Three types of Ca2+ channel trigger secretion with different efficacies in chromaffin cells

Nature. 1994 Jan 6;367(6458):72-6. doi: 10.1038/367072a0.


To determine whether the different types of Ca2+ channels present in the same secretory cell contribute equally to secretion, we used chromaffin cells to analyse the coupling between three distinct types of Ca2+ channel and exocytosis. These are omega-conotoxin-GVIA-sensitive N-type channels, omega-agatoxin-IVA-sensitive P-type Ca2+ channels and dihydropyridine-sensitive facilitation Ca2+ channels, which are normally quiescent but are activated by depolarizing pre-pulses, repetitive depolarizations to physiological potentials, or agents that raise cyclic AMP. We have simultaneously monitored changes in capacitance as an assay of catecholamine secretion, and Ca2+ currents. Although all three types of Ca2+ channel trigger secretion individually, facilitation channels produce much greater secretion for a given size of Ca2+ current, indicating that they are coupled more efficiently to exocytosis. These results indicate that facilitation Ca2+ channels may be physically nearer vesicle release sites. They also show that low efficiency P- and N-type channels could trigger mild release and that high-efficiency facilitation channels may underlie the massive catecholamine release that occurs during the 'fight or flight' response.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / pharmacology
  • Calcium / metabolism
  • Calcium Channel Blockers / pharmacology
  • Calcium Channels / classification
  • Calcium Channels / drug effects
  • Calcium Channels / metabolism*
  • Catecholamines / metabolism
  • Chromaffin System / cytology
  • Chromaffin System / drug effects
  • Chromaffin System / metabolism*
  • Exocytosis
  • Nisoldipine / pharmacology
  • Peptides / pharmacology
  • Spider Venoms / pharmacology
  • omega-Agatoxin IVA
  • omega-Conotoxin GVIA


  • Calcium Channel Blockers
  • Calcium Channels
  • Catecholamines
  • Peptides
  • Spider Venoms
  • omega-Agatoxin IVA
  • Nisoldipine
  • 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine
  • omega-Conotoxin GVIA
  • Calcium