Concentration-dependent substate behavior of native AMPA receptors.
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.
Smith
T C
TC
Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA.
Howe
J R
JR
D000818:Animals; D000831:Animals, Newborn; D004305:Dose-Response Relationship, Drug; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D018698:Glutamic Acid / Q000378:metabolism* / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D007608:Kainic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D009467:Neuromuscular Depolarizing Agents / Q000494:pharmacology; D009924:Organ Culture Techniques; D011810:Quinoxalines / Q000494:pharmacology; D018091:Receptors, AMPA / Q000819:agonists / Q000187:drug effects / Q000378:metabolism*; D018092:Kainic Acid Receptors / Q000819:agonists / Q000187:drug effects / Q000378:metabolism*; D013570:Synaptic Membranes / Q000187:drug effects / Q000378:metabolism*
D018691:Excitatory Amino Acid Antagonists; D018698:Glutamic Acid; D007473:Ion Channels; D007608:Kainic Acid; D009467:Neuromuscular Depolarizing Agents; D011810:Quinoxalines; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors; C062865:2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline; C012301:domoic acid