[The role of rat liver microsomes in the metabolism of methylmethacrylate to formaldehyde].

Rat liver microsomal carboxylesterase catalyzed hydrolysis of butyl methacrylate (BMA), butyl acrylate (BA), methyl acrylate (MA) and methyl methacrylate (MMA). The rate of butanol formation from BA and BMA was 4-fold higher as compared with methanol production from MA and MMA. Methanol was oxidized to formaldehyde at the next step of microsomal metabolism. The rate of methanol oxidation was increased 2.2-fold after addition of the NADPH-generating system into the incubation medium. In the mixture containing MMA, NADPH-generating system and liver microsomes, preinduced with phenobarbital or methyl cholanthrene, the rate of formaldehyde generation was increased 7- and 2-fold, respectively, as compared with the analogous experiments involving liver microsomes of control rats. Production of methanol and generation of formaldehyde were not detected after incubation of MMA with inactivated microsomes. The microsomal MMA-methanol oxidizing system was inhibited by CO or after addition of microsomes from rats pretreated with CoCL2. Sodium azide (0.05 mM) decreased 8-fold the rate of formaldehyde generation.