Cargando…
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...
Autores principales: | , |
---|---|
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 |
_version_ | 1782149671567753216 |
---|---|
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. |
format | Text |
id | pubmed-2225631 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1966 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
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 |
work_keys_str_mv | AT bennettmichaelvl analysisofdepolarizingandhyperpolarizinginactivationresponsesingymnotidelectroplaques AT grundfestharry analysisofdepolarizingandhyperpolarizinginactivationresponsesingymnotidelectroplaques |