%0 Journal Article %A Valérie De Crescenzo %A Ronghua ZhuGe %A Cristina Velázquez-Marrero %A Lawrence M. Lifshitz %A Edward Custer %A Jeffrey Carmichael %A F. Anthony Lai %A Richard A. Tuft %A Kevin E. Fogarty %A José R. Lemos %A John V. Walsh, Jr %T Ca2+ Syntillas, Miniature Ca2+ Release Events in Terminals of Hypothalamic Neurons, Are Increased in Frequency by Depolarization in the Absence of Ca2+ Influx %D 2004 %R 10.1523/JNEUROSCI.4286-03.2004 %J The Journal of Neuroscience %P 1226-1235 %V 24 %N 5 %X 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 ∼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. %U https://www.jneurosci.org/content/jneuro/24/5/1226.full.pdf