Alkylation of meseenger RNA by dimethylnitrosamine

Rats were treated with radioactive dimethylnitrosamine or methyl methanesulphonate and the alkylation of various RNA fractions was determined 4 h later. It was found that after administration of dimethylnitrosamine, hepatic messenger RNA (isolated by binding to oligo(dT)-cellulose) and nuclear RNA were alkylated slightly, but significantly less than ribosomal RNA. After treatment with methyl methanesulphonate nuclear RNA was alkylated to a greater extent than either messenger or ribosomal RNA. The implications of these findings with respect to the mechanism by which dimethylnitrosamine inhibits liver protein synthesis are discussed.