Hydrogen Peroxide Stimulates the Epithelial Sodium Channel through a Phosphatidylinositide 3-Kinase-dependent Pathway

• Type of Material: Article
• Authors: Heping Ma, Emory University
• Language: English
• Date: 2011-09-16
• Publisher: American Society for Biochemistry and Molecular Biology
• Publication Version: Final Published Version
• Copyright Statement: © 2011 by The American Society for Biochemistry and Molecular Biology, Inc.
• Final Published Version (URL): http://www.jbc.org/content/286/37/32444
• Title of Journal or Parent Work: Journal of Biological Chemistry
• ISSN: 0021-9258
• Volume: 286
• Issue: 37
• Start Page: 32444
• End Page: 32453
• Grant/Funding Information: This work was supported, in whole or in part, by National Institutes of Health Grant 5R01-DK067110 (to H.-P. M.).
• Keywords: Inositol Phospholipid; Patch Clamp Technique; Epithelial Cell; Sodium Channels; Reactive Oxygen Species (ROS); Phosphatidylinositol 3,4,5-Trisphosphate; Confocal Microscopy; Hydrogen Peroxide; ENaC; Intracellular Processing
• Research Categories: Biology, Physiology

Abstract

Recent studies indicate that oxidative stress mediates salt-sensitive hypertension. To test the hypothesis that the renal epithelial sodium channel (ENaC) is a target of oxidative stress, patch clamp techniques were used to determine whether ENaC in A6 distal nephron cells is regulated by hydrogen peroxide (H2O2). In the cell-attached configuration, H2O2 significantly increased ENaC open probability (Po) and single-channel current amplitude but not the unit conductance. High concentrations of exogenous H2O2 are required to elevate intracellular H2O2, probably because catalase, the enzyme that promotes the decomposition of H2O2 to H2O and O2, is highly expressed in A6 cells. The effect of H2O2 on ENaC Po was enhanced by 3-aminotriazole, a catalase inhibitor, and abolished by overexpression of catalase, indicating that intracellular H2O2 levels are critical to produce the effect. However, H2O2 did not directly activate ENaC in inside-out patches. The effects of H2O2 on ENaC Po and amiloride-sensitive Na+ current were abolished by inhibition of phosphatidylinositide 3-kinase (PI3K). Confocal microscopy data showed that H2O2 elevated phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3) in the apical membrane by stimulating PI3K. Because ENaC is stimulated by PI(3,4,5)P3, these data suggest that H2O2 stimulates ENaC via PI3K-mediated increases in apical PI(3,4,5)P3.