title: Regulation of alveolar epithelial Na+ channels by ERK1/2 in chlorine-breathing mice.
abstract: The mechanisms by which the exposure of mice to Cl(2) decreases vectorial Na(+) transport and fluid clearance across their distal lung spaces have not been elucidated. We examined the biophysical, biochemical, and physiological changes of rodent lung epithelial Na(+) channels (ENaCs) after exposure to Cl(2), and identified the mechanisms involved. We measured amiloride-sensitive short-circuit currents (I(amil)) across isolated alveolar Type II (ATII) cell monolayers and ENaC single-channel properties by patching ATII and ATI cells in situ. α-ENaC, γ-ENaC, total and phosphorylated extracellular signal-related kinase (ERK)1/2, and advanced products of lipid peroxidation in ATII cells were measured by Western blot analysis. Concentrations of reactive intermediates were assessed by electron spin resonance (ESR). Amiloride-sensitive Na(+) channels with conductances of 4.5 and 18 pS were evident in ATI and ATII cells in situ of air-breathing mice. At 1 hour and 24 hours after exposure to Cl(2), the open probabilities of these two channels decreased. This effect was prevented by incubating lung slices with inhibitors of ERK1/2 or of proteasomes and lysosomes. The exposure of ATII cell monolayers to Cl(2) increased concentrations of reactive intermediates, leading to ERK1/2 phosphorylation and decreased I(amil) and α-ENaC concentrations at 1 hour and 24 hours after exposure. The administration of antioxidants to ATII cells before and after exposure to Cl(2) decreased concentrations of reactive intermediates and ERK1/2 activation, which mitigated the decrease in I(amil) and ENaC concentrations. The reactive intermediates formed during and after exposure to Cl(2) activated ERK1/2 in ATII cells in vitro and in vivo, leading to decreased ENaC concentrations and activity.
authors: Department of Anesthesiology, School of Medicine, University of Alabama at Birmingham, BMR II 224, 901 19th St. South, Birmingham, AL 35205-3703, USA.
authors: Ahmed
authors: A
authors: Lazrak
authors: Lan
authors: L
authors: Chen
authors: Asta
authors: A
authors: Jurkuvenaite
authors: Stephen F
authors: SF
authors: Doran
authors: Gang
authors: G
authors: Liu
authors: Qian
authors: Q
authors: Li
authors: Jack R
authors: JR
authors: Lancaster
authors: Sadis
authors: S
authors: Matalon
mesh_terms: D000280:Administration, Inhalation; D056809:Alveolar Epithelial Cells / Q000187:drug effects* / Q000201:enzymology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D015153:Blotting, Western; D002478:Cells, Cultured; D002713:Chlorine / Q000008:administration & dosage*; D017097:Electric Impedance; D004789:Enzyme Activation; D053503:Epithelial Sodium Channels / Q000187:drug effects* / Q000378:metabolism; D007150:Immunohistochemistry; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008564:Membrane Potentials; D051379:Mice; D008810:Mice, Inbred C57BL; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011650:Pulmonary Alveoli / Q000187:drug effects* / Q000201:enzymology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors
chemical_list: D000975:Antioxidants; D053503:Epithelial Sodium Channels; D047428:Protein Kinase Inhibitors; D017382:Reactive Oxygen Species; C507047:Scnn1a protein, mouse; C440894:Scnn1a protein, rat; C507053:Scnn1g protein, mouse; C507054:Scnn1g protein, rat; D002713:Chlorine; C535148:Mapk1 protein, mouse; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3