AJP - Cell Physiology, Vol 259, Issue 4 C687-C692, Copyright © 1990 by American Physiological Society
Time-varying magnetic fields increase cytosolic free Ca2+ in HL-60 cells
J. J. Carson, F. S. Prato, D. J. Drost, L. D. Diesbourg and S. J. Dixon
Lawson Research Institute, St. Joseph's Health Centre, London, Ontario, Canada.
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.
