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Sodium pump-mediated ATP:ADP exchange. The sided effects of sodium and potassium ions
Resealed human red cell ghosts containing caged ATP (Kaplan et al., 1978) and [3H]ADP were irradiated at 340 nm. The photochemical release of free ATP initiated a rapid transphosphorylation reaction (ATP:ADP exchange), a component of which is inhibited by ouabain. The reaction rate was measured by f...
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Lenguaje: | English |
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The Rockefeller University Press
1982
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2228649/ https://www.ncbi.nlm.nih.gov/pubmed/6294224 |
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collection | PubMed |
description | Resealed human red cell ghosts containing caged ATP (Kaplan et al., 1978) and [3H]ADP were irradiated at 340 nm. The photochemical release of free ATP initiated a rapid transphosphorylation reaction (ATP:ADP exchange), a component of which is inhibited by ouabain. The reaction rate was measured by following the rate of appearance of [3H]ATP. The sodium pump-mediated ATP:ADP exchange reaction showed high-affinity stimulation by Mg ions (less than 10 microM) and was inhibited at higher levels. At optimal [Mg], extracellular Na (Nao) had a biphasic effect. Nao progressively inhibited the reaction rate between 0 and 10 mM and stimulated at higher levels. Intracellular Na (Nai) activated the reaction; the rate was maximal when Nai was 1 mM and remained unaltered up to 115 mM Nai at constant Nao. Extracellular K ions (Ko) inhibited the reaction; at high Nao, half-maximal inhibition was observed with 0.9 mM Ko. Lio inhibited the exchange rate with a lower affinity than Ko; half-maximal inhibition was produced by approximately 50 mM Lio. Intracellular K ions were without dramatic effect on the reaction rate in the concentration range where Ko inhibited completely. The relationship between these observations and previous studies on porous preparations is discussed, as well as the extent to which these observations support the hypothesis that the sodium pump-mediated ATP:ADP exchange reaction accompanies the Na:Na exchange transport mode of the sodium pump. |
format | Text |
id | pubmed-2228649 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1982 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-22286492008-04-23 Sodium pump-mediated ATP:ADP exchange. The sided effects of sodium and potassium ions J Gen Physiol Articles Resealed human red cell ghosts containing caged ATP (Kaplan et al., 1978) and [3H]ADP were irradiated at 340 nm. The photochemical release of free ATP initiated a rapid transphosphorylation reaction (ATP:ADP exchange), a component of which is inhibited by ouabain. The reaction rate was measured by following the rate of appearance of [3H]ATP. The sodium pump-mediated ATP:ADP exchange reaction showed high-affinity stimulation by Mg ions (less than 10 microM) and was inhibited at higher levels. At optimal [Mg], extracellular Na (Nao) had a biphasic effect. Nao progressively inhibited the reaction rate between 0 and 10 mM and stimulated at higher levels. Intracellular Na (Nai) activated the reaction; the rate was maximal when Nai was 1 mM and remained unaltered up to 115 mM Nai at constant Nao. Extracellular K ions (Ko) inhibited the reaction; at high Nao, half-maximal inhibition was observed with 0.9 mM Ko. Lio inhibited the exchange rate with a lower affinity than Ko; half-maximal inhibition was produced by approximately 50 mM Lio. Intracellular K ions were without dramatic effect on the reaction rate in the concentration range where Ko inhibited completely. The relationship between these observations and previous studies on porous preparations is discussed, as well as the extent to which these observations support the hypothesis that the sodium pump-mediated ATP:ADP exchange reaction accompanies the Na:Na exchange transport mode of the sodium pump. The Rockefeller University Press 1982-12-01 /pmc/articles/PMC2228649/ /pubmed/6294224 Text en 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 | Articles Sodium pump-mediated ATP:ADP exchange. The sided effects of sodium and potassium ions |
title | Sodium pump-mediated ATP:ADP exchange. The sided effects of sodium and potassium ions |
title_full | Sodium pump-mediated ATP:ADP exchange. The sided effects of sodium and potassium ions |
title_fullStr | Sodium pump-mediated ATP:ADP exchange. The sided effects of sodium and potassium ions |
title_full_unstemmed | Sodium pump-mediated ATP:ADP exchange. The sided effects of sodium and potassium ions |
title_short | Sodium pump-mediated ATP:ADP exchange. The sided effects of sodium and potassium ions |
title_sort | sodium pump-mediated atp:adp exchange. the sided effects of sodium and potassium ions |
topic | Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2228649/ https://www.ncbi.nlm.nih.gov/pubmed/6294224 |