Properties of K+ conductances in cat retinal ganglion cells during the period of activity-mediated refinements in retinofugal pathways

I. Skaliora, David Robinson, R. P. Scobey, L. M. Chalupa

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

During ontogeny retinal ganglion cells manifest pronounced changes in excitable membrane properties. To further our understanding of the ionic conductances underlying such functional changes, the whole-cell voltage-clamp variation of the patch-clamp technique was used to record potassium currents in 220 ganglion cells isolated by blocking voltage-gated Na+ and Ca2+ currents with tetrodoxin (TTX) and CoCl2 respectively and were characterized by their pharmacology, kinetics and voltage dependence of activation and inactivation. In all cases, a combination of three currents accounted for the total outward calcium-independent K+ current: (i) a steady linear conductance; (ii) a voltage-gated transient current, I(A), and (iii) a voltage-gated sustained current, I(K). Both voltage-gated currents were affected by the application of 4-aminopyridine and tetraethylammonia (TEA): I(A) showed a greater sensitivity to 4-aminopyridine, while I(K) was more sensitive to TEA. Both voltage-gated currents were present throughout the developmental period examined; however, the percentage of retinal ganglion cells (RGCs) expressing I(A) showed a marked decline from 82% at E31 to 45% at postnatal ages. During this development period there was an increase in the density of the two voltage-gated and the linear conductance. Additionally, with maturation, significantly slower inactivation kinetics were observed for I(K). These findings, and our previous results dealing with maturational changes in the TTX-sensitive voltage-gated Na current, are related to the generation of excitability in developing retinal ganglion cells. Furthermore, the presence of cells with and without transient K+ conductance throughout development suggests that the different spiking patterns observed in RGC classes may be partially due to differences in their membrane properties.

Original languageEnglish (US)
Pages (from-to)1558-1568
Number of pages11
JournalEuropean Journal of Neuroscience
Volume7
Issue number7
DOIs
StatePublished - 1995
Externally publishedYes

Fingerprint

Retinal Ganglion Cells
Cats
4-Aminopyridine
Membranes
Patch-Clamp Techniques
Ganglia
Potassium
Pharmacology
Calcium

Keywords

  • Development
  • Ion channels
  • Linear conductance
  • Patch-clamp recordings
  • Potassium currents

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Properties of K+ conductances in cat retinal ganglion cells during the period of activity-mediated refinements in retinofugal pathways. / Skaliora, I.; Robinson, David; Scobey, R. P.; Chalupa, L. M.

In: European Journal of Neuroscience, Vol. 7, No. 7, 1995, p. 1558-1568.

Research output: Contribution to journalArticle

@article{512dbfc1a28640eaa5aca24d517406f8,
title = "Properties of K+ conductances in cat retinal ganglion cells during the period of activity-mediated refinements in retinofugal pathways",
abstract = "During ontogeny retinal ganglion cells manifest pronounced changes in excitable membrane properties. To further our understanding of the ionic conductances underlying such functional changes, the whole-cell voltage-clamp variation of the patch-clamp technique was used to record potassium currents in 220 ganglion cells isolated by blocking voltage-gated Na+ and Ca2+ currents with tetrodoxin (TTX) and CoCl2 respectively and were characterized by their pharmacology, kinetics and voltage dependence of activation and inactivation. In all cases, a combination of three currents accounted for the total outward calcium-independent K+ current: (i) a steady linear conductance; (ii) a voltage-gated transient current, I(A), and (iii) a voltage-gated sustained current, I(K). Both voltage-gated currents were affected by the application of 4-aminopyridine and tetraethylammonia (TEA): I(A) showed a greater sensitivity to 4-aminopyridine, while I(K) was more sensitive to TEA. Both voltage-gated currents were present throughout the developmental period examined; however, the percentage of retinal ganglion cells (RGCs) expressing I(A) showed a marked decline from 82{\%} at E31 to 45{\%} at postnatal ages. During this development period there was an increase in the density of the two voltage-gated and the linear conductance. Additionally, with maturation, significantly slower inactivation kinetics were observed for I(K). These findings, and our previous results dealing with maturational changes in the TTX-sensitive voltage-gated Na current, are related to the generation of excitability in developing retinal ganglion cells. Furthermore, the presence of cells with and without transient K+ conductance throughout development suggests that the different spiking patterns observed in RGC classes may be partially due to differences in their membrane properties.",
keywords = "Development, Ion channels, Linear conductance, Patch-clamp recordings, Potassium currents",
author = "I. Skaliora and David Robinson and Scobey, {R. P.} and Chalupa, {L. M.}",
year = "1995",
doi = "10.1111/j.1460-9568.1995.tb01151.x",
language = "English (US)",
volume = "7",
pages = "1558--1568",
journal = "European Journal of Neuroscience",
issn = "0953-816X",
publisher = "Wiley-Blackwell",
number = "7",

}

TY - JOUR

T1 - Properties of K+ conductances in cat retinal ganglion cells during the period of activity-mediated refinements in retinofugal pathways

AU - Skaliora, I.

