Further evidence for calcium permeability of non-NMDA receptor channels in hippocampal neurons

Neurosci Res. 1992 Jan;12(5):606-16. doi: 10.1016/0168-0102(92)90067-m.

Abstract

We have previously suggested that kainic acid (KA) increases the fluorescence of a fluoroprobe for Ca2+ via activation of the non-NMDA (N-methyl-D-aspartic acid) receptor in cultured hippocampal cells. The present study provides further evidence to support this suggestion. KA and NMDA increased the fluorescence occasionally in different subcellular loci of a single cell for each agonist, excluding the possibility that KA activated the NMDA receptor. KA elevated fluorescence in the cell whose membrane was voltage-clamped, thus eliminating possible Ca2+ entry through voltage-dependent channels. A monophasic response to KA was found to occur in the cells identified immunochemically as neurons. Even when the cells were cultured at different embryonic stages, KA responsiveness reached a peak at a rather fixed timepoint through the total age of neurons, while NMDA responsiveness continued to increase. This suggests that the Ca(2+)-permeable non-NMDA receptor is expressed according to a genetic schedule, but not to an artifactual effect of cell culture.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Calcium Channels / metabolism*
  • Cells, Cultured
  • Gestational Age
  • Hippocampus / cytology*
  • Hippocampus / embryology
  • Ion Channel Gating / drug effects
  • N-Methylaspartate / pharmacology
  • Neurons / drug effects
  • Neurons / metabolism*
  • Permeability
  • Rats
  • Receptors, Kainic Acid
  • Receptors, N-Methyl-D-Aspartate / metabolism
  • Receptors, Neurotransmitter / drug effects*
  • Tetrodotoxin / pharmacology

Substances

  • Calcium Channels
  • Receptors, Kainic Acid
  • Receptors, N-Methyl-D-Aspartate
  • Receptors, Neurotransmitter
  • Tetrodotoxin
  • N-Methylaspartate
  • Calcium