Effects of time-varying electromagnetic fields on K+ (Rb+) fluxes and surface charge of HeLa cells.
The magnetic flux density was varied intermittently from 0.35 to 1.77T and from 0.07 to 1.54 or 1.77T by manual and automatic switchings, respectively, of the power source of an electromagnet. The durations of the "switching-on time" and "-off time" were varied but kept equal. An electric eddy current induced in the culture medium by changes in the magnetic flux density was simulated. When the durations were shorter than 10s, ouabain-sensitive Rb+ influx (active K+ influx) into cultured HeLa cells was significantly inhibited, but the ouabain-insensitive Rb+ influx (passive K+ influx) was not influenced significantly. Inhibition of active Rb+ influx increased with time during exposure for 2 h. Conversely, K+ efflux from the cells was significantly stimulated by the exposure. Microfluorometric examinations of cells loaded with the fluorescent pH indicator 4-heptadecyl-7-hydroxycoumarin (6 microM) and the membrane potential indicator diS-C3-(5) (1 microM) suggested increase in the negative charge on the cell surface during exposure. The observed changes in the K+ (Rb+) fluxes would be related to change in the electric properties of the cell surface caused by exposure to intermittent electromagnetic fields.
Yamaguchi
H
H
Department of Physiology, School of Medicine, University of Tokushima, Japan.
Ikehara
T
T
Hosokawa
K
K
Soda
A
A
Shono
M
M
Miyamoto
H
H
Kinouchi
Y
Y
Tasaka
T
T
D002462:Cell Membrane / Q000378:metabolism*; D004574:Electromagnetic Fields; D006367:HeLa Cells; D006801:Humans; D008564:Membrane Potentials / Q000502:physiology; D008856:Microscopy, Fluorescence; D011188:Potassium / Q000378:metabolism*; D012413:Rubidium / Q000378:metabolism*; D013499:Surface Properties; D013696:Temperature
D012413:Rubidium; D011188:Potassium