Differences in Ca2+ permeability of AMPA-type glutamate receptor channels in neocortical neurons caused by differential GluR-B subunit expression.
Fast excitatory synaptic transmission in the CNS is mediated by AMPA-type glutamate receptor (GluR) channels. Heterologous expression suggested that the Ca2+ permeability of these receptors critically depends on the subunit composition. Using patch-clamp techniques in brain slices, we found that the Ca2+ permeability of native AMPA-type GluRs was markedly higher in nonpyramidal (PCa/PK approximately 0.63) than in pyramidal (PCa/PK approximately 0.05) neurons of rat neocortex. Analysis of mRNA in single cells indicated that the relative abundance of GluR-B-specific mRNA was significantly lower in nonpyramidal (GluR-B/GluR-non-B approximately 0.3) than in pyramidal (GluR-B/GluR-non-B approximately 3) cells. This suggests that differences in relative abundance of GluR-B-specific mRNA generate functional diversity of AMPA-type GluRs in neurons with respect to Ca2+ permeability.
Max-Planck-Institut für medizinische Forschung Abteilung Zellphysiologie, Heidelberg, Federal Republic of Germany.
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P
Jonas
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C
Racca
B
B
Sakmann
P H
PH
Seeburg
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H
Monyer
D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology*; D002540:Cerebral Cortex / Q000502:physiology*; D017931:DNA Primers; D015870:Gene Expression; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D008564:Membrane Potentials / Q000502:physiology; D008969:Molecular Sequence Data; D009474:Neurons / Q000502:physiology*; D016133:Polymerase Chain Reaction; D017966:Pyramidal Cells / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000502:physiology*; D017470:Receptors, Glutamate / Q000096:biosynthesis*; D014793:Visual Cortex / Q000502:physiology*
D015220:Calcium Channels; D017931:DNA Primers; D046911:Macromolecular Substances; D012333:RNA, Messenger; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; D002118:Calcium