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Recording Sodium Self-Inhibition of Epithelial Sodium Channels Using Automated Electrophysiology in Xenopus Oocytes

  • The epithelial sodium channel (ENaC) is a key regulator of sodium homeostasis that contributes to blood pressure control. ENaC open probability is adjusted by extracellular sodium ions, a mechanism referred to as sodium self-inhibition (SSI). With a growing number of identified ENaC gene variants associated with hypertension, there is an increasing demand for medium- to high-throughput assays allowing the detection of alterations in ENaC activity and SSI. We evaluated a commercially available automated two-electrode voltage-clamp (TEVC) system that records transmembrane currents of ENaC-expressing Xenopus oocytes in 96-well microtiter plates. We employed guinea pig, human and Xenopus laevis ENaC orthologs that display specific magnitudes of SSI. While demonstrating some limitations over traditional TEVC systems with customized perfusion chambers, the automated TEVC system was able to detect the established SSI characteristics of the employed ENaC orthologs. We were able to confirm a reduced SSI in a gene variant, leading to C479R substitution in the human α-ENaC subunit that has been reported in Liddle syndrome. In conclusion, automated TEVC in Xenopus oocytes can detect SSI of ENaC orthologs and variants associated with hypertension. For precise mechanistic and kinetic analyses of SSI, optimization for faster solution exchange rates is recommended.

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Document Type:Article
Author:Rene Y. Lawong, Fabian May, Etang C. Etang, Philipp Vorrat, Jonas George, Julia Weder, Dagmar Kockler, Matthias Preller, Mike Althaus
Parent Title (English):Membranes
Article Number:529
Number of pages:11
Place of publication:Basel
Publishing Institution:Hochschule Bonn-Rhein-Sieg
Date of first publication:2023/05/19
Copyright:Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.
Funding:This research was funded by the Ministry of Culture and Science of the State of North Rhine-Westphalia, Germany, FKZ 005-2101-0144 and a start-up grant ‘Startförderung der H-BRS 2022’ by Bonn-Rhein-Sieg University of Applied Sciences. MA and MP are further supported by a grant from the German Research Foundation (DFG project no. 514177501)
Keyword:ENaC; automated electrophysiology; hypertension; sodium self-inhibition; two-electrode voltage clamp
Departments, institutes and facilities:Fachbereich Angewandte Naturwissenschaften
Institut für Technik, Ressourcenschonung und Energieeffizienz (TREE)
Institut für funktionale Gen-Analytik (IFGA)
Dewey Decimal Classification (DDC):5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie
Entry in this database:2023/05/23
Licence (German):License LogoCreative Commons - CC BY - Namensnennung 4.0 International