Calcium ion levels in resting and depolarized goldfish retinal ganglion cell somata and growth cones

Andrew Ishida, V. P. Bindokas, R. Nuccitelli

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

We have estimated free, intracellular calcium ion concentrations ([Ca](i)) in isolated retinal ganglion cells of adult goldfish by ratio-imaging fura-2 emission intensity at two excitation wavelengths. Here we describe [Ca](i) in these cells, both at rest and during depolarization by elevated levels of extracellular potassium ions ([K](o)). [K](o) was varied between 5 and 60 mM in sodium-free, tetrodotoxin-containing salines. Ganglion cell membrane potential, measured with patch electrodes, fell with each increment of [K](o) used, from ~-70 mV in 5 mM K+ to ~-20 mV in 60 mM K+. In control saline, [Ca](i) was roughly 120 nM in cell somata and at least twofold higher in their growth cones. [Ca](i) increased in both somata and growth cones to as high as 1.5 μM in salines containing 60 mM K+. [Ca](i) exceeded 1.5 μM in some cells in high-K+ salines, although these levels could not be quantified accurately with fura-2. Increases in [Ca](i) elicited by elevated [K](o) persisted for the duration of the exposure to high-K+ saline and were blocked by replacement of most of the bath Ca2+ by Co2+. These increases in [Ca](i) were also sensitive to dihydropyridine calcium-channel ligands, viz., enhanced by BAY K 8644 (3 μM) and antagonized by nifedipine (10 μM). Partial recovery of control [Ca](i) occurred when [K](o) was reduced to 5 mM after exposure to high-K+ saline and in high-K+ saline when nifedipine was included. These results show that goldfish retinal ganglion cells can partially buffer intracellular Ca2+ in the absence of extracellular Na+ ions. These results provide measurements of the changes in [Ca](i) brought about by depolarization of goldfish retinal ganglion cells in Na+-free salines. In these salines, at least part of the increase in [Ca](i) appears to result from Ca2+ influx through a voltage-activated, noninactivating calcium conductance in the somata and growth cones of these cells. These measurements complement whole-cell patch-clamp and vibrating microprobe recordings from the somata and neurites of these cells and also immunocytochemical studies and patch-clamp measurements in amphibian, reptilian, and mammalian retinal ganglion cells.

Original languageEnglish (US)
Pages (from-to)968-979
Number of pages12
JournalJournal of Neurophysiology
Volume65
Issue number4
StatePublished - 1991

Fingerprint

Growth Cones
Goldfish
Retinal Ganglion Cells
Carisoprodol
Ions
Calcium
Fura-2
Nifedipine
Tetrodotoxin
Amphibians
Neurites
Calcium Channels
Baths
Ganglia
Membrane Potentials
Potassium
Buffers
Electrodes
Sodium
Cell Membrane

ASJC Scopus subject areas

  • Physiology
  • Neuroscience(all)

Cite this

Calcium ion levels in resting and depolarized goldfish retinal ganglion cell somata and growth cones. / Ishida, Andrew; Bindokas, V. P.; Nuccitelli, R.

In: Journal of Neurophysiology, Vol. 65, No. 4, 1991, p. 968-979.

Research output: Contribution to journalArticle

Ishida, Andrew ; Bindokas, V. P. ; Nuccitelli, R. / Calcium ion levels in resting and depolarized goldfish retinal ganglion cell somata and growth cones. In: Journal of Neurophysiology. 1991 ; Vol. 65, No. 4. pp. 968-979.
@article{49b4da374da24a0182c89daa2e48e7c0,
title = "Calcium ion levels in resting and depolarized goldfish retinal ganglion cell somata and growth cones",
abstract = "We have estimated free, intracellular calcium ion concentrations ([Ca](i)) in isolated retinal ganglion cells of adult goldfish by ratio-imaging fura-2 emission intensity at two excitation wavelengths. Here we describe [Ca](i) in these cells, both at rest and during depolarization by elevated levels of extracellular potassium ions ([K](o)). [K](o) was varied between 5 and 60 mM in sodium-free, tetrodotoxin-containing salines. Ganglion cell membrane potential, measured with patch electrodes, fell with each increment of [K](o) used, from ~-70 mV in 5 mM K+ to ~-20 mV in 60 mM K+. In control saline, [Ca](i) was roughly 120 nM in cell somata and at least twofold higher in their growth cones. [Ca](i) increased in both somata and growth cones to as high as 1.5 μM in salines containing 60 mM K+. [Ca](i) exceeded 1.5 μM in some cells in high-K+ salines, although these levels could not be quantified accurately with fura-2. Increases in [Ca](i) elicited by elevated [K](o) persisted for the duration of the exposure to high-K+ saline and were blocked by replacement of most of the bath Ca2+ by Co2+. These increases in [Ca](i) were also sensitive to dihydropyridine calcium-channel ligands, viz., enhanced by BAY K 8644 (3 μM) and antagonized by nifedipine (10 μM). Partial recovery of control [Ca](i) occurred when [K](o) was reduced to 5 mM after exposure to high-K+ saline and in high-K+ saline when nifedipine was included. These results show that goldfish retinal ganglion cells can partially buffer intracellular Ca2+ in the absence of extracellular Na+ ions. These results provide measurements of the changes in [Ca](i) brought about by depolarization of goldfish retinal ganglion cells in Na+-free salines. In these salines, at least part of the increase in [Ca](i) appears to result from Ca2+ influx through a voltage-activated, noninactivating calcium conductance in the somata and growth cones of these cells. These measurements complement whole-cell patch-clamp and vibrating microprobe recordings from the somata and neurites of these cells and also immunocytochemical studies and patch-clamp measurements in amphibian, reptilian, and mammalian retinal ganglion cells.",
author = "Andrew Ishida and Bindokas, {V. P.} and R. Nuccitelli",
year = "1991",
language = "English (US)",
volume = "65",
pages = "968--979",
journal = "Journal of Neurophysiology",
issn = "0022-3077",
publisher = "American Physiological Society",
number = "4",

}

TY - JOUR

T1 - Calcium ion levels in resting and depolarized goldfish retinal ganglion cell somata and growth cones

AU - Ishida, Andrew

AU - Bindokas, V. P.

