HYDROGEN-PEROXIDE INDUCED REPRODUCTIVE AND INTERPHASE DEATH IN 2 STRAINS OF L5178Y MURINE LYMPHOMA DIFFERING IN RADIATION SENSITIVITY

L5178Y-R (LY-R) and L5178Y-S (LY-S) cells, differing in radiation sensitivity and susceptibility to the radiosensitizing effect of benzamide (Bz) were examined for susceptibility to hydrogen peroxide. Survival and chromatid aberration frequency indicated that LY-R cells were considerably more sensitive to H2O2 than LY-S cells. So, LY strains were found to be inversely cross-sensitive to X/gamma rays and H2O2. The relative resistance to H2O2 corresponded with the previously found twofold difference in catalase activity (Jaworska et al. 1987). At higher concentrations H2O2 treatment caused interphase death, that was delayed by benzamide (Bz, 2 mM), an inhibitor of poly(ADP-ribosylation), to a lesser extent in the more resistant cell subline (LY-S). From the examination of the H2O2 induced increase in the free Ca2+ concentration (with or without 2 mM Bz treatment) with the use of Fura-2 it followed, that the cells responded to the oxidative stress by Ca2+ release. The Ca2+ concentration increase was neither directly related to the killing effect of H2O2 treatment, nor did it correspond with the twofold difference in catalase activity in LY strains.