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Calcium-activated conductance in skate electroreceptors: voltage clamp experiments
Voltage clamp experiments allow further characterization of the calcium- dependent repolarizing process in skate electroreceptor epithelium. Four current components are described: a prolonged capacity current, a leakage current, an early active current which flows inward across the lumenal membranes...
Formato: | Texto |
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Lenguaje: | English |
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The Rockefeller University Press
1977
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2215014/ https://www.ncbi.nlm.nih.gov/pubmed/402438 |
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collection | PubMed |
description | Voltage clamp experiments allow further characterization of the calcium- dependent repolarizing process in skate electroreceptor epithelium. Four current components are described: a prolonged capacity current, a leakage current, an early active current which flows inward across the lumenal membranes of the receptor cells, and a late current which flows outward. The leakage and capacity currents are linear and may be substracted from the total current, giving net active currents. The early active current is carried by calcium and does not undergo inactivation for at least several seconds. When large stimuli exceed the reversal potential for the early calcium current, the late current is suppressed. Reduction of the ionized calcium concentration in the lumen lowers the reversal potential for the early current and the suppression potential for the late current by the same amount. We conclude that the late current is initiated by a calcium influx into the cytoplasm. During pulses of moderate duration, activation of the late current does not begin until a fixed amount of calcium has entered the receptor cells. The required amount of calcium is reduced if a recent calcium influx has occurred. We suggest that the calcium- activated outward current is mediated by a distinct macromolecule that is insensitive to voltage. Such macromolecules are likely to have an important role in the regulation of electrical activity in excitable cells. |
format | Text |
id | pubmed-2215014 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1977 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-22150142008-04-23 Calcium-activated conductance in skate electroreceptors: voltage clamp experiments J Gen Physiol Articles Voltage clamp experiments allow further characterization of the calcium- dependent repolarizing process in skate electroreceptor epithelium. Four current components are described: a prolonged capacity current, a leakage current, an early active current which flows inward across the lumenal membranes of the receptor cells, and a late current which flows outward. The leakage and capacity currents are linear and may be substracted from the total current, giving net active currents. The early active current is carried by calcium and does not undergo inactivation for at least several seconds. When large stimuli exceed the reversal potential for the early calcium current, the late current is suppressed. Reduction of the ionized calcium concentration in the lumen lowers the reversal potential for the early current and the suppression potential for the late current by the same amount. We conclude that the late current is initiated by a calcium influx into the cytoplasm. During pulses of moderate duration, activation of the late current does not begin until a fixed amount of calcium has entered the receptor cells. The required amount of calcium is reduced if a recent calcium influx has occurred. We suggest that the calcium- activated outward current is mediated by a distinct macromolecule that is insensitive to voltage. Such macromolecules are likely to have an important role in the regulation of electrical activity in excitable cells. The Rockefeller University Press 1977-02-01 /pmc/articles/PMC2215014/ /pubmed/402438 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 Calcium-activated conductance in skate electroreceptors: voltage clamp experiments |
title | Calcium-activated conductance in skate electroreceptors: voltage clamp experiments |
title_full | Calcium-activated conductance in skate electroreceptors: voltage clamp experiments |
title_fullStr | Calcium-activated conductance in skate electroreceptors: voltage clamp experiments |
title_full_unstemmed | Calcium-activated conductance in skate electroreceptors: voltage clamp experiments |
title_short | Calcium-activated conductance in skate electroreceptors: voltage clamp experiments |
title_sort | calcium-activated conductance in skate electroreceptors: voltage clamp experiments |
topic | Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2215014/ https://www.ncbi.nlm.nih.gov/pubmed/402438 |