Pulsed electromagnetic fields affect the intracellular calcium concentrations in human astrocytoma cells

Experiments assessed whether long term exposure to 50 Hz pulsed electromagnetic fields with a peak magnetic field of 3 mT can alter the dynamics of intracellular calcium in human astrocytoma U-373 MG cells. Pretreatment of cells with 1.2 μM substance P significantly increased the [Ca2+]i. The same effect was also observed when [Ca2+]i was evaluated in the presence of 20 mM caffeine. After exposure to electromagnetic fields the basal [Ca2+]i levels increased significantly from 143 ± 46 nM to 278 ± 125 nM. The increase was also evident after caffeine addition, but in cells treated with substance P and substance P + caffeine we observed a [Ca2+]i decrease after exposure. When we substituted calcium-free medium for normal medium immediately before the [Ca2+]i measurements, the [Ca2+]i was similar to that measured in the presence of Ca2+. In this case, after EMFs exposure of cells treated with substance P, the [Ca2+]i, measured without and with addition of caffeine, declined from 824 ± 425 to 38 ± 13 nM and from 1369 ± 700 to 11 ± 4 nM, respectively, indicating that electromagnetic fields act either on intracellular Ca2+ stores or on the plasma membrane. Moreover the electromagnetic fields that affected [Ca2+]i did not cause cell proliferation or cell death and the proliferation indexes remained unchanged after exposure. © 2001 Wiley-Liss, Inc.