GABA(C) receptors on ferret retinal bipolar cells: A diversity of subtypes in mammals?

Peter D. Lukasiewicz, Rachel O.L. Wong

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34 Scopus citations


The GABA(C) receptor subtypes on bipolar cells of rats and cold-blooded vertebrates differ in their pharmacological properties and probably have different molecular compositions. With the exception of the rat, native GABA(C) receptors in mammals had not been studied. In ferret, whole-cell, voltage-clamp recordings were made from bipolar cells in the retinal slice preparation to determine which subtype of GABA(C) receptor predominated. Puff-evoked GABA currents in bipolar cells were partially reduced by the GABA(A) receptor antagonist bicuculline, indicating that both GABA(A) and GABA(C) receptors mediated the responses. By contrast, GABA currents of ganglion cells were always completely blocked by bicuculline, indicating that GABA(A) receptors predominated on these cells. Small-amplitude GABA currents of bipolar cells evoked by short-duration puffs were less sensitive to bicuculline than large-amplitude currents evoked by long-duration puffs. This indicates that GABA(C) receptors mediated proportionately more of the small-amplitude, puff-evoked responses and GABA(A) receptors mediated more of the large-amplitude, puff-evoked responses. In bipolar cells, the bicuculline-resistant component of the GABA current was entirely blocked by 3-APMPA (3-aminopropyl-(methyl)phosphonic acid), a GABA(C) receptor antagonist. Picrotoxin, which is relatively ineffective at rat GABA(C) receptors, completely blocked GABA currents in ferret bipolar cells, indicating that GABA(C) receptors on ferret bipolar cells resemble those in lower vertebrates rather than those in the rat retina. These results suggest that there may be a diversity of GABA(C) receptor subtypes on mammalian bipolar cells.

Original languageEnglish
Pages (from-to)989-994
Number of pages6
JournalVisual Neuroscience
Issue number5
StatePublished - 1997


  • Bipolar cell
  • Ferret
  • GABA(C) receptor
  • Picrotoxin
  • Retinal slice


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