Cellular and molecular responses to power-frequency electromagnetic fields.

本研究研究了在高强度极低频（ELF）磁场作用下应激蛋白即热休克蛋白基因表达的变化，并作为阳性对照研究热处理的影响。此外，我们还研究了磁场对热休克蛋白基因表达在磁场和热处理联合处理下的修饰作用。热休克蛋白是一种典型的热休克蛋白，它能对包括热休克在内的多种应激发生反应，并进行短暂表达。Goodman等人（1997）报道了极低频磁场暴露对ESP70的诱导作用，但获得了μT水平的数据，并发表了否定的反驳。在本研究中，我们使用Goodman等人使用的人白血病源性细胞（HL60）研究了暴露于高磁场强度的极低频磁场是否会对热休克蛋白的诱导产生影响。50mt极低频磁场作用24h后，未观察到HSP70蛋白的表达。作为正对照，我们研究了热处理的影响。此外，我们还研究了磁场对极低频磁场和热处理联合处理下热休克蛋白基因表达的修饰作用。轻度热休克（40 ~ 42℃）诱导HL60细胞表达HSP70蛋白。该热处理与50 mT极低频磁场联合处理后，HSP70蛋白表达水平低于单独热休克处理，说明极低频磁场抑制了HSP70蛋白表达。结果表明，高强度的极低频磁场增强了热休克诱导的HSP70表达的负反馈作用，抑制了HSP70的表达。

We investigated the change in gene expression of the stress protein, i.e., the heat shock protein in this study, under a high intensity of extremely low frequency (ELF) magnet field, and as a positive control, we investigated the effect of heat processing. In addition, we also studied a modifying effect of the magnetic field on gene expression of the heat shock protein under treatment of combination of the magnetic field and heat processing.1. The study on the heat shock protein was performed using HSP70, a typical heat shock protein, which reacts to numerous stresses including heat shock and expresses transiently. Goodman et al. (1997) reported ESP70 induction by ELF magnetic field exposure, however, the data at the level of μT were obtained and negative counterarguments were published. In this study, we investigated whether the exposure to a high magnetic intensity of ELF magnet field produces an effect on induction of the heat shock protein or not using human leukemia-derived cells (HL60) that Goodman et al. used. No induction of HSP70 protein expression was observed 24 hours after exposure to the 50 mT ELF magnetic field.2. As a positive control, we investigated the effect of heat processing. In addition, we also studied a modifying effect of the magnetic field on gene expression of the heat shock protein under treatment of combination of the ELF magnetic field and heat processing. Under a mild heat shock (40 - 42 ℃), induction of HSP70 protein expression was observed in HL60 cells. After combined treatment of this heat processing and exposure to the 50 mT ELF magnetic field, the level of HSP70 protein expression was lower than that under treatment of heat shock alone, which indicated that the ELF magnetic field inhibited the HSP70 protein expression. These results suggested that a high intensity of ELF magnetic field exaggerated the negative feedback action against the HSP70 expression induced by the heat shock and inhibited the HSP70 expression.