title: Prolonged Ca2+ transients in ATP-stimulated endothelial cells exposed to 50 Hz electric fields.
abstract: Human umbilical vein endothelial cells were exposed to sinusoidal electric fields of 0.3 or 30 kV/m, 50 Hz, for 24 h. Changes in intracellular calcium concentration ([Ca(2+)](i)) induced by ATP-stimulation in the absence of extracellular Ca(2+) were observed in individual cells. No differences were observed between the exposure and sham-exposure groups in [Ca(2+)](i) resting level before ATP-stimulation, or in the [Ca(2+)](i) peak levels induced by stimulation. However, the duration of the initial transients in [Ca(2+)](i) following an ATP stimulus was significantly prolonged by exposure to a 30 kV/m field. The inositol trisphosphate receptor inhibitor, xestospongin C, inhibited the ATP-induced elevation in [Ca(2+)](i) in both the exposure and sham-exposure groups. The ATP-receptor P2Y appeared to play an important role in the increase of [Ca(2+)](i). The present results suggest that an extremely low-frequency electric field affects the function of vascular endothelial cells by a mechanism involving activation of P2Y.
authors.affiliation: 1st Department of Anatomy, National Defense Medical College, Namiki 3-2, Tokorozawa, Saitama 359-8513, Japan. kunito@cc.ndmc.ac.jp
authors.forename: Kunihito
authors.initials: K
authors.lastname: Takahashi
authors.forename: Fuyuki
authors.initials: F
authors.lastname: Doge
authors.forename: Masahiko
authors.initials: M
authors.lastname: Yoshioka
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels; D020013:Calcium Signaling; D004574:Electromagnetic Fields; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016257:Fura-2; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors; D047028:Macrocyclic Compounds; D010080:Oxazoles / Q000494:pharmacology; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D013237:Stereoisomerism; D014471:Umbilical Veins / Q000166:cytology
chemical_list: D015220:Calcium Channels; D004791:Enzyme Inhibitors; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D047028:Macrocyclic Compounds; D010080:Oxazoles; D018160:Receptors, Cytoplasmic and Nuclear; D018048:Receptors, Purinergic P2; C108644:xestospongin A; D000255:Adenosine Triphosphate; D002118:Calcium; D016257:Fura-2