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Dependence of ionized and total Ca in squid axons on Nao-free or high- Ko conditions
The level of intracellular Ca in squid axons (both ionized and total Ca) was studied as a function of the experimental variables [Na]i, [Na]o, pHi, cyanide, and depolarization. Ionized Ca was measured by following the light emission of aequorin while total Ca was measured by the atomic absorption an...
Formato: | Texto |
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Lenguaje: | English |
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The Rockefeller University Press
1986
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2217132/ https://www.ncbi.nlm.nih.gov/pubmed/3950575 |
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collection | PubMed |
description | The level of intracellular Ca in squid axons (both ionized and total Ca) was studied as a function of the experimental variables [Na]i, [Na]o, pHi, cyanide, and depolarization. Ionized Ca was measured by following the light emission of aequorin while total Ca was measured by the atomic absorption analysis of samples of axoplasm. Aequorin glow is known to be increased either by the application of Nao-free solutions or by depolarization produced by external solutions containing greater than normal K concentrations. The present results show that if [Na]i is low, the depolarization that is brought about by solutions with elevated [K] leads to a resting light emission that is decreased rather than increased, as is the case when [Na]i is high. In axons where [Na]i is varied, a comparison of the increments in light emission produced by the application first of Na-free and then of high-K solutions shows that they have an identical dependence on [Na]i, with a half-activation of Ca entry produced by an [Na]i of 25-30 mM. Changes in pHi affect the aequorin signal produced by depolarization, with acidification reducing and alkanization increasing the response. Cyanide did not greatly affect the size of the signal resulting from either Nao removal or that from depolarization. |
format | Text |
id | pubmed-2217132 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1986 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-22171322008-04-23 Dependence of ionized and total Ca in squid axons on Nao-free or high- Ko conditions J Gen Physiol Articles The level of intracellular Ca in squid axons (both ionized and total Ca) was studied as a function of the experimental variables [Na]i, [Na]o, pHi, cyanide, and depolarization. Ionized Ca was measured by following the light emission of aequorin while total Ca was measured by the atomic absorption analysis of samples of axoplasm. Aequorin glow is known to be increased either by the application of Nao-free solutions or by depolarization produced by external solutions containing greater than normal K concentrations. The present results show that if [Na]i is low, the depolarization that is brought about by solutions with elevated [K] leads to a resting light emission that is decreased rather than increased, as is the case when [Na]i is high. In axons where [Na]i is varied, a comparison of the increments in light emission produced by the application first of Na-free and then of high-K solutions shows that they have an identical dependence on [Na]i, with a half-activation of Ca entry produced by an [Na]i of 25-30 mM. Changes in pHi affect the aequorin signal produced by depolarization, with acidification reducing and alkanization increasing the response. Cyanide did not greatly affect the size of the signal resulting from either Nao removal or that from depolarization. The Rockefeller University Press 1986-01-01 /pmc/articles/PMC2217132/ /pubmed/3950575 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 Dependence of ionized and total Ca in squid axons on Nao-free or high- Ko conditions |
title | Dependence of ionized and total Ca in squid axons on Nao-free or high- Ko conditions |
title_full | Dependence of ionized and total Ca in squid axons on Nao-free or high- Ko conditions |
title_fullStr | Dependence of ionized and total Ca in squid axons on Nao-free or high- Ko conditions |
title_full_unstemmed | Dependence of ionized and total Ca in squid axons on Nao-free or high- Ko conditions |
title_short | Dependence of ionized and total Ca in squid axons on Nao-free or high- Ko conditions |
title_sort | dependence of ionized and total ca in squid axons on nao-free or high- ko conditions |
topic | Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2217132/ https://www.ncbi.nlm.nih.gov/pubmed/3950575 |