title: [NO-dependent pathway of the modifying of the cellular sensitivity to gamma- and neutron irradiation].
abstract: The modifying effect of L-NAME, the NO-synthase inhibitor and D-NAME, the inactive enantiomer was investigated in human carcinoma cells (HeLa) and Chinese hamster fibroblasts (V-79) exposed to different doses of gamma-rays and 0.85 MeV neutrons. We estimated the level of the chromosome aberrations manifested as the bridges and fragments in anaphases. Radioprotective effect of L-NAME showed the inverse dependence on the exposure dose and at low doses (1 Gy) it was higher in the V-79 cells, than in the HeLa cells. However, at high doses (3, 4, 6 Gy) the efficiency of L-NAME for these cellular lines was almost equal (DFR = 2). The modifying effect of L-NAME was almost equal for gamma-irradiation and neutrons, although the exposure of V-79 cells to neutrons induced more the asymmetric chromosome aberrations (RBE = 4). The D-NAME had no effect on the level of the radiation-induced chromosome aberrations, although D-NAME treatment of cells increased the chromatin condensation, as well as L-NAME. The counteractive condensation does not play the major role in the radioprotective effect of L-NAME. We suggest that the radioprotective effect of L-NAME resulted from the action on the generation reactive radicals due to the inhibition of the inducible NO-synthase.
authors.affiliation: Petersburg Nuclear Physics Institute, Russian Academy of Science, St. Petersburg, 188300 Russia. giliano@omrb.pnpi.spb.ru
authors.forename: N Ia
authors.initials: NIa
authors.lastname: Gil'iano
authors.forename: G N
authors.initials: GN
authors.lastname: Bondarev
authors.forename: L A
authors.initials: LA
authors.lastname: Noskin
authors.forename: R F
authors.initials: RF
authors.lastname: Fedortseva
authors.forename: G I
authors.initials: GI
authors.lastname: Krasotskaia
mesh_terms: D000705:Anaphase; D000818:Animals; D002477:Cells / Q000528:radiation effects*; D002588:Cesium Radioisotopes; D002869:Chromosome Aberrations; D006224:Cricetinae; D003412:Cricetulus; D004307:Dose-Response Relationship, Radiation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000528:radiation effects; D005720:Gamma Rays; D006367:HeLa Cells; D006801:Humans; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D009502:Neutrons; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D011829:Radiation Dosage; D011837:Radiation-Protective Agents / Q000494:pharmacology*
chemical_list: D002588:Cesium Radioisotopes; D004791:Enzyme Inhibitors; D011837:Radiation-Protective Agents; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester