To study the effects of 50 Hz extremely low frequency electric fields on intracellular Ca2+ peak levels and on the duration of Ca2+ transients using Fluo3 fluorescence in individual human umbilical vein endothelial cells stimulated by ATP.
To ascertain whether the influence of the electric fields on the Ca2+ signal was related to the release of Ca2+ from intracellular stores, the effects of an inositol triphosphate receptor inhibitor (xestospongin C, 10 µM) were also investigated.
|electric field strength||30 mV/m||-||-||-||-|
Alterations in intracellular calcium concentration induced by ATP-stimulation in the absence of extracellular Ca2+ were revealed in individual cells. No differences were found between the exposure and sham-exposure groups in intracellular calcium concentration resting level before ATP-stimulation, or in the intracellular calcium concentration peak levels induced by stimulation. However, the duration of the initial transients in intracellular calcium concentration following an ATP stimulus was significantly prolonged by exposure to a 30 kV/m field.
The inositol trisphosphate receptor inhibitor inhibited the ATP-induced elevation in intracellular calcium concentration in both the exposure and sham exposure groups. The ATP-receptor P2Y appeared to play an important role in the increase of intracellular calcium concentration.
The data indicate that an extremely low frequency electric field affects the function of vascular endothelial cells by a mechanism involving activation of P2Y.