Endothelin and calcium signaling in NG108-15 neuroblastoma x glioma cells.
Endothelin (ET)-mediated Ca++ signaling in NG108-15 neuroblastoma x glioma cells was studied by measuring free intracellular Ca++ (Ca++i) levels with the fluorescent Ca++ indicator, fura-2. ET-1 produced biphasic increases in Ca++i consisting of a transient peak elevation followed by a sustained plateau phase. Both peak and plateau Ca++i responses to 5 nM ET-1 were reduced by depletion of extracellular Ca++. Peak responses were also attenuated by inhibitors of inositol phosphate metabolism, whereas plateau responses were affected by dihydropyridine Ca++ channel agonists and antagonists and by differentiation. These results suggest that peak Ca++i responses to ET-1 involve mobilization of Ca++ from inositol phosphate-sensitive intracellular stores and influx of extracellular Ca++ through nonclassical Ca++ channels, whereas plateau responses are mediated by Ca++ influx through dihydropyridine-sensitive, voltage-gated channels.
Chan
J
J
Department of Neurology, University of California, San Francisco.
Greenberg
D A
DA
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002454:Cell Differentiation; D016232:Endothelins / Q000494:pharmacology*; D000431:Ethanol / Q000494:pharmacology; D005910:Glioma / Q000378:metabolism; D051379:Mice; D009447:Neuroblastoma / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D011493:Protein Kinase C / Q000502:physiology; D013696:Temperature; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D016232:Endothelins; D000431:Ethanol; D011189:Potassium Chloride; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium