TY  - JOUR
U1  - Zeitschriftenartikel, wissenschaftlich - begutachtet (reviewed)
A1  - Althaus, Mike
A1  - Pichl, Alexandra
A1  - Clauss, Wolfgang G.
A1  - Seeger, Werner
A1  - Fronius, Martin
A1  - Morty, Rory E.
T1  - Nitric Oxide Inhibits Highly Selective Sodium Channels and the Na+/K+-ATPase in H441 Cells
JF  - American Journal of Respiratory Cell and Molecular Biology
N2  - 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 a 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.
KW  - alveolar epithelium
KW  - nitric oxide
KW  - Na+/K+-ATPase
KW  - sodium transport
KW  - ENaC
SN  - 1044-1549
SS  - 1044-1549
U6  - https://doi.org/10.1165/2009-0335OC
DO  - https://doi.org/10.1165/2009-0335OC
PM  - 20139350
VL  - 44
IS  - 1
SP  - 53
EP  - 65
S1  - 13
PB  - American Thoracic Society
ER  -