Modulation of excitability by α-dendrotoxin-sensitive potassium channels in neocortical pyramidal neurons

dc.contributor.authorBekkers, John
dc.contributor.authorDelaney, Andrew James
dc.date.accessioned2015-12-10T22:44:03Z
dc.date.available2015-12-10T22:44:03Z
dc.date.issued2001
dc.date.updated2015-12-09T11:19:33Z
dc.description.abstractMany neurons transduce synaptic inputs into action potentials (APs) according to rules that reflect their intrinsic membrane properties. Voltage-gated potassium channels, being numerous and diverse constituents of neuronal membrane, are important participants in neuronal excitability and thus in synaptic integration. Here we address the role of dendrotoxin-sensitive "D-type" potassium channels in the excitability of large pyramidal neurons in layer 5 of the rat neocortex. Low concentrations of 4-aminopyridine or α-dendrotoxin (α-DTX) dramatically increased excitability: the firing threshold for action potentials was hyperpolarized by 4-8 mV, and the firing frequency during a 1-sec-long 500 pA somatic current step was doubled. In nucleated outside-out patches pulled from the soma, α-DTX reversibly blocked a slowly inactivating potassium current that comprised ∼6% of the total. This current first turned on at voltages just hyperpolarized to the threshold for spiking and activated steeply with depolarization. By assaying α-DTX-sensitive current in outside-out patches pulled from the axon and primary apical dendrite, it was found that this current was concentrated near the soma. We conclude that α-DTX-sensitive channels are present on large layer 5 pyramidal neurons at relatively low density, but their strategic location close to the site of action potential initiation in the axon may ensure that they have a disproportionate effect on neuronal excitability. Modulation of this class of channel would generate a powerful upregulation or downregulation of neuronal output after the integration of synaptic inputs.
dc.identifier.issn0270-6474
dc.identifier.urihttp://hdl.handle.net/1885/58429
dc.publisherSociety for Neuroscience
dc.sourceJournal of Neuroscience
dc.subjectKeywords: 4 aminopyridine; dendrotoxin; potassium channel; action potential; animal cell; article; cell density; controlled study; dendrite; hyperpolarization; membrane depolarization; neocortex; nerve cell excitability; nerve fiber; newborn; nonhuman; potassium cu Action potential; D-current; Dendrite; Dendrotoxin; Neocortex; Potassium channel; Pyramidal neuron
dc.titleModulation of excitability by α-dendrotoxin-sensitive potassium channels in neocortical pyramidal neurons
dc.typeJournal article
local.bibliographicCitation.issue17
local.bibliographicCitation.lastpage6560
local.bibliographicCitation.startpage6553
local.contributor.affiliationBekkers, John, College of Medicine, Biology and Environment, ANU
local.contributor.affiliationDelaney, Andrew James, College of Medicine, Biology and Environment, ANU
local.contributor.authoremailu9109873@anu.edu.au
local.contributor.authoruidBekkers, John, u9109873
local.contributor.authoruidDelaney, Andrew James, u980680
local.description.notesImported from ARIES
local.description.refereedYes
local.identifier.absfor110902 - Cellular Nervous System
local.identifier.ariespublicationMigratedxPub442
local.identifier.citationvolume21
local.identifier.scopusID2-s2.0-0035449999
local.identifier.uidSubmittedByMigrated
local.type.statusPublished Version

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