Luciferase activity and synthesis of Hsp70 and Hsp90 are insensitive to 50Hz electromagnetic fields

The activity of luciferase expressed in transfected 34i cells has been monitored under 50Hz EMF and heat shock. While heat shock decreased the luciferase activity, short exposure to EMFs did not, the luciferase expressed in cells exposed to EMFs at 300-3000 microT showing the same activity as that of control cells. To further analyse whether EMF and thermal stress display similar effects, the relative rate of Hsp90 and Hsp70 synthesis was investigated. Hsp90 and Hsp70 synthesis, while induced by a short thermal stress, was not increased by EMF exposure. These results, contrary to previously proposed similarities between thermal stress and EMF effects at a cellular level, indicate that protein denaturation and misfolding caused by thermal stress and responsible both for a loss of luciferase activity and for an induction of Hsp, are not necessarily induced by exposure to EMFs.