In a previous study by the authors (Nakayama et al. 2014), it was found that exposure to a 50 Hz magnetic field increased DNA damage in mouse fibroblasts. However, it had not been investigated whether this phenomenon had any relation to cellular oxidative stress. The authors anticipated that lipopolysaccharides (LPS)-stimulated macrophages might be a suitable model to investigate whether oxidative stress and magnetic fields have synergistic effects because these cells produce large amounts of nitric oxide, which is a source of oxidative stress.
Cells were divided into the following groups: 1) exposure to the magnetic field, 2) sham exposure, 3) exposure to the magnetic field and LPS treatment (10 ng/ml for 1 hour prior to MF exposure), 4) sham exposure and LPS treatment.
Positive control for DNA damage was conducted.
Exposure duration: continuous for 24 hours
|petri dishes in coils inside CO2 incubators
|four square coils made up one Merritt coil, which was constructed with two electric wires wound in parallel around an aluminum frame; cells were exposed to vertically oriented field
|A sham exposure was conducted.
|one Merritt coil used for the exposure was placed in one incubator and another identical Merritt coil was used for sham exposure in another identical incubator; in the exposure coils, electric currents in the two wires ran in the same direction, in sham exposure, currents ran in the opposite direction; the difference in temperature in both Merritt coils was < 0.3°C during the period of exposure
|magnetic flux density
Exposure to the magnetic field alone (group 1) had no significant effect on any parameter in comparison to the sham exposed group (group 2).
Treatment with LPS alone (group 4) led to a significantly decreased cell viability compared to sham exposed cells (group 2) and to increased amounts of DNA damage (but not significant) and nitric oxide (significance not stated).
Co-exposure to the magnetic field and LPS (group 3) resulted in significantly more DNA damage and a significantly decreased cell viability compared to a treatment with LPS alone (group 4), but nitric oxide levels were not changed.
The authors conclude that exposure to a 50 Hz magnetic field might increase DNA damage and decrease cell viability in LPS-treated macrophages, while nitric oxide levels are not influenced.