Serum plays a critical role in modulating [Ca2+]c of primary culture bone cells exposed to weak ion-resonance magnetic fields.
Primary-culture bone cells were exposed to ion-resonance (IR) magnetic fields tuned to Ca2+. Cytosolic calcium concentration, [Ca2+]c, was measured by using fura-2 during field exposure. The fields investigated were 20 muT static + muT p-p at either 15.3 or 76.6 Hz, and 0.13 mT static + either 0.5 or 1.0 mT p-p at 100 Hz. Other parameters included field orientation, culture age (2 or 5 days after plating), and the presence of serum (0 or 2%) during exposure. Total experiment time was 29.5 min: The field was applied after 2 min, and bradykinin was added as an agonist control after 22 min. The data were quantified on a single-cell basis during the 2-22 min exposure period in terms of the magnitude of the largest occurring [Ca2+]c spike normalized to local baseline. Field-exposed and control groups were characterized in terms of the percent of cells exhibiting spike magnitudes above thresholds of 100 or 66% over baseline and were compared by using Fisher's exact test. Without serum, there was little evidence that IR magnetic fields altered [Ca2+]c. However, in the presence of 2% serum, 3 of the 16 experiments exhibited significant effects at the 100% threshold. Reducing this threshold to 66% resulted in five experiments exhibiting significant effects. Most strikingly, in all of these cases, the field acted to enhance [Ca2+]c activity as opposed to suppressing [Ca2+]c activity. These findings suggest a role for serum or for constituents within serum in mediating the effects of IR magnetic fields on cells and may provide a resolution pathway to the dilemma imposed by theoretical arguments regarding the possibility of such phenomena. Possible roles of serum and future studies are discussed.
Reinbold
K A
KA
Department of Rehabilitation Medicine, University of Pennsylvania Medical Center, University of Pennsylvania, Philadelphia, 19104-6392, USA.
Pollack
S R
SR
D000818:Animals; D000831:Animals, Newborn; D001769:Blood; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003470:Culture Media; D003600:Cytosol / Q000378:metabolism / Q000528:radiation effects; D004574:Electromagnetic Fields; D007700:Kinetics; D008856:Microscopy, Fluorescence; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012886:Skull; D013997:Time Factors
D003470:Culture Media; D002118:Calcium