Activation and inactivation properties of voltage-gated calcium currents in developing cat retinal ganglion cells

S. J. Huang, David Robinson

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The correlated activity of developing retinal ganglion cells is essential for the reorganization and refinement of retinogeniculate projections. Previous studies have uncovered marked changes in the spiking properties of retinal ganglion cells during this period of reorganization; however, a full understanding of the changes in the underlying ionic conductances has yet to he obtained. To this end, the whole-cell configuration of the patch-clamp technique was used to record currents conducted by voltage-gated calcium channels in 83 dissociated cat retina] ganglion cells obtained from animals aged between embryonic day 34 and postnatal day 105. Calcium currents, magnified by using barium as the major charge carrier, were isolated by substituting choline for Na+ in the bathing solution and Cs+ for K+ in the electrode solution. Three voltage-gated Ca2+ conductances were identified based on their voltage dependence and kinetics of activation and inactivation: a transient low-voltage-activated conductance, a transient high-voltage-activated conductance and a sustained high-voltage-activated conductance. During the developmental period examined there were significant increases in the densities of all three conductances, as well as significant changes in some of their activation and inactivation properties. These findings, together with those reported previously for the voltage-gated Na+ and K+ conductances, are related to the generation of excitability in developing retinal ganglion cells during a period critical to the normal development of the visual system. Furthermore, while the sustained high-voltage-activated conductance was present in all of the retinal ganglion cells observed, only about 72% expressed the transient high-voltage-activated current. During the developmental period examined, there was also an increase in the proportion of cells expressing the transient low-voltage-activated conductance. This, along with our previous finding that retinal ganglion cells heterogeneously express different types of voltage-gated K+ channels, strongly suggests that the spiking patterns observed in different classes of retinal ganglion cell may be due, in part, to their intrinsic membrane properties.

Original languageEnglish (US)
Pages (from-to)239-247
Number of pages9
JournalNeuroscience
Volume85
Issue number1
DOIs
StatePublished - Mar 26 1998
Externally publishedYes

Fingerprint

Retinal Ganglion Cells
Cats
Calcium
Voltage-Gated Potassium Channels
Patch-Clamp Techniques
Barium
Calcium Channels
Choline
Ganglia
Retina
Electrodes
Membranes

Keywords

  • Activation properties
  • Development
  • Electrophysiology
  • Inactivation properties
  • Retinal ganglion cell
  • Voltage-gated calcium currents

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Activation and inactivation properties of voltage-gated calcium currents in developing cat retinal ganglion cells. / Huang, S. J.; Robinson, David.

In: Neuroscience, Vol. 85, No. 1, 26.03.1998, p. 239-247.

Research output: Contribution to journalArticle

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abstract = "The correlated activity of developing retinal ganglion cells is essential for the reorganization and refinement of retinogeniculate projections. Previous studies have uncovered marked changes in the spiking properties of retinal ganglion cells during this period of reorganization; however, a full understanding of the changes in the underlying ionic conductances has yet to he obtained. To this end, the whole-cell configuration of the patch-clamp technique was used to record currents conducted by voltage-gated calcium channels in 83 dissociated cat retina] ganglion cells obtained from animals aged between embryonic day 34 and postnatal day 105. Calcium currents, magnified by using barium as the major charge carrier, were isolated by substituting choline for Na+ in the bathing solution and Cs+ for K+ in the electrode solution. Three voltage-gated Ca2+ conductances were identified based on their voltage dependence and kinetics of activation and inactivation: a transient low-voltage-activated conductance, a transient high-voltage-activated conductance and a sustained high-voltage-activated conductance. During the developmental period examined there were significant increases in the densities of all three conductances, as well as significant changes in some of their activation and inactivation properties. These findings, together with those reported previously for the voltage-gated Na+ and K+ conductances, are related to the generation of excitability in developing retinal ganglion cells during a period critical to the normal development of the visual system. Furthermore, while the sustained high-voltage-activated conductance was present in all of the retinal ganglion cells observed, only about 72{\%} expressed the transient high-voltage-activated current. During the developmental period examined, there was also an increase in the proportion of cells expressing the transient low-voltage-activated conductance. This, along with our previous finding that retinal ganglion cells heterogeneously express different types of voltage-gated K+ channels, strongly suggests that the spiking patterns observed in different classes of retinal ganglion cell may be due, in part, to their intrinsic membrane properties.",
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