Abstract
AMPA-type glutamate receptors mediate most excitatory postsynaptic currents (EPSCs) at central synapses, and their conductance determines in part the size of EPSCs. The conductance of a recombinant AMPA receptor depends on the number of agonist molecules bound to the channel. Here we tested whether native AMPA and kainate receptors show this behavior in outside-out patches from neurons in situ by measuring conductance levels of single channels over a wide range of agonist concentrations. We found that the conductance of AMPA, but not kainate, receptors depended strongly on agonist concentration. Our results suggest that alterations in the glutamate concentration in the synaptic cleft may change the apparent unitary conductance of postsynaptic AMPA receptors.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Animals, Newborn
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Dose-Response Relationship, Drug
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Excitatory Amino Acid Antagonists / pharmacology
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Excitatory Postsynaptic Potentials / drug effects
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Excitatory Postsynaptic Potentials / physiology*
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Glutamic Acid / metabolism*
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Glutamic Acid / pharmacology
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Ion Channels / drug effects
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Ion Channels / metabolism*
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Kainic Acid / analogs & derivatives
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Kainic Acid / pharmacology
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Mice
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Mice, Inbred C57BL
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Neuromuscular Depolarizing Agents / pharmacology
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Organ Culture Techniques
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Quinoxalines / pharmacology
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Receptors, AMPA / agonists
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Receptors, AMPA / drug effects
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Receptors, AMPA / metabolism*
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Receptors, Kainic Acid / agonists
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Receptors, Kainic Acid / drug effects
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Receptors, Kainic Acid / metabolism*
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Synaptic Membranes / drug effects
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Synaptic Membranes / metabolism*
Substances
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Excitatory Amino Acid Antagonists
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Ion Channels
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Neuromuscular Depolarizing Agents
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Quinoxalines
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Receptors, AMPA
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Receptors, Kainic Acid
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2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline
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Glutamic Acid
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domoic acid
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Kainic Acid