Abstract
We measured the amount of AP sites (Apurinic/apyrimidinic sites) in human glioma A172 cells to investigate the effect of extremely low frequency electromagnetic fields (ELF-EMF) at 5 mT. The cells were exposed to ELF-EMF alone, H2O2 (hydrogen peroxide) alone, or ELF-EMF with H2O2 in medium. The duration of exposure was 2, 4, 8, 16 and 24 hours. After the exposure, the cells were collected by cell-scraper, washed with PBS 3 times, and then we extracted DNA from the cells. After isolating DNA, ARP (Aldehyde Reactive Probe) reagents were added to DNA. Then, AP sites were tagged with biotin residues, which could be quantified using avidin-biotin assay, followed by a colorimetric detection of 450 nm. The number of AP sites were determined by calibration curve of 0∼40ARP/105 bp in standard DNAs. There was no difference in the number of AP sites between ELF-EMF exposed cells and sham control. The level of AP sites was increased H2O2 treatment alone. The combined treatment of ELF-EMF and H2O2 increased AP site levels on 8, 16 and 24 h exposure compared with H2O2 treatment alone. In this study, the exposure of ELF-EMF alone may have no effect to produce AP site. However, AP sites induced by H2O2 might be enhanced by ELF-EMF exposure.
