Synaptically activated increases in Ca2+ concentration in hippocampal CA1 pyramidal cells are primarily due to voltage-gated Ca2+ channels

Neuron. 1992 Dec;9(6):1163-73. doi: 10.1016/0896-6273(92)90074-n.


Changes in intracellular Ca2+ concentration ([Ca2+]i) in the soma and dendrites of hippocampal CA1 pyramidal neurons were measured using intracellularly injected fura-2. A large component of the [Ca2+]i elevation caused by high frequency stimulation of the Schaffer collaterals was correlated with the Na+ spikes triggered by the excitatory postsynaptic potentials (EPSPs). These spikes were generated in the soma and proximal dendrites and stimulated Ca2+ entry through voltage-gated Ca2+ channels. Suppressing spikes by hyperpolarizing the soma or by injecting QX-314 revealed a smaller nonspike component of Ca2+ entry. A substantial fraction of this component was mediated by the action of the EPSPs on voltage-gated Ca2+ channels, because it persisted in 2-amino-5-phosphonovaleric acid and because it was usually reduced when Ca2+ channel activity was suppressed by hyperpolarization. Ca2+ entry through the N-methyl-D-aspartate receptor channel could not be detected with certainty, perhaps because it was highly localized.

Publication types

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

MeSH terms

  • 2-Amino-5-phosphonovalerate / pharmacology
  • Anesthetics, Local / pharmacology
  • Animals
  • Calcium / metabolism*
  • Calcium Channels / physiology*
  • Dendrites / physiology
  • Electric Stimulation
  • Evoked Potentials
  • Fura-2
  • Hippocampus / physiology*
  • In Vitro Techniques
  • Ion Channel Gating
  • Kinetics
  • Lidocaine / analogs & derivatives
  • Lidocaine / pharmacology
  • Male
  • Neurons / drug effects
  • Neurons / physiology*
  • Pyramidal Tracts / physiology*
  • Rats
  • Rats, Sprague-Dawley
  • Spectrometry, Fluorescence
  • Synapses / drug effects
  • Synapses / physiology*


  • Anesthetics, Local
  • Calcium Channels
  • QX-314
  • 2-Amino-5-phosphonovalerate
  • Lidocaine
  • Calcium
  • Fura-2