Time-varying magnetic fields increase cytosolic free Ca2+ in HL-60 cells.
Electromagnetic fields have been reported to cause a variety of biological effects. It has been hypothesized that many of these phenomena are mediated by a primary effect on the concentration of cytosolic free calcium ([Ca2+]i). We investigated the effects of exposure to electromagnetic fields on [Ca2+]i in HL-60 cells using the Ca2(+)-sensitive fluorescent indicator indo-1. Indo-1-loaded cell samples were exposed to a radiofrequency electromagnetic field, a static magnetic field, and a time-varying magnetic field, which were generated by a magnetic resonance imaging (MRI) unit. We found that a 23-min exposure to all three fields, in combination, induced a significant increase in [Ca2+]i of 31 +/- 8 (SE) nM (P less than 0.01, n = 13) from a basal level of 121 +/- 8 nM. Also, cells exposed to only the time-varying magnetic field had a mean [Ca2+]i that was 34 +/- 10 nM (P less than 0.01, n = 11) higher than parallel control samples. Separate exposure to the radio-frequency (6.25 MHz) or static field (0.15 T) had no detectable effects. These results demonstrate that time-varying magnetic fields alter [Ca2+]i and suggest that at least some of the reported biological effects of time-varying magnetic fields may arise from elevation of [Ca2+]i.
Carson
J J
JJ
Lawson Research Institute, St. Joseph's Health Centre, London, Ontario, Canada.
Prato
F S
FS
Drost
D J
DJ
Diesbourg
L D
LD
Dixon
S J
SJ
D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism / Q000528:radiation effects; D005456:Fluorescent Dyes; D006801:Humans; D007211:Indoles; D007700:Kinetics; D015473:Leukemia, Promyelocytic, Acute; D008279:Magnetic Resonance Imaging; D008280:Magnetics; D011846:Radio Waves; D013050:Spectrometry, Fluorescence; D013997:Time Factors
D005456:Fluorescent Dyes; D007211:Indoles; C048960:indo-1; D002118:Calcium