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Basolateral K channels in an insect epithelium. Channel density, conductance, and block by barium
K channels in the basolateral membrane of insect hindgut were studied using current fluctuation analysis and microelectrodes. Locust recta were mounted in Ussing-type chambers containing Cl-free saline and cyclic AMP (cAMP). A transepithelial K current was induced by raising serosal [K] under short-...
Autores principales: | , , , |
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Formato: | Texto |
Lenguaje: | English |
Publicado: |
The Rockefeller University Press
1986
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2217614/ https://www.ncbi.nlm.nih.gov/pubmed/2420918 |
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author | Hanrahan, JW Wills, NK Phillips, JE Lewis, SA |
author_facet | Hanrahan, JW Wills, NK Phillips, JE Lewis, SA |
author_sort | Hanrahan, JW |
collection | PubMed |
description | K channels in the basolateral membrane of insect hindgut were studied using current fluctuation analysis and microelectrodes. Locust recta were mounted in Ussing-type chambers containing Cl-free saline and cyclic AMP (cAMP). A transepithelial K current was induced by raising serosal [K] under short-circuit conditions. Adding Ba to the mucosal (luminal) side under these conditions had no effect; however, serosal Ba reversibly inhibited the short-circuit current (Isc), increased transepithelial resistance (Rt), and added a Lorentzian component to power density spectra of the Isc. A nonlinear relationship between corner frequency and serosal [Ba] was observed, which suggests that the rate constant for Ba association with basolateral channels increased as [Ba] was elevated. Microelectrode experiments revealed that the basolateral membrane hyperpolarized when Ba was added: this change in membrane potential could explain the nonlinearity of the 2 pi fc vs. [Ba] relationship if external Ba sensed about three-quarters of the basolateral membrane field. Conventional microelectrodes were used to determine the correspondence between transepithelially measured current noise and basolateral membrane conductance fluctuations, and ion-sensitive microelectrodes were used to measure intracellular K activity (acK). From the relationship between the net electrochemical potential for K across the basolateral membrane and the single channel current calculated from noise analysis, we estimate that the conductance of basolateral K channels is approximately 60 pS, and that there are approximately 180 million channels per square centimeter of tissue area. |
format | Text |
id | pubmed-2217614 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1986 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-22176142008-04-23 Basolateral K channels in an insect epithelium. Channel density, conductance, and block by barium Hanrahan, JW Wills, NK Phillips, JE Lewis, SA J Gen Physiol Articles K channels in the basolateral membrane of insect hindgut were studied using current fluctuation analysis and microelectrodes. Locust recta were mounted in Ussing-type chambers containing Cl-free saline and cyclic AMP (cAMP). A transepithelial K current was induced by raising serosal [K] under short-circuit conditions. Adding Ba to the mucosal (luminal) side under these conditions had no effect; however, serosal Ba reversibly inhibited the short-circuit current (Isc), increased transepithelial resistance (Rt), and added a Lorentzian component to power density spectra of the Isc. A nonlinear relationship between corner frequency and serosal [Ba] was observed, which suggests that the rate constant for Ba association with basolateral channels increased as [Ba] was elevated. Microelectrode experiments revealed that the basolateral membrane hyperpolarized when Ba was added: this change in membrane potential could explain the nonlinearity of the 2 pi fc vs. [Ba] relationship if external Ba sensed about three-quarters of the basolateral membrane field. Conventional microelectrodes were used to determine the correspondence between transepithelially measured current noise and basolateral membrane conductance fluctuations, and ion-sensitive microelectrodes were used to measure intracellular K activity (acK). From the relationship between the net electrochemical potential for K across the basolateral membrane and the single channel current calculated from noise analysis, we estimate that the conductance of basolateral K channels is approximately 60 pS, and that there are approximately 180 million channels per square centimeter of tissue area. The Rockefeller University Press 1986-03-01 /pmc/articles/PMC2217614/ /pubmed/2420918 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 Hanrahan, JW Wills, NK Phillips, JE Lewis, SA Basolateral K channels in an insect epithelium. Channel density, conductance, and block by barium |
title | Basolateral K channels in an insect epithelium. Channel density, conductance, and block by barium |
title_full | Basolateral K channels in an insect epithelium. Channel density, conductance, and block by barium |
title_fullStr | Basolateral K channels in an insect epithelium. Channel density, conductance, and block by barium |
title_full_unstemmed | Basolateral K channels in an insect epithelium. Channel density, conductance, and block by barium |
title_short | Basolateral K channels in an insect epithelium. Channel density, conductance, and block by barium |
title_sort | basolateral k channels in an insect epithelium. channel density, conductance, and block by barium |
topic | Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2217614/ https://www.ncbi.nlm.nih.gov/pubmed/2420918 |
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