Colocalization of active KCa channels and Ca2+ channels within Ca2+ domains in helix neurons.
Large conductance Ca(2+)-activated K+ channels (KCa channels) have to be colocalized with Ca2+ channels to be involved in nerve cell firing regulation. KCa channels were detected in cell-attached patches performed in voltage-clamped Helix neurons. This technique allowed Ca2+ entry to occur either within or around the patch. We observed that the submembrane Ca2+ diffusion was sufficiently limited to prevent the KCa channels from being opened by remote Ca2+ entry. The KCa channels located in areas devoid of Ca2+ channels remained quiescent during cell firing. These crypto channels were detected following either patch excision or intracellular Ca2+ injection. These data provide direct evidence for the existence of functional Ca2+ domains in a nonspecialized neural membrane.
Laboratoire de Neurobiologie, CNRS 31, Marseille, France.
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D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D015220:Calcium Channels / Q000378:metabolism* / Q000502:physiology; D004058:Diffusion; D004594:Electrophysiology; D006372:Helix, Snails / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D014018:Tissue Distribution
D015220:Calcium Channels; D002118:Calcium