Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/47313
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Type: Journal article
Title: Tetraethylammonium block of water flux in Aquaporin-1 channels expressed in kidney thin limbs of Henle's loop and a kidney-derived cell line
Author: Yool, A.
Brokl, O.
Pannabecker, T.
Dantzler, W.
Stamer, W.
Citation: BMC Physiology, 2002; 2(1):1-8
Publisher: BioMed Central Ltd.
Issue Date: 2002
ISSN: 1472-6793
1472-6793
Statement of
Responsibility: 
Andrea J Yool, Olga H Brokl, Thomas L Pannabecker, William H Dantzler and W Daniel Stamer
Abstract: BACKGROUND: Aquaporin-1 (AQP1) channels are constitutively active water channels that allow rapid transmembrane osmotic water flux, and also serve as cyclic-GMP-gated ion channels. Tetraethylammonium chloride (TEA; 0.05 to 10 mM) was shown previously to inhibit the osmotic water permeability of human AQP1 channels expressed in Xenopus oocytes. The purpose of the present study was to determine if TEA blocks osmotic water flux of native AQP1 channels in kidney, and recombinant AQP1 channels expressed in a kidney derived MDCK cell line. We also demonstrate that TEA does not inhibit the cGMP-dependent ionic conductance of AQP1 expressed in oocytes, supporting the idea that water and ion fluxes involve pharmacologically distinct pathways in the AQP1 tetrameric complex. RESULTS: TEA blocked water permeability of AQP1 channels in kidney and kidney-derived cells, demonstrating this effect is not limited to the oocyte expression system. Equivalent inhibition is seen in MDCK cells with viral-mediated AQP1 expression, and in rat renal descending thin limbs of Henle's loops which abundantly express native AQP1, but not in ascending thin limbs which do not express AQP1. External TEA (10 mM) does not block the cGMP-dependent AQP1 ionic conductance, measured by two-electrode voltage clamp after pre-incubation of oocytes in 8Br-cGMP (10–50 mM) or during application of the nitric oxide donor, sodium nitroprusside (2–4 mM). CONCLUSIONS: TEA selectively inhibits osmotic water permeability through native and heterologously expressed AQP1 channels. The pathways for water and ions in AQP1 differ in pharmacological sensitivity to TEA, and are consistent with the idea of independent solute pathways within the channel structure. The results confirm the usefulness of TEA as a pharmacological tool for the analysis of AQP1 function.
Keywords: Oocytes; Kidney; Loop of Henle; Cells, Cultured; Cell Line; Animals; Xenopus; Dogs; Rats; Rats, Wistar; Water; Tetraethylammonium; Aquaporins; Culture Techniques; Patch-Clamp Techniques; Cell Membrane Permeability; Electric Conductivity; Male; Aquaporin 1
Description: © 2002 Yool et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
RMID: 0020081574
DOI: 10.1186/1472-6793-2-4
Published version: http://www.biomedcentral.com/1472-6793/2/4
Appears in Collections:Molecular and Biomedical Science publications

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