Calcium-induced calcium release in rod photoreceptor terminals boosts synaptic transmission during maintained depolarization

Lucia Cadetti, Eric J. Bryson, Cory A. Ciccone, Katalin Rabl, Wallace B Thoreson

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

We examined the contribution of calcium-induced calcium release (CICR) to synaptic transmission from rod photoreceptor terminals. Whole-cell recording and confocal calcium imaging experiments were conducted on rods with intact synaptic terminals in a retinal slice preparation from salamander. Low concentrations of ryanodine stimulated calcium increases in rod terminals, consistent with the presence of ryanodine receptors. Application of strong depolarizing steps (-70 to -10 mV) exceeding 200 ms or longer in duration evoked a wave of calcium that spread across the synaptic terminals of voltage-clamped rods. This secondary calcium increase was blocked by high concentrations of ryanodine, indicating it was due to CICR. Ryanodine (50 μm) had no significant effect on rod calcium current (Ica) although it slightly diminished rod light-evoked voltage responses. Bath application of 50 μm ryanodine strongly inhibited light-evoked currents in horizontal cells. Whether applied extracellularly or delivered into the rod cell through the patch pipette, ryanodine (50 μm) also inhibited excitatory post-synaptic currents (EPSCs) evoked in horizontal cells by depolarizing steps applied to rods. Ryanodine caused a preferential reduction in the later portions of EPSCs evoked by depolarizing steps of 200 ms or longer. These results indicate that CICR enhances calcium increases in rod terminals evoked by sustained depolarization, which in turn acts to boost synaptic exocytosis from rods.

Original languageEnglish (US)
Pages (from-to)2983-2990
Number of pages8
JournalEuropean Journal of Neuroscience
Volume23
Issue number11
DOIs
StatePublished - Jun 1 2006

Fingerprint

Retinal Rod Photoreceptor Cells
Synaptic Transmission
Ryanodine
Calcium
Presynaptic Terminals
Light
Urodela
Ryanodine Receptor Calcium Release Channel
Calcium Signaling
Exocytosis
Patch-Clamp Techniques
Baths

Keywords

  • Bipolar cell
  • Calcium stores
  • Horizontal cell
  • Retina
  • Ryanodine
  • Salamander

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Calcium-induced calcium release in rod photoreceptor terminals boosts synaptic transmission during maintained depolarization. / Cadetti, Lucia; Bryson, Eric J.; Ciccone, Cory A.; Rabl, Katalin; Thoreson, Wallace B.

In: European Journal of Neuroscience, Vol. 23, No. 11, 01.06.2006, p. 2983-2990.

Research output: Contribution to journalArticle

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