title: Ca2+ syntillas, miniature Ca2+ release events in terminals of hypothalamic neurons, are increased in frequency by depolarization in the absence of Ca2+ influx.
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.
authors.affiliation: Department of Physiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.
authors.forename: Valérie
authors.initials: V
authors.lastname: De Crescenzo
authors.forename: Ronghua
authors.initials: R
authors.lastname: ZhuGe
authors.forename: Cristina
authors.initials: C
authors.lastname: Velázquez-Marrero
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: Lifshitz
authors.forename: Edward
authors.initials: E
authors.lastname: Custer
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Carmichael
authors.forename: F Anthony
authors.initials: FA
authors.lastname: Lai
authors.forename: Richard A
authors.initials: RA
authors.lastname: Tuft
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Fogarty
authors.forename: José R
authors.initials: JR
authors.lastname: Lemos
authors.forename: John V
authors.initials: JV
authors.lastname: Walsh
mesh_terms: D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D007031:Hypothalamus / Q000737:chemistry / Q000166:cytology*; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D013347:Subcellular Fractions / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism
chemical_list: D019837:Ryanodine Receptor Calcium Release Channel; D002110:Caffeine; D002118:Calcium