Changes in cellular proteins due to environmental non-ionizing radiation. I. Heat-shock proteins

This paper describes the effect of weak microwave fields on the amounts of heat-shock proteins in cell cultures at various temperatures. The field was generated by signal simulation of the Global System for Mobil e communications (GSM) of 950 Mhz, used in portable phones. Transformed hum an epithelial amnion (AMA) cells, growing on glass coverslips, were exposed in a transverse electromagnetic (TEM) cell to a microwave field, generatin g a specific absorption rate (SAR) of 2.1 mW.kg(-1) in the cells. Exposure temperatures were 35, 37, and 40 +/-0.1 degreesC, respectively, and the exp osure time was 20 min. The heat-shock proteins Hsp-70 and Hsp-27 were detected by immunofluorescen ce. Higher amounts of Hsp-70 were present in the cells exposed at 35 and 37 degreesC than in the sham-exposed cells. These effects can be considered to be athermal, since the field strength wa s much lower than the safety standard for absence of heat generation by mic rowave fields. There was no significant response in the case of Hsp-27.