[Changes in cellular radiosensitivity by modifying the cytoplasmic membranes]

The radiosensitivity of mouse myeloma and E. coli cells in the presence of Mg2+ and UO2(2+) ions has been investigated. It has been shown that Mg2+ ions (10(-4) M) do not influence the viability of E. coli and mouse myeloma cells. The presence of Mg2+ ions during irradiation reduces the survival rate of E. coli cells, but the addition of Mg2+ ions after irradiation does not influence the radiosensitivity of E. coli cells. Comparison of the results on the influence of Mg2+ ions upon cells and bilayer lipid membranes (BLM) permits us to suppose that Mg2+ ions increase the positive charge of the membranes thus promoting the increase in the number of short-lived radiolysis products which impair membranes and increase cell radiosensitivity. UO2(2+) ions (10(-4) M) increase the radioresistance of E. coli cells which can be associated with the increase in the lateral membrane viscosity, as it was shown in the studies on BLM.