Ca(2+)-activated K+ currents underlying the afterhyperpolarization in guinea pig vagal neurons: a role for Ca(2+)-activated Ca2+ release

Neuron. 1991 Aug;7(2):257-64. doi: 10.1016/0896-6273(91)90264-z.


We examined the possibility that Ca2+ released from intracellular stores could activate K+ currents underlying the afterhyperpolarization (AHP) in neurons. In neurons of the dorsal motor nucleus of the vagus, the current underlying the AHP had two components: a rapidly decaying component that was maximal following the action potential (GkCa,1) and a slower component that had a distinct rising phase (GkCa,2). Both components required influx of extracellular Ca2+ for their activation, and neither was blocked by extracellular TEA (10 mM). GkCa,1 was selectively blocked by apamin, whereas GkCa,2 was selectively reduced by noradrenaline. The time course of GkCa,2 was markedly temperature sensitive. GkCa,2 was selectively blocked by application of ryanodine or sodium dantrolene, or by loading cells with ruthenium red. These results suggest that influx of Ca2+ directly gates one class of K+ channels and leads to release of Ca2+ from intracellular stores, which activates a different class of K+ channel.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology*
  • Animals
  • Apamin / pharmacology
  • Biological Transport / drug effects
  • Calcium / metabolism
  • Calcium / physiology*
  • Dantrolene / pharmacology
  • Electric Conductivity / drug effects
  • Electric Conductivity / physiology
  • Guinea Pigs
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Norepinephrine / pharmacology
  • Potassium / pharmacokinetics*
  • Potassium Channels / drug effects
  • Potassium Channels / physiology
  • Ryanodine / pharmacology
  • Tetraethylammonium
  • Tetraethylammonium Compounds / pharmacology
  • Vagus Nerve / metabolism
  • Vagus Nerve / physiology*


  • Potassium Channels
  • Tetraethylammonium Compounds
  • Ryanodine
  • Apamin
  • Tetraethylammonium
  • Dantrolene
  • Potassium
  • Calcium
  • Norepinephrine