Dissection of three Ca2+-dependent steps leading to secretion in chromaffin cells from mouse adrenal slices

Neuron. 2000 Nov;28(2):537-45. doi: 10.1016/s0896-6273(00)00131-8.


In neurosecretory cells, intracellular Ca2+ ([Ca2+]i) not only acts as the trigger for secretion but also regulates earlier steps in the secretory pathway. Here, a novel approach was developed to control [Ca2+]i over a broad concentration range, which allowed the quantification of three distinct actions of [Ca2+]i on large dense-core vesicle (LDCV) fusion in chromaffin cells from mouse adrenal slices. Basal [Ca2+]i regulated the transfer of vesicles toward a slowly releasable state, whereas further maturation to the readily releasable state was Ca2+ independent. [Ca2+]i levels above 3 microM triggered exocytosis of all readily and slowly releasable vesicles in two parallel, kinetically distinct fusion reactions. In a molecular context, these results suggest that Ca2+ acts both before and after trans-SNARE complex formation to regulate fusion competence and fusion kinetics of LDCVs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenal Glands / cytology
  • Adrenal Glands / metabolism*
  • Animals
  • Calcium / metabolism*
  • Calcium / pharmacology
  • Cells, Cultured
  • Chromaffin Cells / cytology
  • Chromaffin Cells / metabolism*
  • Egtazic Acid / analogs & derivatives*
  • Egtazic Acid / metabolism
  • Egtazic Acid / pharmacology
  • Egtazic Acid / radiation effects
  • Exocytosis / drug effects
  • Exocytosis / physiology*
  • Fluorescent Dyes
  • In Vitro Techniques
  • Membrane Fusion / drug effects
  • Membrane Fusion / physiology
  • Membrane Proteins / metabolism
  • Mice
  • Models, Neurological
  • Photolysis
  • Reaction Time / drug effects
  • Reaction Time / physiology
  • SNARE Proteins
  • Secretory Vesicles / drug effects
  • Secretory Vesicles / metabolism
  • Vesicular Transport Proteins*


  • Fluorescent Dyes
  • Membrane Proteins
  • SNARE Proteins
  • Vesicular Transport Proteins
  • 2-nitrophenyl-EGTA
  • Egtazic Acid
  • Calcium