[Metabolic activation of N-methyl-N-nitrosourea in normal and tumor cells].

N-methyl-N-nitrosourea is metabolised by mouse liver microsomes yielding highly reactive product(s) capable of alkylating cellular macromolecules. Based on cofactor requirement (NADPH, oxygen), inhibition (NaN3) and induction by phenobarbital, 3,4-benz(a)pyrene, and MNU, the reaction is cytochrome P-450-dependent. Analysis of the kinetics and dose dependence of alkylation in vivo and in tissue homogenates confirms the fact that MNU must undergo metabolic activation in vivo.