Extremely low frequency electromagnetic fields and heat shock can increasemicrovesicle motility in astrocytes

The effect of extremely low frequency electromagnetic fields (EMF) on micro vesicles was examined in rat astrocytes by video-enhanced microscopy in com bination with a perfusable cell chamber. The EMF effect was compared with t he effect of heat shock (HS) and with a combination of them both. The veloc ity of microvesicles was measured using image processing software (NIH Scio n image 1.61). After exposure of astrocytes to EMF (50Hz, 100 muT, 1 h), th e velocity of microvesicles in astrocytes increased from 0.32 +/- 0.03 mum/ s (n = 120, 95% CI) in the untreated control group to 0.41 +/- 0.03 mum/s ( n = 175, 95% CI). Fifteen minutes after HS (45 degreesC. 10 min) the microv esicles showed a velocity of 0.56 +/- 0.03 mum/s (n = 125, 95% CI). Combina tion of HS and EMF led to an increase in velocity up to 0.54 +/- 0.03 mum/s (n = 110, 95% CI). No significant difference between HS and HS + EMF was f ound. Compared to the untreated control group. the increased microvesicle v elocity of the exposed cells might be a stress response of the cell. It is possibly a sign of intensified intracellular traffic required to adjust the metabolic needs. Bioelectromagnetics 22:71-78. 2001. (C) 2001 Wiley-Liss, Inc.