Expression of epithelial Na channels in Xenopus oocytes.

Details

Serval ID
serval:BIB_8AB6644763E5
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Expression of epithelial Na channels in Xenopus oocytes.
Journal
The Journal of general physiology
Author(s)
Palmer L.G., Corthesy-Theulaz I., Gaeggeler H.P., Kraehenbuhl J.P., Rossier B.
ISSN
0022-1295
ISSN-L
0022-1295
Publication state
Published
Issued date
07/1990
Peer-reviewed
Oui
Volume
96
Number
1
Pages
23-46
Language
english
Notes
Publication types: Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, P.H.S.
Publication Status: ppublish
Abstract
Epithelial Na channel activity was expressed in oocytes from Xenopus laevis after injection of mRNA from A6 cells, derived from Xenopus kidney. Poly A(+) RNA was extracted from confluent cell monolayers grown on either plastic or permeable supports. 1-50 ng RNA was injected into stage 5-6 oocytes. Na channel activity was assayed as amiloride-sensitive current (INa) under voltage-clamp conditions 1-3 d after injection. INa was not detectable in noninjected or water-injected oocytes. This amiloride-sensitive pathway induced by the mRNA had a number of characteristics in common with that in epithelial cells, including (a) high selectivity for Na over K, (b) high sensitivity to amiloride with an apparent K1 of approximately 100 nM, (c) saturation with respect to external Na with an apparent Km of approximately 10 mM, and (d) a time-dependent activation of current with hyperpolarization of the oocyte membrane. Expression of channel activity was temperature dependent, being slow at 19 degrees C but much more rapid at 25 degrees C. Fractionation of mRNA on a sucrose density gradient revealed that the species of RNA inducing channel activity had a sedimentation coefficient of approximately 17 S. Treatment of filter-grown cells with 300 nM aldosterone for 24 h increased Na transport in the A6 cells by up to fivefold but did not increase the ability of mRNA isolated from those cells to induce channel activity in oocytes. The apparent abundance of mRNA coding for channel activity was 10-fold less in cells grown on plastic than in those grown on filters, but was increased two- to threefold by aldosterone.
Keywords
Aldosterone/pharmacology, Amiloride/pharmacology, Animals, Electrophysiology, Epithelial Cells, Epithelium/metabolism, Gene Expression Regulation, Kinetics, Microelectrodes, Oocytes/metabolism, Potassium Chloride/pharmacology, RNA, Messenger/physiology, Sodium Channels/physiology, Temperature, Trypsin/pharmacology, Xenopus/physiology
Pubmed
Web of science
Open Access
Yes
Create date
24/01/2008 14:00
Last modification date
03/07/2024 6:59
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