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Electrical Inexcitability of the Frog Neuromuscular Synapse

Frog muscle endplates were explored with an extracellular microelectrode. An intracellular microelectrode nearby simultaneously monitored invasion of the endplate by a spike directly evoked by a third microelectrode placed away from the endplate in the same fiber. External positivities were seen onl...

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Detalles Bibliográficos
Autor principal: Werman, Robert
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1963
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2195273/
https://www.ncbi.nlm.nih.gov/pubmed/14000008
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author Werman, Robert
author_facet Werman, Robert
author_sort Werman, Robert
collection PubMed
description Frog muscle endplates were explored with an extracellular microelectrode. An intracellular microelectrode nearby simultaneously monitored invasion of the endplate by a spike directly evoked by a third microelectrode placed away from the endplate in the same fiber. External positivities were seen only at sites generating miniature endplate potentials. The external positivity reached a maximum prior to the internally recorded potential and was followed by a small late negativity. Small movements away from active synaptic sites resulted in positive-negative-positive potential sequences characteristic of activity and propagation. Since the external potential is a function of membrane current, the absence of negativity associated with the rising phase of the spike indicates the absence of inward current at synaptic sites. Thus, the synaptic membrane appears not to be excited by a depolarization of the magnitude of an action potential. In an Appendix it is shown that the late negativity and earlier maximum of the external potential can be accounted for by capacitative current through passive membrane.
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spelling pubmed-21952732008-04-23 Electrical Inexcitability of the Frog Neuromuscular Synapse Werman, Robert J Gen Physiol Article Frog muscle endplates were explored with an extracellular microelectrode. An intracellular microelectrode nearby simultaneously monitored invasion of the endplate by a spike directly evoked by a third microelectrode placed away from the endplate in the same fiber. External positivities were seen only at sites generating miniature endplate potentials. The external positivity reached a maximum prior to the internally recorded potential and was followed by a small late negativity. Small movements away from active synaptic sites resulted in positive-negative-positive potential sequences characteristic of activity and propagation. Since the external potential is a function of membrane current, the absence of negativity associated with the rising phase of the spike indicates the absence of inward current at synaptic sites. Thus, the synaptic membrane appears not to be excited by a depolarization of the magnitude of an action potential. In an Appendix it is shown that the late negativity and earlier maximum of the external potential can be accounted for by capacitative current through passive membrane. The Rockefeller University Press 1963-01-01 /pmc/articles/PMC2195273/ /pubmed/14000008 Text en Copyright ©, 1963, by The Rockefeller Institute 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
Werman, Robert
Electrical Inexcitability of the Frog Neuromuscular Synapse
title Electrical Inexcitability of the Frog Neuromuscular Synapse
title_full Electrical Inexcitability of the Frog Neuromuscular Synapse
title_fullStr Electrical Inexcitability of the Frog Neuromuscular Synapse
title_full_unstemmed Electrical Inexcitability of the Frog Neuromuscular Synapse
title_short Electrical Inexcitability of the Frog Neuromuscular Synapse
title_sort electrical inexcitability of the frog neuromuscular synapse
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2195273/
https://www.ncbi.nlm.nih.gov/pubmed/14000008
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