Effect of enzymatic induction and inhibition on cyclophosphamide-induced sister chromatid exchange in vivo.

The influence of the enzymatic inducer beta-naphthoflavone (BNF) and of the inhibitors alpha-naphthoflavone (ANF) and 2-diethylaminoethyl-2,2-diphenylvalerate HCl (SKF 525-A) on the frequency of sister chromatid exchanges (SCE) induced by cyclophosphamide (CPA) was studied in vivo in C57BL/6J male mice. Neither inducer nor inhibitors substantially modified the SCE level induced by 5 or 10 mg/kg CPA. The enzymatic induction by BNF was effective as treated animals showed a reduced paralysis time by zoxazolamine whereas ANF appeared to be ineffective. The enzymatic inhibition by SKF 525-A was confirmed by a longer sleeping time in pentobarbital-treated mice and also by a longer paralysis in zoxazolamine-treated mice. The lower susceptibility to CPA-induced SCEs of C57BL/6J mice relative to DBA/2 strain observed in a previous work seems not to be simply related to Ah locus mediated metabolism.