Intracellular Ca2+ microdomain-triggered exocytosis in neuroendocrine cells.
Colocalization of voltage-gated Ca2+ channels and exocytotic sites at the active zones of nerve terminals underlies 'synchronous' action potential discharge and synaptic vesicle exocytosis, thus allowing fast interneuronal signalling. Such a demand for a rapid release is not expected in neuroendocrine cells whose secretory products act throughout the entire organism. Nevertheless, by using evanescent field imaging of near-membrane Ca2+ concentrations and fluorescently labelled vesicles, Becherer et al. have recently reported exocytosis of individual large dense-core vesicles triggered by Ca2+ microdomains formed around clusters of open L-type Ca2+ channels in chromaffin cells from the adrenal medulla. This finding, besides illustrating the power of new microscopy imaging techniques, directly demonstrates in neuroendocrine cells a functional interaction between Ca2+ channels and secretory vesicles very much reminiscent of that in neurons.
Olivos Oré
Luis
L
Departmentof Toxicology and Pharmacology, School of Veterinary Sciences, Complutense University, Madrid, Spain.
Artalejo
Antonio R
AR
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000502:physiology; D019439:Chromaffin Cells / Q000502:physiology*; D005089:Exocytosis / Q000502:physiology*; D007424:Intracellular Fluid / Q000502:physiology; D008856:Microscopy, Fluorescence / Q000379:methods; D009490:Neurosecretory Systems / Q000166:cytology* / Q000378:metabolism; D017729:Presynaptic Terminals / Q000378:metabolism
D015220:Calcium Channels; D002118:Calcium