Short-term carcinogen-induced changes in composition of rat liver chromatin protein.

Changes in the composition of rat liver chromatin protein were detected by electrophoretic analysis 4 h after a single injection of 10-30 mg/kg body weight dimethylnitrosamine. Non-histone bands were reduced in staining intensity and increases in all F2 histone subfractions were observed. The staining intensity of F1 and F3 histone was unchanged throughout the experiment. By 24 h after administration of a non-necrotizing dose of dimethylnitrosamine, the proportion of chromatin proteins, when compared to controls, was marked by an increase in non-histones and decreased amounts of F2 histone subfractions. Slight differences between treated and control were evident at 48 h, suggesting that at least this interval is required for recovery from in vivo methylation.