Electric field-induced changes in agonist-stimulated calcium fluxes of human HL-60 leukemia cells

• Published in: Bioelectromagnetics Vol. 19; no. 6; pp. 366 - 376
• Main Authors: Kim, Yuri V., Conover, David L., Lotz, W. Gregory, Cleary, Stephen F.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 1998
• Subjects: 60 Hz electric field; Adenosine Triphosphate - metabolism; Adenosine Triphosphate - pharmacology; Calcium - metabolism; Calcium Channels - drug effects; Calcium Channels - physiology; Calcium Channels - radiation effects; Cell Membrane - physiology; Cell Membrane - radiation effects; Electromagnetic Fields; Histamine - pharmacology; histamine receptor; HL-60 Cells - radiation effects; Humans; intracellular free calcium concentration; purinergic receptor; receptor-operated ion channels
• ISSN: 0197-8462; 1521-186X
• 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 μM ATP or by 100 μM 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 μM) 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 μM). 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. Bioelectromagnetics 19:366–376, 1998. © 1998 Wiley‐Liss, Inc.