Nitric oxide inhibits highly selective sodium channels and the Na+/K+-ATPase in H441 cells.
Nitric oxide (NO) is an important regulator of Na(+) reabsorption by pulmonary epithelial cells and therefore of alveolar fluid clearance. The mechanisms by which NO affects epithelial ion transport are poorly understood and vary from model to model. In this study, the effects of NO on sodium reabsorption by H441 cell monolayers were studied in an Ussing chamber. Two NO donors, (Z)-1-[N-(3-aminopropyl)-N-(n-propyl)amino]diazen-1-ium-1,2-diolate and diethylammonium (Z)-1-(N,N-diethylamino)diazen-1-ium-1,2-diolate, rapidly, reversibly, and dose-dependently reduced amiloride-sensitive, short-circuit currents across H441 cell monolayers. This effect was neutralized by the NO scavenger hemoglobin and was not observed with inactive NO donors. The effects of NO were not blocked by 8-bromoguanosine-3',5'-cyclic monophosphate or by soluble guanylate cyclase inhibitors (methylene blue and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) and were therefore independent of soluble guanylate cyclase signaling. NO targeted apical, highly selective, amiloride-sensitive Na(+) channels in basolaterally permeabilized H441 cell monolayers. NO had no effect on the activity of the human epithelial sodium channel heterologously expressed in Xenopus oocytes. NO decreased Na(+)/K(+)-ATPase activity in apically permeabilized H441 cell monolayers. The inhibition of Na(+)/K(+)-ATPase activity by NO was reversed by mercury and was mimicked by N-ethylmaleimide, which are agents that reverse and mimic, respectively, the reaction of NO with thiol groups. Consistent with these data, S-NO groups were detected on the Na(+)/K(+)-ATPase α subunit in response to NO-donor application, using a biotin-switch approach coupled to a Western blot. These data demonstrate that, in the H441 cell model, NO impairs Na(+) reabsorption by interfering with the activity of highly selective Na(+) channels and the Na(+)/K(+)-ATPase.
Althaus
Mike
M
Department of Internal Medicine (Pulmonology), University of Giessen Lung Center, Justus Liebig University, Giessen, Germany.
Pichl
Alexandra
A
Clauss
Wolfgang G
WG
Seeger
Werner
W
Fronius
Martin
M
Morty
Rory E
RE
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D019921:Biotinylation; D015153:Blotting, Western; D055745:Bronchioles / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D002460:Cell Line; D006152:Cyclic GMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects* / Q000201:enzymology; D053503:Epithelial Sodium Channels / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D006162:Guanylate Cyclase / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D006834:Hydrazines / Q000494:pharmacology*; D008564:Membrane Potentials; D009569:Nitric Oxide / Q000378:metabolism* / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D026941:Sodium Channel Blockers / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000071756:Soluble Guanylyl Cyclase; D013438:Sulfhydryl Compounds / Q000378:metabolism; D014981:Xenopus
D004791:Enzyme Inhibitors; D053503:Epithelial Sodium Channels; D006454:Hemoglobins; D006834:Hydrazines; D020030:Nitric Oxide Donors; C112653:PAPA NONOate; D018160:Receptors, Cytoplasmic and Nuclear; C507045:SCNN1A protein, human; C507048:SCNN1B protein, human; C507052:SCNN1G protein, human; D026941:Sodium Channel Blockers; D013438:Sulfhydryl Compounds; D009569:Nitric Oxide; D000584:Amiloride; C084012:1,1-diethyl-2-hydroxy-2-nitrosohydrazine; D012964:Sodium; C499076:ATP1A1 protein, human; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase; D000254:Sodium-Potassium-Exchanging ATPase; D006152:Cyclic GMP