[Cellular capacity in tissue culture and in tumors for recovery from the injuries induced by N-methyl-N-nitrosourea].

The survival of the LL cell line in the log-phase of growth, and clonogeneic ability of NKLy/LL tumours, derived from a subcutaneous transplantation of these cells to mice, have been investigated. The survival assay of culture cells and cells in tumours was studied both immediately, and 6--72 hours after the treatment with N-methyl-N-nitrosourea (MNU) in concentrations of 0.05 mg/ml in vitro, and of 12.5--200.0 mg/kg injected in vivo. No repair of potentially lethal damages was noticed in tissue culture during a 72 hours incubation in conditioned medium after the MNU treatment, or in small NKLy/LL tumours when analysed 24 hours after the drug injection. Possible mechanisms of an irrepairable damage induction are discussed.