Effects of 50-Hz magnetic field exposure on superoxide radical anion formation and HSP70 induction in human K562 cells |
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Authors: | Ann-Christine Mannerling Myrtill Simkó Kjell Hansson Mild Mats-Olof Mattsson |
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Institution: | 1. Life Science Center, Academy of Natural Sciences and Technology, ?rebro University, ?rebro, Sweden 2. Division of Environmental Physiology, Institute for Cell Biology and Biosystems Technology, University of Rostock, Albert-Einstein-Str. 3, 18059, Rostock, Germany 3. Institute of Technology Assessment of the Austrian Academy of Sciences, Vienna, Austria 4. Radiation Physics, Department of Radiation Sciences, Ume? University, Ume?, Sweden
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Abstract: | Epidemiological studies suggest a correlation between exposure to low-level extremely low-frequency (ELF) magnetic fields
(MF) and certain cancers and neurodegenerative diseases. Experimental studies have not provided any mechanism for such effects,
although at flux density levels significantly higher than the ones encountered in epidemiological studies, radical homoeostasis
and levels of stress response proteins can be affected. Here, we report on the influence of MF exposure (50-Hz sine wave;
1 h; 0.025–0.10 mT; vertical or horizontal MF exposure direction) on different cellular parameters (proliferation, cell cycle
distribution, superoxide radical anion, and HSP70 protein levels) in the human leukaemia cell line K562. The positive control
heat treatment (42°C, 1 h) did not affect either cell proliferation or superoxide radical anion production but caused accumulation
of cells in the G2 phase and increased the stress protein HSP70. MF exposure (0.10 mT, 1 h) did not affect either cell cycle
kinetics or proliferation. Both vertical and horizontal MF exposures for 1 h caused significantly and transiently increased
HSP70 levels (>twofold), at several flux densities, compared to sham controls and also compared to heat treatment. This exposure
also increased (30–40%) the levels of the superoxide radical anion, comparable to the positive control PMA. Addition of free
radical scavengers (melatonin or 1,10-phenantroline) inhibited the MF-induced increase in HSP70. In conclusion, an early response
to ELF MF in K562 cells seems to be an increased amount of oxygen radicals, leading to HSP70 induction. Furthermore, the results
suggest that there is a flux density threshold where 50-Hz MF exerts its effects on K562 cells, at or below 0.025 mT, and
also that it is the MF, and not the induced electric field, which is the active parameter. |
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