Purpose: This study aimed to determine whether Terrestrial Trunked Radio (TETRA) fields can affect intracellular calcium signalling in excitable cells.
Materials and methods: Intracellular calcium concentration ([Ca(2 +) ](i)) was measured in cultured rat cerebellar granule cells and cardiac myocytes during exposure to TETRA fields (380.8875 MHz pulse modulated at 17.6 Hz, 25% duty cycle). [Ca(2 +) ](i) was measured as fura-PE3, fluo-3 or fluo-4 fluorescence by digital image analysis.
Results: Granule cells exposed at specific absorption rates (SARs) of 5, 10, 20, 50 or 400 mW x kg(-1) showed no significant changes in resting [Ca(2 +) ](i). Increases in [Ca(2 +) ](i) in response to potassium-induced depolarization were significantly different from sham controls in TETRA-exposed cells, but the majority of the difference was attributable to initial biological variation between cell cultures. No difference was found between fura-PE3 (UV excitation) and fluo-3 (visible light excitation) measurements in these cells. Exposure to TETRA (50 or 400 mW x kg(-1)) had no significant effect on either the rate or amplitude of spontaneous Ca(2 +) transients in cardiac myocytes. The cells showed normal responses to salbutamol (50 microM) and acetylcholine (10 microM).
Conclusions: Overall, these results showed no evidence of any consistent or biologically relevant effect of TETRA fields on [Ca(2 + )](i) in granule cells and cardiac myocytes at any of the SAR tested.