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Calcium homeostasis of isolated heart muscle cells exposed to pulsed high‐frequency electromagnetic fields
Author(s) -
Wolke S.,
Neibig U.,
Elsner R.,
Gollnick F.,
Meyer R.
Publication year - 1996
Publication title -
bioelectromagnetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.435
H-Index - 81
eISSN - 1521-186X
pISSN - 0197-8462
DOI - 10.1002/(sici)1521-186x(1996)17:2<144::aid-bem9>3.0.co;2-3
Subject(s) - duty cycle , calcium , pulse (music) , depolarization , square wave , chemistry , biophysics , stimulation , myocyte , materials science , nuclear magnetic resonance , physics , optics , medicine , biology , voltage , organic chemistry , quantum mechanics , detector
The intracellular calcium concentration ([Ca 2+ ] i ) of isolated ventricular cardiac myocytes of the guinea pig was measured during the application of pulsed high‐frequency electromagnetic fields. The high‐frequency fields were applied in a transverse electromagnetic cell designed to allow microscopic observation of the myocytes during the presence of the high‐frequency fields. The [Ca 2+ ] i was measured as fura‐2 fluorescence by means of digital image analysis. Both the carrier frequency and the square‐wave pulse‐modulation pattern were varied during the experiments (carrier frequencies: 900, 1,300, and 1,800 MHz pulse modulated at 217 Hz with 14% duty cycle; pulsation pattern at 900 MHz: continuous wave, 16 Hz, and 50 Hz modulation with 50% duty cycle and 30 kHz modulation with 80% duty cycle). The mean specific absorption rate (SAR) values in the solution were within one order of magnitude of 1 mW/kg. They varied depending on the applied carrier frequency and pulse pattern. The experiments were designed in three phases: 500 s of sham exposure, followed by 500 s of field exposure, then chemical stimulation without field. The chemical stimulation (K + ‐depolarization) indicated the viability of the cells. The K + depolarization yielded a significant increase in [Ca 2+ ] i . Significant differences between sham exposure and high‐frequency field exposure were not found except when a very small but statistically significant difference was detected in the case of 900 MHz/50 Hz. However, this small difference was not regarded as a relevant effect of the exposure. © 1996 Wiley‐Liss, Inc.