AU - Robinson, David

AU - Scobey, R. P.

AU - Chalupa, L. M.

PY - 1995

Y1 - 1995

N2 - During ontogeny retinal ganglion cells manifest pronounced changes in excitable membrane properties. To further our understanding of the ionic conductances underlying such functional changes, the whole-cell voltage-clamp variation of the patch-clamp technique was used to record potassium currents in 220 ganglion cells isolated by blocking voltage-gated Na+ and Ca2+ currents with tetrodoxin (TTX) and CoCl2 respectively and were characterized by their pharmacology, kinetics and voltage dependence of activation and inactivation. In all cases, a combination of three currents accounted for the total outward calcium-independent K+ current: (i) a steady linear conductance; (ii) a voltage-gated transient current, I(A), and (iii) a voltage-gated sustained current, I(K). Both voltage-gated currents were affected by the application of 4-aminopyridine and tetraethylammonia (TEA): I(A) showed a greater sensitivity to 4-aminopyridine, while I(K) was more sensitive to TEA. Both voltage-gated currents were present throughout the developmental period examined; however, the percentage of retinal ganglion cells (RGCs) expressing I(A) showed a marked decline from 82% at E31 to 45% at postnatal ages. During this development period there was an increase in the density of the two voltage-gated and the linear conductance. Additionally, with maturation, significantly slower inactivation kinetics were observed for I(K). These findings, and our previous results dealing with maturational changes in the TTX-sensitive voltage-gated Na current, are related to the generation of excitability in developing retinal ganglion cells. Furthermore, the presence of cells with and without transient K+ conductance throughout development suggests that the different spiking patterns observed in RGC classes may be partially due to differences in their membrane properties.

AB - During ontogeny retinal ganglion cells manifest pronounced changes in excitable membrane properties. To further our understanding of the ionic conductances underlying such functional changes, the whole-cell voltage-clamp variation of the patch-clamp technique was used to record potassium currents in 220 ganglion cells isolated by blocking voltage-gated Na+ and Ca2+ currents with tetrodoxin (TTX) and CoCl2 respectively and were characterized by their pharmacology, kinetics and voltage dependence of activation and inactivation. In all cases, a combination of three currents accounted for the total outward calcium-independent K+ current: (i) a steady linear conductance; (ii) a voltage-gated transient current, I(A), and (iii) a voltage-gated sustained current, I(K). Both voltage-gated currents were affected by the application of 4-aminopyridine and tetraethylammonia (TEA): I(A) showed a greater sensitivity to 4-aminopyridine, while I(K) was more sensitive to TEA. Both voltage-gated currents were present throughout the developmental period examined; however, the percentage of retinal ganglion cells (RGCs) expressing I(A) showed a marked decline from 82% at E31 to 45% at postnatal ages. During this development period there was an increase in the density of the two voltage-gated and the linear conductance. Additionally, with maturation, significantly slower inactivation kinetics were observed for I(K). These findings, and our previous results dealing with maturational changes in the TTX-sensitive voltage-gated Na current, are related to the generation of excitability in developing retinal ganglion cells. Furthermore, the presence of cells with and without transient K+ conductance throughout development suggests that the different spiking patterns observed in RGC classes may be partially due to differences in their membrane properties.

KW - Development

KW - Ion channels

KW - Linear conductance

KW - Patch-clamp recordings

KW - Potassium currents

UR - http://www.scopus.com/inward/record.url?scp=0029034577&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0029034577&partnerID=8YFLogxK

U2 - 10.1111/j.1460-9568.1995.tb01151.x

DO - 10.1111/j.1460-9568.1995.tb01151.x

M3 - Article

C2 - 7551182

AN - SCOPUS:0029034577

VL - 7

SP - 1558

EP - 1568

JO - European Journal of Neuroscience

JF - European Journal of Neuroscience

SN - 0953-816X

IS - 7

ER -