Kim Y V, Conover D L, Lotz W G, Cleary S F
Division of Biomedical and Behavioral Science, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226, USA.
Bioelectromagnetics. 1998;19(6):366-76. doi: 10.1002/(sici)1521-186x(1998)19:6<366::aid-bem4>3.0.co;2-#.
The mechanism of biological effects of extremely-low-frequency electric and magnetic fields may involve induced changes of Ca2+ transport through plasma membrane ion channels. In this study we investigated the effects of externally applied, low-intensity 60 Hz electric (E) fields (0.5 V/m, current density 0.8 A/m2) on the agonist-induced Ca2+ fluxes of HL-60 leukemia cells. The suspensions of HL-60 cells received E-field or sham exposure for 60 min and were simultaneously stimulated either by 1 microM ATP or by 100 microM histamine or were not stimulated at all. After E-field or sham exposure, the responses of the intracellular calcium levels of the cells to different concentrations of ATP (0.2-100 microM) were assessed. Compared with control cells, exposure of ATP-activated cells to an E-field resulted in a 20-30% decrease in the magnitude of [Ca2+]i elevation induced by a low concentration of ATP (<1 microM). In contrast, exposure of histamine-activated HL-60 cells resulted in a 20-40% increase of ATP-induced elevation of [Ca2+]i. E-field exposure had no effect on non-activated cells. Kinetic analysis of concentration-response plots also showed that compared with control cells, exposure to the E-field resulted in increases of the Michaelis constant, Km, value in ATP-treated cells and of the maximal [Ca2+]i peak rise in histamine-treated HL-60 cells. The observed effects were reversible, indicating the absence of permanent structural damages induced by acute 60 min exposure to electric fields. These results demonstrate that low-intensity electric fields can alter calcium distribution in cells, most probably due to the effect on receptor-operated Ca2+ and/or ion channels.
极低频电场和磁场的生物效应机制可能涉及通过质膜离子通道诱导的Ca2+转运变化。在本研究中，我们研究了外部施加的低强度60 Hz电场（E场）（0.5 V/m，电流密度0.8 A/m2）对HL-60白血病细胞激动剂诱导的Ca2+通量的影响。HL-60细胞悬液接受E场或假暴露60分钟，并同时用1 microM ATP或100 microM组胺刺激，或根本不刺激。在E场或假暴露后，评估细胞内钙水平对不同浓度ATP（0.2 - 100 microM）的反应。与对照细胞相比，将ATP激活的细胞暴露于E场导致低浓度ATP（<1 microM）诱导的[Ca2+]i升高幅度降低20 - 30%。相反，组胺激活的HL-60细胞暴露导致ATP诱导的[Ca2+]i升高增加20 - 40%。E场暴露对未激活的细胞没有影响。浓度 - 反应曲线的动力学分析还表明，与对照细胞相比，暴露于E场导致ATP处理细胞中的米氏常数Km值增加，以及组胺处理的HL-60细胞中最大[Ca2+]i峰值升高。观察到的效应是可逆的，表明急性60分钟暴露于电场不会引起永久性结构损伤。这些结果表明，低强度电场可以改变细胞内的钙分布，很可能是由于对受体操纵的Ca2+和/或离子通道的影响。
