Effect of 50 Hz electromagnetic fields on the induction of heat-shock protein gene expression in human leukocytes.
Although evidence is controversial, exposure to environmental power-frequency magnetic fields is of public concern. Cells respond to some abnormal physiological conditions by producing cytoprotective heat-shock (or stress) proteins. In this study, we determined whether exposure to power-frequency magnetic fields in the range 0-100 microT rms either alone or concomitant with mild heating induced heat-shock protein gene expression in human leukocytes, and we compared this response to that induced by heat alone. Samples of human peripheral blood were simultaneously exposed to a range of magnetic-field amplitudes using a regimen that was designed to allow field effects to be distinguished from possible artifacts due to the position of the samples in the exposure system. Power-frequency magnetic-field exposure for 4 h at 37 degrees C had no detectable effect on expression of the genes encoding HSP27, HSP70A or HSP70B, as determined using reverse transcriptase-PCR, whereas 2 h at 42 degrees C elicited 10-, 5- and 12-fold increases, respectively, in the expression of these genes. Gene expression in cells exposed to power-frequency magnetic fields at 40 degrees C was not increased compared to cells incubated at 40 degrees C without field exposure. These findings and the extant literature suggest that power-frequency electromagnetic fields are not a universal stressor, in contrast to physical agents such as heat.
Coulton
Les A
LA
Division of Clinical Sciences (North), University of Sheffield, United Kingdom. l.coulton@sheffield.ac.uk
Harris
Paul A
PA
Barker
Anthony T
AT
Pockley
A Graham
AG
D000328:Adult; D002478:Cells, Cultured; D004307:Dose-Response Relationship, Radiation; D004574:Electromagnetic Fields; D005786:Gene Expression Regulation / Q000528:radiation effects; D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis; D006360:Heat-Shock Proteins / Q000096:biosynthesis*; D006801:Humans; D007962:Leukocytes / Q000528:radiation effects*; D008297:Male; D008875:Middle Aged; D018832:Molecular Chaperones; D009363:Neoplasm Proteins / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013696:Temperature; D013997:Time Factors
D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; C491129:HSPA7 protein, human; C057725:HSPB1 protein, human; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins