[A comparative study of the action of 1-methyl-1-nitrosourea and 1,3-dimethyl-1-nitrosourea on tumor cell DNA in vitro and in vivo by the alkaline elution method].

DNA damage of the tumor cells was studied by the method of alkali elution from filters after introduction of 1-methyl-1-nitrosourea (MNU) and 1,3-dimethyl-1-nitrosourea (DMNU) to mice with Ehrlich ascites carcinoma or after treatment of the cultivated cells with these drugs. DNA was essay fluorometrically using DAPI. The degree of DNA damage was characterized by the constant of the alkali elution rate (Kae), which was estimated according to the anamorphism of the kinetic curves of elution. It was shown that in the case of MNU application the tumor cell DNA was damaged to a greater extent than in the case of DMNU application. Kae increased with the concentration of drugs. A correlation was established between the antitumor activity of the drug (kappa), K(ae), and the number of chromosome defects per cell (gaps, deletions, microfragments, ring chromosomes, and translocations). This suggests that kappa is due both to DNA damage and chromosome defects.