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Contribution of Endogenous Hydrogen Sulfide to Hypoxic Inhibition of Sodium Transport by Lung Epithelial Cells
Author(s) -
Althaus Mike,
Krause Nicole Catherine,
Pott Jennifer,
Münch Lena Katharina,
Olson Kenneth R
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.746.6
Subject(s) - chemistry , cystathionine beta synthase , amiloride , sodium , sodium hydrosulfide , biochemistry , sodium nitrite , sodium channel , biophysics , hypoxia (environmental) , hydrogen sulfide , epithelial sodium channel , oxygen , enzyme , biology , sulfur , organic chemistry , cysteine
In lung epithelial cells, hypoxia decreases the expression and activity of sodium transporting molecules, thereby reducing the rate of transepithelial sodium absorption. The mechanisms underlying the sensing of hypoxia and subsequent coupling to sodium transporting molecules remain unclear. Hydrogen sulfide (H 2 S) has recently been recognized as a cellular signaling molecule whose intracellular concentrations critically depend on oxygen levels. Therefore it was questioned whether endogenously produced H 2 S contributes to hypoxic inhibition of sodium transport. H 2 S is generated by multiple pathways involving cystathionine‐γ‐lyase (CSE), cystathionine‐β‐synthase (CBS) and 3‐mercaptopyruvate sulfurtransferase (3‐MST). RT‐PCR and immunoblotting experiments revealed the presence of all of these enzymes in human H441 lung epithelial cells. Using an amperometric H 2 S‐sensitive electrode, H 2 S‐production by H441 lysates was detected. H 2 S‐production inversely correlated with oxygen concentrations. In electrophysiological Ussing chamber experiments, exogenous application of H 2 S by the sulfur salt Na 2 S inhibited amiloride‐sensitive sodium transport by cultured H441 monolayers. Furthermore, acute hypoxia which was established by decreasing oxygen concentrations from 10 % to 0.1 % for 30 min decreased amiloride‐sensitive sodium transport by these cells. Pretreatment with the CSE‐inhibitor D/L‐propargylglycine (PAG) decreased hypoxic inhibition of sodium transport, whereas inhibition of CBS (with aminooxy‐acetic acid; AOAA) or 3‐MST (with aspartate) had no effect. Inhibition of all H 2 S‐generating enzymes with a combination of AOAA, PAG and aspartate abrogated the hypoxic inhibition of sodium transport. By contrast, increasing the concentrations of L‐cysteine, pyridoxalphosphate and α‐ketoglutarate, precursors of H 2 S production, did not enhance the effect of hypoxia. These data indicate that H441 lung epithelial cells endogenously produce H 2 S during hypoxia and this might contribute to hypoxic inhibition of sodium absorption. Support or Funding Information This work was funded by the German Research Foundation (AL‐1453/1‐2).