[Adaptation to chemical mutagens].

Pre-adaptation of normal and tumor cells to the action of methylnitrosourea was studied. To attain these ends, a single low dose (10 mg/kg) was administered to animals two hours prior to the administration of main therapeutic dose (100 mg/kg) and the number of chromosomal rearrangements was determined. A significant decrease in translocation incidence was observed in metaphases of Ehrlich-ICP ascitic strain. Similar results were obtained on cells of murine bone marrow. The mechanisms of pre-adaptation to the action is discussed.