S-Nitrosothiols signal hypoxia-mimetic vascular pathology
Lisa A. Palmer, … , Timothy Macdonald, Benjamin Gaston
Lisa A. Palmer, … , Timothy Macdonald, Benjamin Gaston
Published September 4, 2007
Citation Information: J Clin Invest. 2007;117(9):2592-2601. https://doi.org/10.1172/JCI29444.
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Research Article

S-Nitrosothiols signal hypoxia-mimetic vascular pathology

Abstract

NO transfer reactions between protein and peptide cysteines have been proposed to represent regulated signaling processes. We used the pharmaceutical antioxidant N-acetylcysteine (NAC) as a bait reactant to measure NO transfer reactions in blood and to study the vascular effects of these reactions in vivo. NAC was converted to S-nitroso-N-acetylcysteine (SNOAC), decreasing erythrocytic S-nitrosothiol content, both during whole-blood deoxygenation ex vivo and during a 3-week protocol in which mice received high-dose NAC in vivo. Strikingly, the NAC-treated mice developed pulmonary arterial hypertension (PAH) that mimicked the effects of chronic hypoxia. Moreover, systemic SNOAC administration recapitulated effects of both NAC and hypoxia. eNOS-deficient mice were protected from the effects of NAC but not SNOAC, suggesting that conversion of NAC to SNOAC was necessary for the development of PAH. These data reveal an unanticipated adverse effect of chronic NAC administration and introduce a new animal model of PAH. Moreover, evidence that conversion of NAC to SNOAC during blood deoxygenation is necessary for the development of PAH in this model challenges conventional views of oxygen sensing and of NO signaling.

Authors

Lisa A. Palmer, Allan Doctor, Preeti Chhabra, Mary Lynn Sheram, Victor E. Laubach, Molly Z. Karlinsey, Michael S. Forbes, Timothy Macdonald, Benjamin Gaston

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Figure 4

SNOAC recapitulates in primary pulmonary arterial endothelial cells the hypoxia-mimetic whole-lung effect of chronic NAC administration on Sp3 expression in vivo.

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SNOAC recapitulates in primary pulmonary arterial endothelial cells the ...
(A) One micromolar SNOAC, but not 50 μM NAC, treatment (4 hours each) increased intracellular S-nitrosothiol levels (assayed by Cu/cysteine chemiluminescence; ref. 11) in primary murine pulmonary endothelial cells (*P < 0.05 compared with SNOAC treatment). (B) Immunoblot showing increased Sp3 expression relative to MAPK in the whole-lung homogenates of mice treated for 3 weeks with 10 mg/ml NAC but not in those of control mice. By densitometry, this increase was significant (P < 0.01). (C) Paradoxically, however, NAC (50 μM; 4 hours) did not increase Sp3 expression relative to β-actin in primary murine pulmonary endothelial cells in vitro, while both SNOAC (1 μM; 4 hours) and hypoxia (10%; 4 hours) did.