Intracellular Ca2+ microdomain-triggered exocytosis in neuroendocrine cells

Trends Neurosci. 2004 Mar;27(3):113-5. doi: 10.1016/j.tins.2004.01.001.

Abstract

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.

MeSH terms

  • Action Potentials / physiology
  • Animals
  • Calcium / physiology*
  • Calcium Channels / physiology
  • Chromaffin Cells / physiology*
  • Exocytosis / physiology*
  • Intracellular Fluid / physiology
  • Microscopy, Fluorescence / methods
  • Neurosecretory Systems / cytology*
  • Neurosecretory Systems / metabolism
  • Presynaptic Terminals / metabolism

Substances

  • Calcium Channels
  • Calcium