Zn2+ modulates light responses of color-opponent bipolar and amacrine cells in the carp retina

Dong Gen Luo, Geng Lin Li, Xiong Li Yang

Research output: Contribution to journalArticle

Abstract

The effects of Zn2+ on color-opponent bipolar cells (BCs) and amacrine cells (ACs) were studied in the isolated superfused carp retina using intracellular recording techniques. Bath-applied Zn2+ (25μM) depolarized R+G--type BCs and suppressed both depolarizing responses of these cells to red (680nm) flashes and hyperpolarizing ones to green (500nm) flashes. Following Zn2+ application, G+R--type BCs were hyperpolarized, which was accompanied by a potentiation of their depolarizing responses to green flashes and a suppression of hyperpolarizing ones to red flashes. Similar Zn2+ effects were observed in R+G-- and G+R--type ACs. The Zn2+ effects persisted in the presence of picrotoxin and strychnine, suggesting that modulation by Zn2+ of GABA and glycine receptors was unlikely involved. Using whole-cell recording techniques, it was found Ca2+ currents in cone terminals were dose-dependently suppressed by Zn2+, suggesting that Zn2+ may reduce glutamate release from cone photoreceptors. Furthermore, lowering extracellular Ca2+, a procedure that increases glutamate release from photoreceptors, exerted actions on R+G-- and G+R--type BCs, almost opposite to the Zn2+ effects on these two types of BCs. It is therefore postulated that the Zn2+ effects reported in the present work may reflect a consequence of the changes in input resistances of color-opponent BCs and driving forces for their light responses resulted from the reduced glutamate release by Zn2+.

Original languageEnglish (US)
Pages (from-to)461-468
Number of pages8
JournalBrain Research Bulletin
Volume58
Issue number5
DOIs
StatePublished - Sep 15 2002

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Keywords

  • Amacrine cell
  • Bipolar cell
  • Carp retina
  • Color opponency
  • Zinc

ASJC Scopus subject areas

  • Neuroscience(all)

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