[Study of the radioprotective effect of the NO-synthase inhibitor L-NAME in Chinese hamster cell culture].

A radioprotective effect of L-NAME was estimated by the yield of the aberrant anaphases after exposure of Chinese hamster cells to different doses of gamma-rays and beta-particles. It was shown that cell treatment with L-NAME before irradiation only decreased the frequency of radiation-induced chromosome aberrations. The equal yield of the aberrant anaphases was found in the cells treated with L-NAME and irradiated with 6 Gy gamma-rays later and in the cells non-treated with L-NAME and irradiated with 3 Gy gamma-rays. The treatment of cells with L-NAME just before and immediately after irradiation did not modify the radiation-induced frequency of the chromosome aberrations. The treatment of cells with L-NAME decreased the level of SH-groups (as estimated by UV-spectrophotometer) and increased the chromatin condensation (as estimated by flow cytometry). It was suggested that radioprotective effect of L-NAVE may be connected with its cooperation with DNA. Condensation of L-NAME on the surface of DNA resulted in increasing of probability of the chemical repair of DNA-radicals after irradiation. Thus, these results indicate the involvement of NO-dependent mechanism of the realization of the radiation-induced damage to the hereditary cell structure and optimal conditions for the realization as well as the conceivable mechanism of radioprotective effect one of the most inhibitors of NO-synthase--L-NAME.