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Temperature Dependence of Vasopressin Action on the Toad Bladder
Toad bladders were challenged with vasopressin at one temperature, fixed on the mucosa with 1% glutaraldehyde, and then subjected to an osmotic gradient at another temperature. Thus, the temperature dependence of vasopressin action on membrane permeability was distinguished from the temperature depe...
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Formato: | Texto |
Lenguaje: | English |
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The Rockefeller University Press
1972
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2203194/ https://www.ncbi.nlm.nih.gov/pubmed/4623851 |
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author | Eggena, Patrick |
author_facet | Eggena, Patrick |
author_sort | Eggena, Patrick |
collection | PubMed |
description | Toad bladders were challenged with vasopressin at one temperature, fixed on the mucosa with 1% glutaraldehyde, and then subjected to an osmotic gradient at another temperature. Thus, the temperature dependence of vasopressin action on membrane permeability was distinguished from the temperature dependence of osmotic water flux. As the temperature was raised from 20° to 38°C, there was a substantial increase in the velocity of vasopressin action, but osmotic flux was hardly affected. In this range of temperature the apparent energy of activation for net water movement across the bladder amounted to only 1.2 kcal/mole, a value well below the activation energy for bulk water viscosity. It is suggested that osmotic water flux takes place through narrow, nonpolar channels in the membrane. When the temperature was raised from 4° to 20°C, both vasopressin action as well as osmotic water flux were markedly enhanced. Activation energies for net water movement were now 8.5 kcal/mole (4°–9°C) and 4.1 kcal/mole (9°–20°C), indicating that the components of the aqueous channel undergo conformational changes as the temperature is lowered from 20°C. At 43°C bladder reactivity to vasopressin was lost, and irreversible changes in selective permeability were observed. The apparent energy of activation for net water movement across the denatured membrane was 6.6 kcal/mole. Approximately 1 µosmol of NaCl was exchanged for 1 µl of H(2)O across the denatured membrane. |
format | Text |
id | pubmed-2203194 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1972 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-22031942008-04-23 Temperature Dependence of Vasopressin Action on the Toad Bladder Eggena, Patrick J Gen Physiol Article Toad bladders were challenged with vasopressin at one temperature, fixed on the mucosa with 1% glutaraldehyde, and then subjected to an osmotic gradient at another temperature. Thus, the temperature dependence of vasopressin action on membrane permeability was distinguished from the temperature dependence of osmotic water flux. As the temperature was raised from 20° to 38°C, there was a substantial increase in the velocity of vasopressin action, but osmotic flux was hardly affected. In this range of temperature the apparent energy of activation for net water movement across the bladder amounted to only 1.2 kcal/mole, a value well below the activation energy for bulk water viscosity. It is suggested that osmotic water flux takes place through narrow, nonpolar channels in the membrane. When the temperature was raised from 4° to 20°C, both vasopressin action as well as osmotic water flux were markedly enhanced. Activation energies for net water movement were now 8.5 kcal/mole (4°–9°C) and 4.1 kcal/mole (9°–20°C), indicating that the components of the aqueous channel undergo conformational changes as the temperature is lowered from 20°C. At 43°C bladder reactivity to vasopressin was lost, and irreversible changes in selective permeability were observed. The apparent energy of activation for net water movement across the denatured membrane was 6.6 kcal/mole. Approximately 1 µosmol of NaCl was exchanged for 1 µl of H(2)O across the denatured membrane. The Rockefeller University Press 1972-05-01 /pmc/articles/PMC2203194/ /pubmed/4623851 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 Eggena, Patrick Temperature Dependence of Vasopressin Action on the Toad Bladder |
title | Temperature Dependence of Vasopressin Action on the Toad Bladder |
title_full | Temperature Dependence of Vasopressin Action on the Toad Bladder |
title_fullStr | Temperature Dependence of Vasopressin Action on the Toad Bladder |
title_full_unstemmed | Temperature Dependence of Vasopressin Action on the Toad Bladder |
title_short | Temperature Dependence of Vasopressin Action on the Toad Bladder |
title_sort | temperature dependence of vasopressin action on the toad bladder |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2203194/ https://www.ncbi.nlm.nih.gov/pubmed/4623851 |
work_keys_str_mv | AT eggenapatrick temperaturedependenceofvasopressinactiononthetoadbladder |