphene and toxaphene fractions.

The levels of hepatic microsomal induction caused by toxaphene were determined. Young Sprague-Dawley rats (70 g) were administered toxaphene (ip injection, daily for 5 d) at 0, 5, 25, and 100 mg/kg. All doses caused increases in liver/body weight ratio, cytochrome P-450 level, aminopyrine demethylation, and aldrin epoxidation. The aldrin epoxidase activity increased almost 700% at the 100-mg/kg dose. Toxaphene was separated into nonpolar (S-A) and polar (S-B) fractions and administered as before at 25 mg/kg. All treatments caused significant increases in cytochrome P-450, aminopyrine demethylation, and aldrin epoxidation. A comparison of the treatments, however, did not reveal any significant differences between the treatments.