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Exchange Diffusion Effect and Euryhalinity in Teleosts

The sea water (SW)-adapted euryhaline Platichthys flesus, and the marine Serranus exchange about 50% of their internal sodium with the external sodium per hour. This rate of exchange decreases with decreasing salinity of the adaptation medium. When the flounder is transferred from SW to FW an instan...

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Detalles Bibliográficos
Autores principales: Motais, R., Garcia, F., Maetz, Romeu J.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1966
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2225658/
https://www.ncbi.nlm.nih.gov/pubmed/11526837
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author Motais, R.
Garcia, F.
Maetz, Romeu J.
author_facet Motais, R.
Garcia, F.
Maetz, Romeu J.
author_sort Motais, R.
collection PubMed
description The sea water (SW)-adapted euryhaline Platichthys flesus, and the marine Serranus exchange about 50% of their internal sodium with the external sodium per hour. This rate of exchange decreases with decreasing salinity of the adaptation medium. When the flounder is transferred from SW to FW an instantaneous 90% reduction of the Na and Cl outflux is observed. About 30 min later a second, progressive, reduction occurs. The outflux reductions appear to result from two types of regulatory mechanisms reducing gill permeability and preventing excessive salt loss. The first reduction corresponds to independent "Na- and Cl-free effects" as shown by transfers to artificial media containing either Na or Cl with an impermeant co-ion. The pattern of simultaneous rapid variations of Na influx and outflux for a range of salinity changes in flounder adapted to SW, ½ SW, or ¼ SW has been studied. The data are compatible with the hypothesis of an exchange diffusion mechanism characterized by a coupling of both unidirectional fluxes. The affinity of the exchange diffusion carrier for sodium has been measured (K(m) ≃ 400 mM). The delayed reduction would result from a progressive diminution of the quantity of carrier available but without modification of its affinity for sodium. When the stenohaline marine perch is transferred from SW to FW, a 40% reduction of the outflux is observed. But it is not the result of an exchange diffusion effect as it is related to the external osmolarity change and not to the NaCl concentration change. Furthermore no delayed reduction is observed after transfer into FW. This transfer is accompanied by a heavy loss of electrolytes resulting in a rapid decline of the plasma electrolyte level and death. A comparative survey of the relative importance of these regulatory mechanisms has been made.
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spelling pubmed-22256582008-04-23 Exchange Diffusion Effect and Euryhalinity in Teleosts Motais, R. Garcia, F. Maetz, Romeu J. J Gen Physiol Article The sea water (SW)-adapted euryhaline Platichthys flesus, and the marine Serranus exchange about 50% of their internal sodium with the external sodium per hour. This rate of exchange decreases with decreasing salinity of the adaptation medium. When the flounder is transferred from SW to FW an instantaneous 90% reduction of the Na and Cl outflux is observed. About 30 min later a second, progressive, reduction occurs. The outflux reductions appear to result from two types of regulatory mechanisms reducing gill permeability and preventing excessive salt loss. The first reduction corresponds to independent "Na- and Cl-free effects" as shown by transfers to artificial media containing either Na or Cl with an impermeant co-ion. The pattern of simultaneous rapid variations of Na influx and outflux for a range of salinity changes in flounder adapted to SW, ½ SW, or ¼ SW has been studied. The data are compatible with the hypothesis of an exchange diffusion mechanism characterized by a coupling of both unidirectional fluxes. The affinity of the exchange diffusion carrier for sodium has been measured (K(m) ≃ 400 mM). The delayed reduction would result from a progressive diminution of the quantity of carrier available but without modification of its affinity for sodium. When the stenohaline marine perch is transferred from SW to FW, a 40% reduction of the outflux is observed. But it is not the result of an exchange diffusion effect as it is related to the external osmolarity change and not to the NaCl concentration change. Furthermore no delayed reduction is observed after transfer into FW. This transfer is accompanied by a heavy loss of electrolytes resulting in a rapid decline of the plasma electrolyte level and death. A comparative survey of the relative importance of these regulatory mechanisms has been made. The Rockefeller University Press 1966-11-01 /pmc/articles/PMC2225658/ /pubmed/11526837 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
Motais, R.
Garcia, F.
Maetz, Romeu J.
Exchange Diffusion Effect and Euryhalinity in Teleosts
title Exchange Diffusion Effect and Euryhalinity in Teleosts
title_full Exchange Diffusion Effect and Euryhalinity in Teleosts
title_fullStr Exchange Diffusion Effect and Euryhalinity in Teleosts
title_full_unstemmed Exchange Diffusion Effect and Euryhalinity in Teleosts
title_short Exchange Diffusion Effect and Euryhalinity in Teleosts
title_sort exchange diffusion effect and euryhalinity in teleosts
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2225658/
https://www.ncbi.nlm.nih.gov/pubmed/11526837
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