Extracellular calcium sensing by glial cells: low extracellular calcium induces intracellular calcium release and intercellular signaling.
Glial cells in primary mixed cultures or purified astrocyte cultures from mouse cortex respond to reduced extracellular calcium concentration ([Ca2+]e) with increases in intracellular calcium concentration ([Ca2+]i) that include single-cell Ca2+ oscillations and propagated intercellular Ca2+ waves. The rate and pattern of propagation of low [Ca2+]e-induced intercellular Ca2+ waves are altered by rapid perfusion of the extracellular medium, suggesting the involvement of an extracellular messenger in Ca2+ wave propagation. The low [Ca2+]e-induced Ca2+ response is abolished by thapsigargin and by the phospholipase antagonist U73122. The low [Ca2+]e-induced response is also blocked by replacement of extracellular Ca2+ with Ba2+, Zn2+, or Ni2+, and by 100 microM La3+. Glial cells in lowered [Ca2+]e (0.1-0.5 mM) show an increased [Ca2+]i response to bath application of ATP, whereas glial cells in increased [Ca2+]e (10-15 mM) show a decreased [Ca2+]i response to ATP. These results show that glial cells possess a mechanism for coupling between [Ca2+]e and the release of Ca2+ from intracellular stores. This mechanism may be involved in glial responses to the extracellular environment and may be important in pathological conditions associated with low extracellular Ca2+ such as seizures or ischemia.
Zanotti
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S
Department of Neurology, UCLA School of Medicine, Los Angeles, California 90095, USA.
Charles
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A
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000008:administration & dosage / Q000378:metabolism* / Q000494:pharmacology*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D004963:Estrenes / Q000494:pharmacology; D051379:Mice; D009457:Neuroglia / Q000187:drug effects* / Q000378:metabolism*; D010507:Periodicity; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010740:Phospholipases / Q000037:antagonists & inhibitors; D011760:Pyrrolidinones / Q000494:pharmacology; D013498:Suramin / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology
D004963:Estrenes; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D013498:Suramin; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D010740:Phospholipases; D002118:Calcium