Characterization of constitutive and acid-induced outwardly rectifying chloride currents in immortalized mouse distal tubular cells

Valinsky, W. C., Touyz, R. M. and Shrier, A. (2017) Characterization of constitutive and acid-induced outwardly rectifying chloride currents in immortalized mouse distal tubular cells. Biochimica et Biophysica Acta: General Subjects, 1861(8), pp. 2007-2019. (doi: 10.1016/j.bbagen.2017.05.004) (PMID:28483640) (PMCID:PMC5482324)

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Abstract

Thiazides block Na+ reabsorption while enhancing Ca2 + reabsorption in the kidney. As previously demonstrated in immortalized mouse DCT (MDCT) cells, chlorothiazide application induced a robust plasma membrane hyperpolarization, which increased Ca2 + uptake. This essential thiazide-induced hyperpolarization was prevented by the Cl− channel inhibitor 5-Nitro-2-(3-phenylpropylamino) benzoic acid (NPPB), implicating NPPB-sensitive Cl− channels, however the nature of these Cl− channels has been rarely described in the literature. Here we show that MDCT cells express a dominant, outwardly rectifying Cl− current at extracellular pH 7.4. This constitutive Cl− current was more permeable to larger anions (Eisenman sequence I; I− > Br− ≥ Cl−) and was substantially inhibited by > 100 mM [Ca2 +]o, which distinguished it from ClC-K2/Barttin. Moreover, the constitutive Cl− current was blocked by NPPB, along with other Cl− channel inhibitors (DIDS, FFA). Subjecting the MDCT cells to an acidic extracellular solution (pH < 5.5) induced a substantially larger outwardly rectifying NPPB-sensitive Cl− current. This acid-induced Cl− current was also anion permeable (I− > Br− > Cl−), but was distinguished from the constitutive Cl− current by its rectification characteristics, ion sensitivities, and response to FFA. In addition, we have identified similar outwardly rectifying and acid-sensitive currents in immortalized cells from the inner medullary collecting duct (mIMCD-3 cells). Expression of an acid-induced Cl− current would be particularly relevant in the acidic IMCD (pH < 5.5). To our knowledge, the properties of these Cl− currents are unique and provide the mechanisms to account for the Cl− efflux previously speculated to be present in MDCT cells.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Touyz, Professor Rhian
Authors: Valinsky, W. C., Touyz, R. M., and Shrier, A.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cardiovascular and Medical Sciences
Journal Name:Biochimica et Biophysica Acta: General Subjects
Publisher:Elsevier
ISSN:0304-4165
ISSN (Online):1872-8006
Published Online:05 May 2017
Copyright Holders:Copyright © 2017 The Authors
First Published:First published in Biochimica et Biophysica Acta: General Subjects 1861(8):2007-2019
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
607381Vascular Noxs as therapeutic targets and biomarkers in hypertensionRhian TouyzBritish Heart Foundation (BHF)CH/12/4/29762RI CARDIOVASCULAR & MEDICAL SCIENCES