Glutamate receptor channels in rat DRG neurons: activation by kainate and quisqualate and blockade of desensitization by Con A.
Primary afferent C fibers in rat dorsal roots are depolarized by the excitatory amino acids kainate and domoate. Under whole-cell voltage clamp, kainate and domoate increase membrane conductance in a subpopulation of freshly dissociated DRG neurons. In contrast to kainate currents observed in CNS neurons, responses to kainate and domoate in DRG cells desensitize with prolonged agonist exposure. Half-maximal activation is achieved with much lower concentrations of kainate and domoate in sensory neurons than in CNS neurons from cerebral cortex. Rapid applications of glutamate, quisqualate, and AMPA evoke a transient current in DRG neurons and desensitize cells to subsequent applications of kainate or domoate. Brief incubation with the lectin concanavalin A eliminates desensitization to excitatory amino acids; after treatment with concanavalin A, all five agonists gate sustained currents of similar amplitude via the same receptor.
Huettner
J E
JE
Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115.
D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D003208:Concanavalin A / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism*; D007608:Kainic Acid / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009474:Neurons / Q000378:metabolism*; D010069:Oxadiazoles / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D016318:Quisqualic Acid; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter / Q000502:physiology*
D000596:Amino Acids; D010069:Oxadiazoles; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter; D003208:Concanavalin A; D016318:Quisqualic Acid; C012301:domoic acid; D007608:Kainic Acid