title: Kainic acid blocks a TTX-sensitive sodium channel in retinal horizontal cells of the turtle (Pseudemys scripta elegans).
abstract: The aim of this study was to investigate the effects of excitatory amino acids on channels found in horizontal cell membranes using patch-clamp techniques. We unexpectedly found that the excitatory amino acid receptor agonist, kainic acid, reversibly inhibited the transient tetrodotoxin (TTX)-sensitive Na+ current in isolated horizontal cell bodies and axons from the retina of the turtle (Pseudemys scripta elegans). The effect of kainic acid was antagonized by the glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione. Kainic acid activated a non-selective cation current, a finding that was consistent with previous reports, and which would account for the kainate induced depolarisation of these cells. The inhibition of the transient TTX-sensitive Na+ current by kainic acid might be important in the modification of the kinetics of responses to excitatory amino acid analogues often observed during intracellular recording from these cells.
authors.affiliation: Department of Clinical Pharmacology, St. Vincent's Hospital, Darlinghurst, NSW, Australia.
authors.forename: D K
authors.initials: DK
authors.lastname: Martin
authors.forename: P J
authors.initials: PJ
authors.lastname: Anderton
authors.forename: J A
authors.initials: JA
authors.lastname: Bursill
authors.forename: A C
authors.initials: AC
authors.lastname: Le Dain
authors.forename: T J
authors.initials: TJ
authors.lastname: Millar
mesh_terms: D000818:Animals; D007608:Kainic Acid / Q000494:pharmacology*; D012160:Retina / Q000187:drug effects*; D015222:Sodium Channels / Q000187:drug effects*; D013779:Tetrodotoxin / Q000494:pharmacology*; D014426:Turtles
chemical_list: D015222:Sodium Channels; D013779:Tetrodotoxin; D007608:Kainic Acid