Ca2+ syntillas, miniature Ca2+ release events in terminals of hypothalamic neurons, are increased in frequency by depolarization in the absence of Ca2+ influx
De Crescenzo, Valerie ; ZhuGe, Ronghua ; Velazquez-Marrero, Cristina M. ; Lifshitz, Lawrence M. ; Custer, Edward E. ; Carmichael, Jeffrey ; Lai, F. Anthony ; Tuft, Richard A. ; Fogarty, Kevin E. ; Lemos, Jose R. ... show 1 more
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Abstract
Localized, brief Ca2+ transients (Ca2+ syntillas) caused by release from intracellular stores were found in isolated nerve terminals from magnocellular hypothalamic neurons and examined quantitatively using a signal mass approach to Ca2+ imaging. Ca2+ syntillas (scintilla, L., spark, from a synaptic structure, a nerve terminal) are caused by release of approximately 250,000 Ca ions on average by a Ca2+ flux lasting on the order of tens of milliseconds and occur spontaneously at a membrane potential of -80 mV. Syntillas are unaffected by removal of extracellular Ca2+, are mediated by ryanodine receptors (RyRs) and are increased in frequency, in the absence of extracellular Ca2+, by physiological levels of depolarization. This represents the first direct demonstration of mobilization of Ca2+ from intracellular stores in neurons by depolarization without Ca2+ influx. The regulation of syntillas by depolarization provides a new link between neuronal activity and cytosolic [Ca2+] in nerve terminals.
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J Neurosci. 2004 Feb 4;24(5):1226-35. Link to article on publisher's site
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Co-author Cristina M. Velazquez-Marrero is a student in the Neuroscience program in the Graduate School of Biomedical Sciences (GSBS) at UMass Medical School.