Channels underlying the slow afterhyperpolarization in hippocampal pyramidal neurons: neurotransmitters modulate the open probability

Neuron. 1995 Aug;15(2):435-41. doi: 10.1016/0896-6273(95)90047-0.


The slow afterhyperpolarization in hippocampal pyramidal neurons is mediated by a calcium-activated potassium current (IAHP) and is a target for variety of different neurotransmitters. The characteristics of the channels underlying IAHP and how they are modulated by neurotransmitters are, however, unknown. In this study, we have examined the properties of the channels underlying IAHP using fluctuation analysis of the macroscopic current. Our results indicate that this channel has a unitary conductance of 2-5 pS and a mean open time of about 2 ms. When the peak amplitude of IAHP was maximal, these channels have an open probability of 0.4. Noradrenaline and carbachol reduced IAHP amplitude by lowering open channel probability. These result indicate that a novel calcium-activated potassium channel underlies IAHP. This channel is modulated in a similar fashion by two different transmitter systems that utilize distinct protein kinases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 6-Cyano-7-nitroquinoxaline-2,3-dione / pharmacology
  • Calcium / pharmacology
  • Carbachol / pharmacology
  • Egtazic Acid / analogs & derivatives
  • Egtazic Acid / pharmacology
  • Ion Channel Gating / drug effects
  • Ion Channel Gating / physiology
  • Membrane Potentials / physiology
  • Nerve Tissue Proteins / metabolism
  • Neurotransmitter Agents / pharmacology
  • Neurotransmitter Agents / physiology*
  • Norepinephrine / pharmacology
  • Phosphorylation
  • Potassium / metabolism
  • Potassium Channels / drug effects
  • Potassium Channels / physiology*
  • Protein Kinases / metabolism
  • Protein Processing, Post-Translational
  • Pyramidal Cells / drug effects
  • Pyramidal Cells / physiology*
  • Signal Transduction / drug effects
  • Signal Transduction / physiology


  • Nerve Tissue Proteins
  • Neurotransmitter Agents
  • Potassium Channels
  • Egtazic Acid
  • 6-Cyano-7-nitroquinoxaline-2,3-dione
  • Carbachol
  • Protein Kinases
  • 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid
  • Potassium
  • Calcium
  • Norepinephrine