[Changes in cellular radiosensitivity by modifying the cytoplasmic membranes]

Area of Science:

• Cellular radiosensitivity
• Biophysical effects of ions on cell membranes
• Radiation biology

Background:

• The impact of divalent metal ions on cellular responses to ionizing radiation is not fully understood.
• Understanding these interactions is crucial for predicting radiation damage and developing protective strategies.
• Previous studies have explored ion effects on cell viability and membrane properties separately.

Purpose of the Study:

• To investigate the influence of magnesium (Mg2+) and uranyl (UO2(2+)) ions on the radiosensitivity of mouse myeloma and E. coli cells.
• To elucidate the mechanisms by which these ions affect cellular radiosensitivity, particularly concerning cell membrane interactions.
• To compare the effects of Mg2+ on cells and bilayer lipid membranes (BLM) to understand its role in radiosensitivity.

Main Methods:

• Exposure of E. coli and mouse myeloma cells to varying concentrations of Mg2+ and UO2(2+) ions.
• Irradiation of cells in the presence and absence of these ions.
• Assessment of cell viability and survival rates post-irradiation.
• Comparison with existing data on the effects of these ions on bilayer lipid membranes (BLM).

Main Results:

• Mg2+ ions (10^-4 M) did not affect the basal viability of either cell type.
• The presence of Mg2+ during irradiation reduced the survival rate of E. coli cells, indicating increased radiosensitivity.
• Post-irradiation addition of Mg2+ did not alter E. coli radiosensitivity.
• UO2(2+) ions (10^-4 M) increased the radioresistance of E. coli cells.
• Mg2+ ions are hypothesized to increase membrane positive charge, enhancing radiosensitivity by promoting radiolysis products.
• UO2(2+) ions are suggested to increase radioresistance by enhancing membrane viscosity.

Conclusions:

• Mg2+ ions modulate E. coli radiosensitivity primarily when present during irradiation, likely through membrane charge alterations.
• UO2(2+) ions confer radioresistance to E. coli, potentially by increasing membrane viscosity.
• Cell membrane properties play a significant role in mediating the effects of metal ions on cellular radiosensitivity.