Enhanced transmission of glutamate current flowing from the dendrite to the soma in rat neocortical layer 5 neurons.
The presence of tetrodotoxin (TTX)-sensitive slowly-inactivating Na+ channels in the dendrites of neocortical layer 5 neurons was tested by focal iontophoresis of glutamate on the dendrite while voltage clamping the soma and proximal dendrite. The glutamate-transmitted current was measured with the voltage clamp circuit. When the soma was depolarized the transmitted current increased indicating voltage-dependent properties in the dendrite. Over 50% of this increased voltage-dependence was blocked by TTX indicating a large portion of the enhanced dendro-somatic current was caused non-inactivating Na+ channel inward rectification. The glutamate-transmitted current measured with a voltage clamp of the soma at firing level was equal to the effective glutamate measured during repetitive firing.
Crill
Wayne E
WE
Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195-7280, USA.
Schwindt
Peter C
PC
Oakley
John C
JC
D000818:Animals; D003712:Dendrites / Q000187:drug effects / Q000502:physiology*; D018698:Glutamic Acid / Q000494:pharmacology / Q000502:physiology*; D019579:Neocortex / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
D015222:Sodium Channels; D018698:Glutamic Acid; D013779:Tetrodotoxin