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A New Proposal for the Action of Vasopressin, Based on Studies of a Complex Synthetic Membrane
The total osmotic flow of water across cell membranes generally exceeds diffusional flow measured with labeled water. The ratio of osmotic to diffusional flow has been widely used as a basis for the calculation of the radius of pores in the membrane, assuming Poiseuille flow of water through the por...
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Formato: | Texto |
Lenguaje: | English |
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The Rockefeller University Press
1968
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2201137/ https://www.ncbi.nlm.nih.gov/pubmed/5648834 |
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author | Hays, Richard M. |
author_facet | Hays, Richard M. |
author_sort | Hays, Richard M. |
collection | PubMed |
description | The total osmotic flow of water across cell membranes generally exceeds diffusional flow measured with labeled water. The ratio of osmotic to diffusional flow has been widely used as a basis for the calculation of the radius of pores in the membrane, assuming Poiseuille flow of water through the pores. An important assumption underlying this calculation is that both osmotic and diffusional flow are rate-limited by the same barrier in the membrane. Studies employing a complex synthetic membrane show, however, that osmotic flow can be limited by one barrier (thin, dense barrier), and the rate of diffusion of isotopic water by a second (thick, porous) barrier in series with the first. Calculation of a pore radius is meaningless under these conditions, greatly overestimating the size of the pores determining osmotic flow. On the basis of these results, the estimation of pore radius in biological membranes is reassessed. It is proposed that vasopressin acts by greatly increasing the rate of diffusion of water across an outer barrier of the membrane, with little or no accompanying increase in pore size. |
format | Text |
id | pubmed-2201137 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1968 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-22011372008-04-23 A New Proposal for the Action of Vasopressin, Based on Studies of a Complex Synthetic Membrane Hays, Richard M. J Gen Physiol Article The total osmotic flow of water across cell membranes generally exceeds diffusional flow measured with labeled water. The ratio of osmotic to diffusional flow has been widely used as a basis for the calculation of the radius of pores in the membrane, assuming Poiseuille flow of water through the pores. An important assumption underlying this calculation is that both osmotic and diffusional flow are rate-limited by the same barrier in the membrane. Studies employing a complex synthetic membrane show, however, that osmotic flow can be limited by one barrier (thin, dense barrier), and the rate of diffusion of isotopic water by a second (thick, porous) barrier in series with the first. Calculation of a pore radius is meaningless under these conditions, greatly overestimating the size of the pores determining osmotic flow. On the basis of these results, the estimation of pore radius in biological membranes is reassessed. It is proposed that vasopressin acts by greatly increasing the rate of diffusion of water across an outer barrier of the membrane, with little or no accompanying increase in pore size. The Rockefeller University Press 1968-03-01 /pmc/articles/PMC2201137/ /pubmed/5648834 Text en Copyright © 1968 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 Hays, Richard M. A New Proposal for the Action of Vasopressin, Based on Studies of a Complex Synthetic Membrane |
title | A New Proposal for the Action of Vasopressin, Based on Studies of a Complex Synthetic Membrane |
title_full | A New Proposal for the Action of Vasopressin, Based on Studies of a Complex Synthetic Membrane |
title_fullStr | A New Proposal for the Action of Vasopressin, Based on Studies of a Complex Synthetic Membrane |
title_full_unstemmed | A New Proposal for the Action of Vasopressin, Based on Studies of a Complex Synthetic Membrane |
title_short | A New Proposal for the Action of Vasopressin, Based on Studies of a Complex Synthetic Membrane |
title_sort | new proposal for the action of vasopressin, based on studies of a complex synthetic membrane |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2201137/ https://www.ncbi.nlm.nih.gov/pubmed/5648834 |
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