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An Electrogenic Sodium Pump in Limulus Ventral Photoreceptor Cells

A hyperpolarization can be recorded intracellularly following either a single bright light stimulus or the intracellular injection of Na(+). This after-hyperpolarization is abolished by bathing in 5 x 10(-6) M strophanthidin or removal of extracellular K(+). Both treatments also lead to a small, rap...

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Detalles Bibliográficos
Autores principales: Brown, J. E., Lisman, J. E.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1972
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2203198/
https://www.ncbi.nlm.nih.gov/pubmed/5025747
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author Brown, J. E.
Lisman, J. E.
author_facet Brown, J. E.
Lisman, J. E.
author_sort Brown, J. E.
collection PubMed
description A hyperpolarization can be recorded intracellularly following either a single bright light stimulus or the intracellular injection of Na(+). This after-hyperpolarization is abolished by bathing in 5 x 10(-6) M strophanthidin or removal of extracellular K(+). Both treatments also lead to a small, rapid depolarization of the dark-adapted cell. When either treatment is prolonged, light responses can still be elicited, although with repetitive stimuli the responses are slowly and progressively diminished in size. The rate of diminution is greater for higher values of [Ca(++)](out); with [Ca(++)](out) = 0.1 mM, there is almost no progressive diminution of repetitive responses produced by either K(+)-free seawater or strophanthidin. We propose that an electrogenic Na(+) pump contributes directly to dark-adapted membrane voltage and also generates the after-hyperpolarizations, but does not directly generate the receptor potential. Inhibition of this pump leads to intracellular accumulation of sodium ions, which in turn leads to an increase in intracellular Ca(++) (provided there is sufficient extracellular Ca(++)). This increase in intracellular calcium probably accounts for the progressive decrease in the size of the receptor potential seen when the pump is inhibited.
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spelling pubmed-22031982008-04-23 An Electrogenic Sodium Pump in Limulus Ventral Photoreceptor Cells Brown, J. E. Lisman, J. E. J Gen Physiol Article A hyperpolarization can be recorded intracellularly following either a single bright light stimulus or the intracellular injection of Na(+). This after-hyperpolarization is abolished by bathing in 5 x 10(-6) M strophanthidin or removal of extracellular K(+). Both treatments also lead to a small, rapid depolarization of the dark-adapted cell. When either treatment is prolonged, light responses can still be elicited, although with repetitive stimuli the responses are slowly and progressively diminished in size. The rate of diminution is greater for higher values of [Ca(++)](out); with [Ca(++)](out) = 0.1 mM, there is almost no progressive diminution of repetitive responses produced by either K(+)-free seawater or strophanthidin. We propose that an electrogenic Na(+) pump contributes directly to dark-adapted membrane voltage and also generates the after-hyperpolarizations, but does not directly generate the receptor potential. Inhibition of this pump leads to intracellular accumulation of sodium ions, which in turn leads to an increase in intracellular Ca(++) (provided there is sufficient extracellular Ca(++)). This increase in intracellular calcium probably accounts for the progressive decrease in the size of the receptor potential seen when the pump is inhibited. The Rockefeller University Press 1972-06-01 /pmc/articles/PMC2203198/ /pubmed/5025747 Text en Copyright © 1972 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
Brown, J. E.
Lisman, J. E.
An Electrogenic Sodium Pump in Limulus Ventral Photoreceptor Cells
title An Electrogenic Sodium Pump in Limulus Ventral Photoreceptor Cells
title_full An Electrogenic Sodium Pump in Limulus Ventral Photoreceptor Cells
title_fullStr An Electrogenic Sodium Pump in Limulus Ventral Photoreceptor Cells
title_full_unstemmed An Electrogenic Sodium Pump in Limulus Ventral Photoreceptor Cells
title_short An Electrogenic Sodium Pump in Limulus Ventral Photoreceptor Cells
title_sort electrogenic sodium pump in limulus ventral photoreceptor cells
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2203198/
https://www.ncbi.nlm.nih.gov/pubmed/5025747
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