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Analysis of Depolarizing and Hyperpolarizing Inactivation Responses in Gymnotid Electroplaques

In electroplaques of several gymnotid fishes hyperpolarizing or depolarizing currents can evoke all-or-none responses that are due to increase in membrane resistance as much as 10- to 12-fold. During a response the emf of the membrane shifts little, if at all, when the cell either is at its normal r...

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Autores principales: Bennett, Michael V. L., Grundfest, Harry
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1966
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2225631/
https://www.ncbi.nlm.nih.gov/pubmed/5971025
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author Bennett, Michael V. L.
Grundfest, Harry
author_facet Bennett, Michael V. L.
Grundfest, Harry
author_sort Bennett, Michael V. L.
collection PubMed
description In electroplaques of several gymnotid fishes hyperpolarizing or depolarizing currents can evoke all-or-none responses that are due to increase in membrane resistance as much as 10- to 12-fold. During a response the emf of the membrane shifts little, if at all, when the cell either is at its normal resting potential, or is depolarized by increasing external K, and in the case of depolarizing responses when either Cl or an impermeant anion is present. Thus, the increase in resistance is due mainly, or perhaps entirely, to decrease in K permeability, termed depolarizing or hyperpolarizing K inactivation, respectively. In voltage clamp measurements the current-voltage relation shows a negative resistance region. This characteristic accounts for the all-or-none initiation and termination of the responses demonstrable in current clamp experiments. Depolarizing inactivation is initiated and reversed too rapidly to measure with present techniques in cells in high K. Both time courses are slowed in cells studied in normal Ringer's. Once established, the high resistance state is maintained as long as an outward current is applied. Hyperpolarizing inactivation occurs in normal Ringer's or with moderate excess K. Its onset is more rapid with stronger stimuli. During prolonged currents it is not maintained; i.e., there is a secondary increase in conductance. Hyperpolarizing inactivation responses exhibit a long refractory period, presumably because of persistence of this secondary increase in conductance.
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spelling pubmed-22256312008-04-23 Analysis of Depolarizing and Hyperpolarizing Inactivation Responses in Gymnotid Electroplaques Bennett, Michael V. L. Grundfest, Harry J Gen Physiol Article In electroplaques of several gymnotid fishes hyperpolarizing or depolarizing currents can evoke all-or-none responses that are due to increase in membrane resistance as much as 10- to 12-fold. During a response the emf of the membrane shifts little, if at all, when the cell either is at its normal resting potential, or is depolarized by increasing external K, and in the case of depolarizing responses when either Cl or an impermeant anion is present. Thus, the increase in resistance is due mainly, or perhaps entirely, to decrease in K permeability, termed depolarizing or hyperpolarizing K inactivation, respectively. In voltage clamp measurements the current-voltage relation shows a negative resistance region. This characteristic accounts for the all-or-none initiation and termination of the responses demonstrable in current clamp experiments. Depolarizing inactivation is initiated and reversed too rapidly to measure with present techniques in cells in high K. Both time courses are slowed in cells studied in normal Ringer's. Once established, the high resistance state is maintained as long as an outward current is applied. Hyperpolarizing inactivation occurs in normal Ringer's or with moderate excess K. Its onset is more rapid with stronger stimuli. During prolonged currents it is not maintained; i.e., there is a secondary increase in conductance. Hyperpolarizing inactivation responses exhibit a long refractory period, presumably because of persistence of this secondary increase in conductance. The Rockefeller University Press 1966-09-01 /pmc/articles/PMC2225631/ /pubmed/5971025 Text en Copyright © 1967 by The Rockefeller University Press This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Article
Bennett, Michael V. L.
Grundfest, Harry
Analysis of Depolarizing and Hyperpolarizing Inactivation Responses in Gymnotid Electroplaques
title Analysis of Depolarizing and Hyperpolarizing Inactivation Responses in Gymnotid Electroplaques
title_full Analysis of Depolarizing and Hyperpolarizing Inactivation Responses in Gymnotid Electroplaques
title_fullStr Analysis of Depolarizing and Hyperpolarizing Inactivation Responses in Gymnotid Electroplaques
title_full_unstemmed Analysis of Depolarizing and Hyperpolarizing Inactivation Responses in Gymnotid Electroplaques
title_short Analysis of Depolarizing and Hyperpolarizing Inactivation Responses in Gymnotid Electroplaques
title_sort analysis of depolarizing and hyperpolarizing inactivation responses in gymnotid electroplaques
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2225631/
https://www.ncbi.nlm.nih.gov/pubmed/5971025
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