The effect of pulsed electromagnetic fields on the physiologic behaviour of a human astrocytoma cell line

We evaluated the effects of 50 Hz pulsed electromagnetic fields (EMFs) with a peak magnetic field of 3 mT on human astrocytoma cells. Our results clearly demonstrate that, after the cells were exposed to EMFs for 24 h, the basal [Ca2+](i) levels increased significantly from 124 +/- 51 nM to 200 +/- 79 nM. Pretreatment of the cells with 1.2 muM substance P increased the [Ca2+](i) to 555 +/- 278 nM, while EMF exposure caused a significant drop in [Ca2+](i) to 327 +/- 146 nM. The overall effect of EMFs probably depends on the prevailing Ca2+ conditions of the cells. After exposure, the proliferative responses of both normal and substance P-pretreated cells increased slightly from 1.03 to 1.07 and 1.04 to 1.06, respectively. U-373 MG cells spontaneously released about 10 pg/ml of interleukin-6 which was significantly increased after the addition of substance P. Moreover, immediately after EMF exposure and 24 h thereafter, the interleukin-6 levels were more elevated (about 40%) than in controls. On the whole, our data suggest that, by changing the properties of cell membranes, EMFs can influence Ca2+ transport processes and hence Ca2+ homeostasis. The increased levels of interleukin-6 after 24 h of EMF exposure may confirm the complex connection between Ca2+ levels, substance P and the cytokine network. (C) 2000 Elsevier Science B.V. All rights reserved.