Journal Mobile Options
Table of Contents
Vol. 23, No. 1-3, 2009
Issue release date: 2009
Section title: Original Paper
Cell Physiol Biochem 2009;23:009–024
(DOI:10.1159/000204076)

Expression of ENaC and other Transport Proteins in Xenopus Oocytes is Modulated by Intracellular Na+

Kusche-Vihrog K.1,* · Segal A.2,* · Grygorczyk R.3 · Bangel-Ruland N.1 · Van Driessche W.2 · Weber W.-M.1
1 Institute of Animal Physiology, Westphalian Wilhelms-University Muenster,2Laboratory of Physiology, KU Leuven, Campus Gasthuisberg, Leuven,3Research Centre, Centre hospitalier de l’Université de Montréal - Hôtel-Dieu, 3850 Saint-Urbain, Montréal,*These authors contributed equally
email Corresponding Author

Wolf-Michael Weber

Institute of Animal Physiology, WWU Muenster

Hindenburgplatz 55, 48143 Muenster (Germany)

Tel. +49 251 83 21782, Fax: +49 251 83 21785

E-Mail wmw@uni-muenster.de

Do you have an account?

Register and profit from personalized services (MyKarger) Login Information

Please create your User ID & Password





Contact Information









I have read the Karger Terms and Conditions and agree.

Abstract

The expression of the epithelial Na+ channel (ENaC) is tissue-specific and dependent on a variety of mediators and interacting proteins. Here we examined the role of intracellular Na+ ([Na+]i) as a modulator of the expression of rat ENaC in Xenopus laevis oocytes. We manipulated [Na+]i of ENaC-expressing oocytes in the range of 0-20 mM by incubating in extracellular solutions of different [Na+]o. Electrophysiological, protein biochemical and fluorescence optical methods were used to determine the effects of different [Na+]i on ENaC expression and membrane abundance. In voltage-clamp experiments we found that amiloride-sensitive ENaC current (Iami) and conductance (Gami) peak at a [Na+]i of ∼10 mM Na+, but were significantly reduced in 5 mM and 20 mM [Na+]i. Fluorescence intensity of EGFP-ENaC-expressing oocytes also followed a bell-shaped curve with a maximum at ∼ 10 mM [Na+]i. In Western blot experiments with specific anti-ENaC antibodies the highest protein expression was found in ENaC-expressing oocytes with [Na+]i of 10-15 mM. Since ENaC is also highly permeable for Li+, we incubated ENaC-expressing oocytes in different Li+ concentrations and found a peak of Iami and Gami with 5 mM Li+. The influence of [Na+]i on the expression is not ENaC-specific, since expression of a Cl- channel (CFTR) and a Na+/glucose cotransporter (SGLT1) showed the same dependence on [Na+]i. We conclude that specific concentrations of Na+ and Li+ influence the expression and abundance of ENaC and other transport proteins in the plasma membrane in Xenopus laevis oocytes. Furthermore, we suggest the existence of a general mechanism dependent on monovalent cations that optimizes the expression of membrane proteins.

© 2009 S. Karger AG, Basel


Article / Publication Details

First-Page Preview
Abstract of Original Paper

Accepted: 11/7/2008
Published online: 2/18/2009
Issue release date: 2009

Number of Print Pages: 16
Number of Figures: 0
Number of Tables: 0

ISSN: 1015-8987 (Print)
eISSN: 1421-9778 (Online)

For additional information: http://www.karger.com/CPB


Copyright / Drug Dosage / Disclaimer

Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher or, in the case of photocopying, direct payment of a specified fee to the Copyright Clearance Center.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.