AU - Nuccitelli, R.

PY - 1991

Y1 - 1991

N2 - We have estimated free, intracellular calcium ion concentrations ([Ca](i)) in isolated retinal ganglion cells of adult goldfish by ratio-imaging fura-2 emission intensity at two excitation wavelengths. Here we describe [Ca](i) in these cells, both at rest and during depolarization by elevated levels of extracellular potassium ions ([K](o)). [K](o) was varied between 5 and 60 mM in sodium-free, tetrodotoxin-containing salines. Ganglion cell membrane potential, measured with patch electrodes, fell with each increment of [K](o) used, from ~-70 mV in 5 mM K+ to ~-20 mV in 60 mM K+. In control saline, [Ca](i) was roughly 120 nM in cell somata and at least twofold higher in their growth cones. [Ca](i) increased in both somata and growth cones to as high as 1.5 μM in salines containing 60 mM K+. [Ca](i) exceeded 1.5 μM in some cells in high-K+ salines, although these levels could not be quantified accurately with fura-2. Increases in [Ca](i) elicited by elevated [K](o) persisted for the duration of the exposure to high-K+ saline and were blocked by replacement of most of the bath Ca2+ by Co2+. These increases in [Ca](i) were also sensitive to dihydropyridine calcium-channel ligands, viz., enhanced by BAY K 8644 (3 μM) and antagonized by nifedipine (10 μM). Partial recovery of control [Ca](i) occurred when [K](o) was reduced to 5 mM after exposure to high-K+ saline and in high-K+ saline when nifedipine was included. These results show that goldfish retinal ganglion cells can partially buffer intracellular Ca2+ in the absence of extracellular Na+ ions. These results provide measurements of the changes in [Ca](i) brought about by depolarization of goldfish retinal ganglion cells in Na+-free salines. In these salines, at least part of the increase in [Ca](i) appears to result from Ca2+ influx through a voltage-activated, noninactivating calcium conductance in the somata and growth cones of these cells. These measurements complement whole-cell patch-clamp and vibrating microprobe recordings from the somata and neurites of these cells and also immunocytochemical studies and patch-clamp measurements in amphibian, reptilian, and mammalian retinal ganglion cells.

AB - We have estimated free, intracellular calcium ion concentrations ([Ca](i)) in isolated retinal ganglion cells of adult goldfish by ratio-imaging fura-2 emission intensity at two excitation wavelengths. Here we describe [Ca](i) in these cells, both at rest and during depolarization by elevated levels of extracellular potassium ions ([K](o)). [K](o) was varied between 5 and 60 mM in sodium-free, tetrodotoxin-containing salines. Ganglion cell membrane potential, measured with patch electrodes, fell with each increment of [K](o) used, from ~-70 mV in 5 mM K+ to ~-20 mV in 60 mM K+. In control saline, [Ca](i) was roughly 120 nM in cell somata and at least twofold higher in their growth cones. [Ca](i) increased in both somata and growth cones to as high as 1.5 μM in salines containing 60 mM K+. [Ca](i) exceeded 1.5 μM in some cells in high-K+ salines, although these levels could not be quantified accurately with fura-2. Increases in [Ca](i) elicited by elevated [K](o) persisted for the duration of the exposure to high-K+ saline and were blocked by replacement of most of the bath Ca2+ by Co2+. These increases in [Ca](i) were also sensitive to dihydropyridine calcium-channel ligands, viz., enhanced by BAY K 8644 (3 μM) and antagonized by nifedipine (10 μM). Partial recovery of control [Ca](i) occurred when [K](o) was reduced to 5 mM after exposure to high-K+ saline and in high-K+ saline when nifedipine was included. These results show that goldfish retinal ganglion cells can partially buffer intracellular Ca2+ in the absence of extracellular Na+ ions. These results provide measurements of the changes in [Ca](i) brought about by depolarization of goldfish retinal ganglion cells in Na+-free salines. In these salines, at least part of the increase in [Ca](i) appears to result from Ca2+ influx through a voltage-activated, noninactivating calcium conductance in the somata and growth cones of these cells. These measurements complement whole-cell patch-clamp and vibrating microprobe recordings from the somata and neurites of these cells and also immunocytochemical studies and patch-clamp measurements in amphibian, reptilian, and mammalian retinal ganglion cells.

UR - http://www.scopus.com/inward/record.url?scp=0025869526&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0025869526&partnerID=8YFLogxK

M3 - Article

C2 - 1711108

AN - SCOPUS:0025869526

VL - 65

SP - 968

EP - 979

JO - Journal of Neurophysiology

JF - Journal of Neurophysiology

SN - 0022-3077

IS - 4

ER -