Abstract
Fast excitatory synaptic transmission in the CNS is mediated by AMPA-type glutamate receptor (GIuR) channels. Heterologous expression suggested that the Ca 2+ permeability of these receptors critically depends on the sub-unit composition. Using patch-clamp techniques in brain slices, we found that the Ca 2+ permeability of native AMPA-type GluRs was markedly higher in nonpyramidal ( P Ca P K ≈ 0.63 ) than in pyramidal ( P CaG P K ≈ 0.05 ) neurons of rat neocortex. Analysis of mRNA in single cells indicated that the relative abundance of GIuR-B-specific mRNA was significantly lower in nonpyramidal ( GluR-B GluR-non-B ≈ 0.3 ) than in pyramidal ( sol GluR-B GluRnon-B ≈ 3 ) cells. This suggests that differences in relative abundance of GIuR-B-specific mRNA generate functional diversity of AMPA-type GIuRs in neurons with respect to Ca 2+ permeability.
Published Version
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