Further studies on the metabolism of dimethylnitrosamine by rat liver in vitro [proceedings].

(Fig. 1 ) . These compounds also had some effect on the proportion of the 14C recovered in the urine. N-Nitrosopyrrolidine inhibits the metabolism of dimethylnitrosamine to formaldehyde by rat liver l O O O O g supernatant. The form of the dependence of the rate of dimethylnitrosamine metabolism to formaldehyde on inhibitor concentration (shown in Fig. 2) suggests that there is a competitive effect. These results taken together strongly suggest that there may be a close relationship between the rate-determining step(s) in the metabolism of the two environmentally important carcinogens dimethylnitrosamine and N-nitrosopyrrolidine.