[Immediate and delayed effects of low doses of beta-radiation in mammalian cells in culture].

We have carried out the comparative examination into the efficacy of induction of NO and superoxide anion by incorporated and unincorporated sources of ionizing radiation in endotheliocytes (line ECV 304) and carcinoma cells (line HeLa G63) expressing various forms of NO-synthases. The increased intracellular nitric oxide levels were observed after exposure of the cells to beta-particles of 3H-thymidine and 3H2O, as well as to gamma-rays of 137Cs in HeLa G63 cells expressing the inducible forms of NO-synthases. A higher incidence of the intracellular NO level was observed after exposure to beta-particles of 3H2O than to beta-particles of 3H-thymidine or gamma-rays of 137Cs even though 3H-thymidine and gamma-rays elicited more chromosomal damages. Modification of the intracellular superoxide level was shown to have a similar dynamics of the changes in time for the both cellular lines. Shortly after irradiation, the intracellular superoxide level was lower than in non-irradiated cells, and then it became higher than the control level. The increased intracellular superoxide and NO levels were observed after exposure of the cells to beta-particles of 3H-thymidine and 3H2O, as well as to gamma-rays of 137Cs in the progeny of irradiated cells. Modification of the intracellular superoxide level was accompanied by decondensation of the cellular chromatin. A higher intracellular free radical level in the progeny of irradiated cells along with decondensation of cellular chromatin, as well as the absence of correlation between a radiation-induced structural damage of chromosomes and intracellular free radical level allow us to speculate in favor of the participation of epigenetic inheritance mechanisms.