[Action of ftorafur on the chromosomes of normal and tumorous cells of the Djzungarian hamster in vitro].

The chromosome-breaking effect of antitumor agent ftorafur (0,1 mg/ml) was studied on cell cultures of normal and transformed Djungarian hamster's fibroblasts. After 24 hours of exposition with the drug 79% of aberrant malignant cells was registered, while the chromosomes of normal cells remained undamaged. After ftorafur's action for 2--12 hours and the following removal of the agent the level of aberrant metaphase among normal cells rose to 11--15%. Chromatid breaks were the predominant type of drug-induced aberrations. Thse results confirm the idea that ftorafur blocks the cell cycle of normal fibroblasts and that it's necessary to wash the drug off some period before fuxation in order to reveal its chromosome-breaking effect in metaphase cells. The striking distinctions in susceptibility of normal and malignant cells to the mutagenic effect of ftorafur is partly due to the distrubances of the cell cycle caused by this drug.