Effect of cadmium in vitro on benzphetamine-N-demethylation and ethoxyresorufin-O-deethylation in rats of different age.

The in vitro influence of CdSO4 on the liver microsomal benzphetamine-N-demethylation and ethoxyresorufin-O-deethylation activities in male Wistar rats/age 10, 30, 60 and 240 days/as well as the type of inhibition were studied after phenobarbital or beta-naphthoflavone pretreatment. Both reactions were inhibited by CdSO4 in dependence on concentration in all age groups. After phenobarbital pretreatment the inhibition of N-demethylation was slightly pronounced in 10-day old rats. In 10 and 30-days old rats the type of inhibition was competitive while in 60 and 240-days old rats a non-competitive type of inhibition was observed. O-deethylation of ethoxyresorufin was inhibited also in 10-day old rats, the inhibition type was non-competitive in all age groups. After beta-naphthoflavone pretreatment N-demethylation was inhibited competitively in all age groups. The inhibition of O-deethylation was more pronounced in 30-day old rats, in other age groups the inhibition was weak but concentration dependent. The type of inhibition was noncompetitive for all age groups studied.