Electric field-induced changes in agonist-stimulated calcium fluxes of human HL-60 leukemia cells
✍ Scribed by Yuri V. Kim; David L. Conover; W. Gregory Lotz; Stephen F. Cleary
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 245 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0197-8462
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✦ Synopsis
The mechanism of biological effects of extremely-low-frequency electric and magnetic fields may involve induced changes of Ca 2/ 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/m 2 ) on the agonist-induced Ca 2/ 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 mM ATP or by 100 mM 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 mM) were assessed. Compared with control cells, exposure of ATP-activated cells to an Efield resulted in a 20 -30% decrease in the magnitude of [Ca 2/ ] i elevation induced by a low concentration of ATP (õ1 mM). In contrast, exposure of histamine-activated HL-60 cells resulted in a 20 -40% increase of ATP-induced elevation of [Ca 2/ ] 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, K m , value in ATP-treated cells and of the maximal [Ca 2/ ] 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 Ca 2/ and/or ion channels.