Tracking presynaptic Ca2+ dynamics during neurotransmitter release with Ca2+-activated K+ channels

Nat Neurosci. 2000 Jun;3(6):566-71. doi: 10.1038/75737.


Neurotransmitter release during action potentials is thought to require transient, localized [Ca2+]i as high as hundreds of micromolar near presynaptic release sites. Most experimental attempts to characterize the magnitude and time course of these Ca2+ domains involve optical methods that sample large volumes, require washout of endogenous buffers and often affect Ca2+ kinetics and transmitter release. Endogenous calcium-activated potassium (KCa) channels colocalize with presynaptic Ca2+ channels in Xenopus nerve-muscle cultures. We used these channels to quantify the rapid, dynamic changes in [Ca2+]i at active zones during synaptic activity. Confirming Ca2+-domain predictions, these KCa channels revealed [Ca2+]i over 100 microM during synaptic activity and much faster buildup and decay of Ca2+ domains than shown using other techniques.

Publication types

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

MeSH terms

  • Action Potentials / physiology
  • Animals
  • Calcium / metabolism*
  • Calcium Channel Blockers / pharmacology
  • Calcium Channels / metabolism
  • Cells, Cultured
  • Coculture Techniques
  • Excitatory Postsynaptic Potentials / physiology
  • Large-Conductance Calcium-Activated Potassium Channels
  • Muscles / cytology
  • Neurons / cytology
  • Neurons / metabolism*
  • Neurotransmitter Agents / metabolism*
  • Patch-Clamp Techniques
  • Peptides / pharmacology
  • Potassium Channel Blockers
  • Potassium Channels / metabolism*
  • Potassium Channels, Calcium-Activated*
  • Presynaptic Terminals / metabolism*
  • Reaction Time / physiology
  • Xenopus
  • omega-Conotoxin GVIA / pharmacology


  • Calcium Channel Blockers
  • Calcium Channels
  • Large-Conductance Calcium-Activated Potassium Channels
  • Neurotransmitter Agents
  • Peptides
  • Potassium Channel Blockers
  • Potassium Channels
  • Potassium Channels, Calcium-Activated
  • iberiotoxin
  • omega-Conotoxin GVIA
  • Calcium