Ethanol stimulates epithelial sodium channels by elevating reactive oxygen species.
Alcohol affects total body sodium balance, but the molecular mechanism of its effect remains unclear. We used single-channel methods to examine how ethanol affects epithelial sodium channels (ENaC) in A6 distal nephron cells. The data showed that ethanol significantly increased both ENaC open probability (P(o)) and the number of active ENaC in patches (N). 1-Propanol and 1-butanol also increased ENaC activity, but iso-alcohols did not. The effects of ethanol were mimicked by acetaldehyde, the first metabolic product of ethanol, but not by acetone, the metabolic product of 2-propanol. Besides increasing open probability and apparent density of active channels, confocal microscopy and surface biotinylation showed that ethanol significantly increased α-ENaC protein in the apical membrane. The effects of ethanol on ENaC P(o) and N were abolished by a superoxide scavenger, 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy (TEMPOL) and blocked by the phosphatidylinositol 3-kinase inhibitor LY294002. Consistent with an effect of ethanol-induced reactive oxygen species (ROS) on ENaC, primary alcohols and acetaldehyde elevated intracellular ROS, but secondary alcohols did not. Taken together with our previous finding that ROS stimulate ENaC, the current results suggest that ethanol stimulates ENaC by elevating intracellular ROS probably via its metabolic product acetaldehyde.
Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA.
Hui-Fang
HF
Bao
John Z
JZ
Song
Billie J
BJ
Duke
He-Ping
HP
Ma
Donald D
DD
Denson
Douglas C
DC
Eaton
D000079:Acetaldehyde / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D002867:Chromones / Q000494:pharmacology; D003497:Cyclic N-Oxides / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D062708:Epithelial Sodium Channel Agonists / Q000494:pharmacology*; D053503:Epithelial Sodium Channels / Q000187:drug effects* / Q000378:metabolism; D000431:Ethanol / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000494:pharmacology; D009025:Morpholines / Q000494:pharmacology; D009399:Nephrons / Q000187:drug effects / Q000378:metabolism; D018408:Patch-Clamp Techniques; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013113:Spin Labels; D014982:Xenopus laevis
D002867:Chromones; D003497:Cyclic N-Oxides; D004791:Enzyme Inhibitors; D062708:Epithelial Sodium Channel Agonists; D053503:Epithelial Sodium Channels; D016166:Free Radical Scavengers; D009025:Morpholines; D017382:Reactive Oxygen Species; D013113:Spin Labels; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D000431:Ethanol; D000079:Acetaldehyde; C001803:tempol