K+-evoked Müller cell depolarization generates b-wave of electroretinogram in toad retina

Rong Wen, Burks Oakley

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

We tested the hypothesis that a light-evoked increase in [K+]o produces a depolarization of the Müller cell membrane, which in turn generates the electroretinogram b-wave current. Using Bufo marinus isolated retinas and K+-selective microelectrodes, we recorded two distinct light-evoked increases in extracellular K+ concentration: one in the inner plexiform layer and the other near the outer plexiform layer; the "distal" K+ increase was found over only 10-μm depth and had a maximum amplitude of 0.3 mM. We also recorded the electroretinogram and the light-evoked responses of rods and Müller cells. After correction for the response time of the K+-selective microelectrode, the waveforms of all three of these responses were almost exactly as predicted by an earlier computer simulation of the K+/Müller cell hypothesis of the b-wave by Newman and Odette [Newman, E. A. & Odette, L. L. (1984) J. Neurophysiol. 51, 164-182]. The distal K+ increase and the b-wave varied in a similar manner as a function of stimulus irradiance. Superfusion with 0.2 mM Ba2+ attenuated both the Müller cell depolarization and the b-wave by ≈65% but had no significant effect upon the distal K+ increase. Because Ba2+ reduces K+ conductance of Müller cells, these results are very strong support of the K+/Müller cell hypothesis of the origin of the electroretinogram b-wave; the light-evoked increase in extracellular potassium concentration still is present during superfusion with Ba2+, but the K+-evoked Müller cell depolarization and the b-wave are decreased in amplitude because Müller cell K+ conductance is reduced.

Original languageEnglish
Pages (from-to)2117-2121
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume87
Issue number6
StatePublished - Mar 1 1990
Externally publishedYes

Fingerprint

Anura
Retina
Light
Microelectrodes
Bufo marinus
Computer Simulation
Reaction Time
Potassium
Cell Membrane

Keywords

  • Barium
  • K-selective microelectrode
  • Potassium conductance

ASJC Scopus subject areas

  • Genetics
  • General

Cite this

@article{23e39c7a34084a89a79f4abb3c924315,
title = "K+-evoked M{\"u}ller cell depolarization generates b-wave of electroretinogram in toad retina",
abstract = "We tested the hypothesis that a light-evoked increase in [K+]o produces a depolarization of the M{\"u}ller cell membrane, which in turn generates the electroretinogram b-wave current. Using Bufo marinus isolated retinas and K+-selective microelectrodes, we recorded two distinct light-evoked increases in extracellular K+ concentration: one in the inner plexiform layer and the other near the outer plexiform layer; the {"}distal{"} K+ increase was found over only 10-μm depth and had a maximum amplitude of 0.3 mM. We also recorded the electroretinogram and the light-evoked responses of rods and M{\"u}ller cells. After correction for the response time of the K+-selective microelectrode, the waveforms of all three of these responses were almost exactly as predicted by an earlier computer simulation of the K+/M{\"u}ller cell hypothesis of the b-wave by Newman and Odette [Newman, E. A. & Odette, L. L. (1984) J. Neurophysiol. 51, 164-182]. The distal K+ increase and the b-wave varied in a similar manner as a function of stimulus irradiance. Superfusion with 0.2 mM Ba2+ attenuated both the M{\"u}ller cell depolarization and the b-wave by ≈65{\%} but had no significant effect upon the distal K+ increase. Because Ba2+ reduces K+ conductance of M{\"u}ller cells, these results are very strong support of the K+/M{\"u}ller cell hypothesis of the origin of the electroretinogram b-wave; the light-evoked increase in extracellular potassium concentration still is present during superfusion with Ba2+, but the K+-evoked M{\"u}ller cell depolarization and the b-wave are decreased in amplitude because M{\"u}ller cell K+ conductance is reduced.",
keywords = "Barium, K-selective microelectrode, Potassium conductance",
author = "Rong Wen and Burks Oakley",
year = "1990",
month = "3",
day = "1",
language = "English",
volume = "87",
pages = "2117--2121",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
number = "6",

}

TY - JOUR

T1 - K+-evoked Müller cell depolarization generates b-wave of electroretinogram in toad retina

AU - Wen, Rong

AU - Oakley, Burks

PY - 1990/3/1

Y1 - 1990/3/1

N2 - We tested the hypothesis that a light-evoked increase in [K+]o produces a depolarization of the Müller cell membrane, which in turn generates the electroretinogram b-wave current. Using Bufo marinus isolated retinas and K+-selective microelectrodes, we recorded two distinct light-evoked increases in extracellular K+ concentration: one in the inner plexiform layer and the other near the outer plexiform layer; the "distal" K+ increase was found over only 10-μm depth and had a maximum amplitude of 0.3 mM. We also recorded the electroretinogram and the light-evoked responses of rods and Müller cells. After correction for the response time of the K+-selective microelectrode, the waveforms of all three of these responses were almost exactly as predicted by an earlier computer simulation of the K+/Müller cell hypothesis of the b-wave by Newman and Odette [Newman, E. A. & Odette, L. L. (1984) J. Neurophysiol. 51, 164-182]. The distal K+ increase and the b-wave varied in a similar manner as a function of stimulus irradiance. Superfusion with 0.2 mM Ba2+ attenuated both the Müller cell depolarization and the b-wave by ≈65% but had no significant effect upon the distal K+ increase. Because Ba2+ reduces K+ conductance of Müller cells, these results are very strong support of the K+/Müller cell hypothesis of the origin of the electroretinogram b-wave; the light-evoked increase in extracellular potassium concentration still is present during superfusion with Ba2+, but the K+-evoked Müller cell depolarization and the b-wave are decreased in amplitude because Müller cell K+ conductance is reduced.

AB - We tested the hypothesis that a light-evoked increase in [K+]o produces a depolarization of the Müller cell membrane, which in turn generates the electroretinogram b-wave current. Using Bufo marinus isolated retinas and K+-selective microelectrodes, we recorded two distinct light-evoked increases in extracellular K+ concentration: one in the inner plexiform layer and the other near the outer plexiform layer; the "distal" K+ increase was found over only 10-μm depth and had a maximum amplitude of 0.3 mM. We also recorded the electroretinogram and the light-evoked responses of rods and Müller cells. After correction for the response time of the K+-selective microelectrode, the waveforms of all three of these responses were almost exactly as predicted by an earlier computer simulation of the K+/Müller cell hypothesis of the b-wave by Newman and Odette [Newman, E. A. & Odette, L. L. (1984) J. Neurophysiol. 51, 164-182]. The distal K+ increase and the b-wave varied in a similar manner as a function of stimulus irradiance. Superfusion with 0.2 mM Ba2+ attenuated both the Müller cell depolarization and the b-wave by ≈65% but had no significant effect upon the distal K+ increase. Because Ba2+ reduces K+ conductance of Müller cells, these results are very strong support of the K+/Müller cell hypothesis of the origin of the electroretinogram b-wave; the light-evoked increase in extracellular potassium concentration still is present during superfusion with Ba2+, but the K+-evoked Müller cell depolarization and the b-wave are decreased in amplitude because Müller cell K+ conductance is reduced.

KW - Barium

KW - K-selective microelectrode

KW - Potassium conductance

UR - http://www.scopus.com/inward/record.url?scp=0025192329&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0025192329&partnerID=8YFLogxK

M3 - Article

C2 - 2107544

AN - SCOPUS:0025192329

VL - 87

SP - 2117

EP - 2121

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 6

ER -