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Conductance Properties of Artificial Lipidic Membranes Containing a Proteolipid from Electrophorus : Response to cholinergic agents

Previous studies have shown that a special proteolipid extract from the electric organ of Electrophorus showed high affinity binding for acetylcholine and other cholinergic agents. This proteolipid has now been incorporated into ultrathin lipidic membranes, and the membrane resistance was studied. T...

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Autores principales: Parisi, Mario, Reader, Tomás A., de Robertis, Eduardo
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1972
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2226085/
https://www.ncbi.nlm.nih.gov/pubmed/4342352
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author Parisi, Mario
Reader, Tomás A.
de Robertis, Eduardo
author_facet Parisi, Mario
Reader, Tomás A.
de Robertis, Eduardo
author_sort Parisi, Mario
collection PubMed
description Previous studies have shown that a special proteolipid extract from the electric organ of Electrophorus showed high affinity binding for acetylcholine and other cholinergic agents. This proteolipid has now been incorporated into ultrathin lipidic membranes, and the membrane resistance was studied. The resistance decreased from 7.27 ± 0.82 x 10(5) ohm cm(2) in the control membrane to 1.83 x 10(5) ohm cm(2) with addition of 72 µg/ml proteolipid. The decrease in resistance followed a potential function of order four with the proteolipid concentration in the membrane-forming solution. The presence of this proteolipid determined some type of cationic selectivity which was not observed in the control. At a critical point of proteolipid concentration the conductance spontaneously fluctuated between two levels. The membrane current jumped from one state to another by way of single discrete steps, reminiscent of those obtained with the excitatory inducing material or the macrocyclic antibiotics. In membranes containing another proteolipid having no cholinergic binding properties, the increase in conductance was smaller, and had a linear function with the concentration. In this case the "flip flop" fluctuation and the cationic selectivity were not observed. The membranes containing the cholinergic proteolipid reacted to the addition of acetylcholine by a rapid and transient increase in conductance that was considerably reduced or abolished by a previous application of d-tubocurarine. These membranes also interacted with other cholinergic agents, such as gallamine triethiodide, hexamethonium, and α-bungarotoxin. These results suggest that this special proteolipid, when added to the artificial membranes, induces a "chemical excitability" toward cholinergic ligands.
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spelling pubmed-22260852008-04-23 Conductance Properties of Artificial Lipidic Membranes Containing a Proteolipid from Electrophorus : Response to cholinergic agents Parisi, Mario Reader, Tomás A. de Robertis, Eduardo J Gen Physiol Article Previous studies have shown that a special proteolipid extract from the electric organ of Electrophorus showed high affinity binding for acetylcholine and other cholinergic agents. This proteolipid has now been incorporated into ultrathin lipidic membranes, and the membrane resistance was studied. The resistance decreased from 7.27 ± 0.82 x 10(5) ohm cm(2) in the control membrane to 1.83 x 10(5) ohm cm(2) with addition of 72 µg/ml proteolipid. The decrease in resistance followed a potential function of order four with the proteolipid concentration in the membrane-forming solution. The presence of this proteolipid determined some type of cationic selectivity which was not observed in the control. At a critical point of proteolipid concentration the conductance spontaneously fluctuated between two levels. The membrane current jumped from one state to another by way of single discrete steps, reminiscent of those obtained with the excitatory inducing material or the macrocyclic antibiotics. In membranes containing another proteolipid having no cholinergic binding properties, the increase in conductance was smaller, and had a linear function with the concentration. In this case the "flip flop" fluctuation and the cationic selectivity were not observed. The membranes containing the cholinergic proteolipid reacted to the addition of acetylcholine by a rapid and transient increase in conductance that was considerably reduced or abolished by a previous application of d-tubocurarine. These membranes also interacted with other cholinergic agents, such as gallamine triethiodide, hexamethonium, and α-bungarotoxin. These results suggest that this special proteolipid, when added to the artificial membranes, induces a "chemical excitability" toward cholinergic ligands. The Rockefeller University Press 1972-10-01 /pmc/articles/PMC2226085/ /pubmed/4342352 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
Parisi, Mario
Reader, Tomás A.
de Robertis, Eduardo
Conductance Properties of Artificial Lipidic Membranes Containing a Proteolipid from Electrophorus : Response to cholinergic agents
title Conductance Properties of Artificial Lipidic Membranes Containing a Proteolipid from Electrophorus : Response to cholinergic agents
title_full Conductance Properties of Artificial Lipidic Membranes Containing a Proteolipid from Electrophorus : Response to cholinergic agents
title_fullStr Conductance Properties of Artificial Lipidic Membranes Containing a Proteolipid from Electrophorus : Response to cholinergic agents
title_full_unstemmed Conductance Properties of Artificial Lipidic Membranes Containing a Proteolipid from Electrophorus : Response to cholinergic agents
title_short Conductance Properties of Artificial Lipidic Membranes Containing a Proteolipid from Electrophorus : Response to cholinergic agents
title_sort conductance properties of artificial lipidic membranes containing a proteolipid from electrophorus : response to cholinergic agents
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2226085/
https://www.ncbi.nlm.nih.gov/pubmed/4342352
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