[Effect of cell respiration inhibitors on the formation of structural mutations in human lymphocytes irradiated at different stages of the mitotic cycle].

Human lymphocytes were irradiated by 60Co gamma-rays after 0, 10, 20, 35, 45, 48 and 49.5 h of incubation. Immediately after irradiation sodium cyanide, sodium fluoride or monoiodoacetic acid was given for 2.5 h. Non-irradiated cells were subjected to the same treatments. Chromosomal aberrations were analysed in metaphase cells of the first mitosis. When administered alone, all chemicals increased the frequency of chromatid aberrations. The special analysis showed that these chemicals were not mutagens in a strict sense, as the observed increase of aberration frequency was due to inhibition of repair processes, which increased the probability of manifestation of spontaneous changes (so-called "pseudomutagenesis"). The same chemicals increased the frequency of radiation-induced aberrations during two periods of the mitotic cycle, namely, in the end of the G1 stage and in the G2 stage. It has been recently shown that the inhibitor of DNA synthesis, 5-fluorodeoxyuridine, increased the frequency of radiation-induced aberrations during the same periods. It follows that the process of repair proceeding during these periods requires both DNA synthesis and energy supply.