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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-...

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Detalles Bibliográficos
Autores principales: Hanrahan, JW, Wills, NK, Phillips, JE, Lewis, SA
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1986
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.
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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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