Spermine blocks synaptic transmission mediated by Ca(2+)-permeable AMPA receptors.
AMPA-gated glutamate receptors with outward rectification (type I receptors) are almost impermeable to Ca2+, while those with strong inward rectification (type II receptors) have high Ca2+ permeability. In the present study current responses in rat hippocampal neurones mediated by type II AMPA receptors were blocked by application of spermine to the external solution (IC50 = 170 microM), but those mediated by type I AMPA receptors were not affected. Furthermore, in putative non-pyramidal neurones in rat hippocampal slices, EPSCs mediated by type II AMPA receptors were markedly reduced by 1mM spermine, while those mediated by type I AMPA receptors were much less affected. Thus, external spermine exerts differential blocking action on the two different types of AMPA receptors.
Isa
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Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
Iino
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Ozawa
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S
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D007478:Iontophoresis; D007608:Kainic Acid / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D018408:Patch-Clamp Techniques; D051381:Rats; D018091:Receptors, AMPA / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D013096:Spermine / Q000494:pharmacology*; D009435:Synaptic Transmission / Q000187:drug effects*
D018690:Excitatory Amino Acid Agonists; D018091:Receptors, AMPA; D013096:Spermine; D007608:Kainic Acid; D002118:Calcium