GABA transporters regulate a standing GABAC receptor-mediated current at a retinal presynaptic terminal

Court Hull, Geng Lin Li, Henrique Von Gersdorff

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


At the axon terminal of goldfish retinal bipolar cells, GABAC receptors have been shown to mediate inhibitory reciprocal synaptic currents. Here, we demonstrate a novel standing GABAergic current mediated exclusively by GABAC receptors. Selective inhibition of GAT-1 GABA transporters on amacrine cells increases this tonic current and reveals a specific functional coupling between GAT-1 transporters and GABAC receptors. We propose that this GABAC receptor-mediated standing current serves to regulate synaptic gain by shunting depolarizing potentials that can produce Ca 2+-dependent action potentials at the bipolar cell terminal. Furthermore, we find that the amount of GABAC receptor-mediated reciprocal feedback between bipolar cell terminals and amacrine cells is greatly increased when GAT-1 transporters are specifically blocked by NO-711 (1-[2-[[(diphenylmethylene)imino]oxy]ethyl]-1,2,5,6-tetrahydro-3- pyridinecarboxylic acid hydrochloride). The involvement of GAT-1 transporters in regulating this standing (or tonic) GABAC current implicates them in a novel role as major determinants of presynaptic excitability.

Original languageEnglish (US)
Pages (from-to)6979-6984
Number of pages6
JournalJournal of Neuroscience
Issue number26
StatePublished - 2006


  • Bipolar cell
  • GAT-1
  • Gaba transporters
  • Presynaptic excitability
  • Retina
  • Tonic inhibition

ASJC Scopus subject areas

  • Neuroscience(all)


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