10781434

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We assessed whether reactive oxygen-nitrogen intermediates generated by alveolar macrophages (AMs) oxidized and nitrated human surfactant protein (SP) A. SP-A was exposed to lipopolysaccharide (100 ng/ml)-activated AMs in 15 mM HEPES (pH 7.4) for 30 min in the presence and absence of 1.2 mM CO(2). In the presence of CO(2), lipopolysaccharide-stimulated AMs had significantly higher nitric oxide synthase (NOS) activity (as quantified by the conversion of L-[U-(14)C]arginine to L-[U-(14)C]citrulline) and secreted threefold higher levels of nitrate plus nitrite in the medium [28 +/- 3 vs. 6 +/- 1 (SE) nmol. 6.5 h(-1). 10(6) AMs(-1)]. Western blotting studies of immunoprecipitated SP-A indicated that CO(2) enhanced SP-A nitration by AMs and decreased carbonyl formation. CO(2) (0-1.2 mM) also augmented peroxynitrite (0.5 mM)-induced SP-A nitration in a dose-dependent fashion. Peroxynitrite decreased the ability of SP-A to aggregate lipids, and this inhibition was augmented by 1.2 mM CO(2). Mass spectrometry analysis of chymotryptic fragments of peroxynitrite-exposed SP-A showed nitration of two tyrosines (Tyr(164) and Tyr(166)) in the absence of CO(2) and three tyrosines (Tyr(164), Tyr(166), and Tyr(161)) in the presence of 1.2 mM CO(2). These findings indicate that physiological levels of peroxynitrite, produced by activated AMs, nitrate SP-A and that CO(2) increased nitration, at least partially, by enhancing enzymatic nitric oxide production.

eng

IM

MEDLINE

1040-0605

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NLM

L1025-31

pubmed-meshheading:10781434-Carbon Dioxide, pubmed-meshheading:10781434-Cells, Cultured, pubmed-meshheading:10781434-Enzyme Activation, pubmed-meshheading:10781434-Epithelial Cells, pubmed-meshheading:10781434-Humans, pubmed-meshheading:10781434-Hypercapnia, pubmed-meshheading:10781434-Lipid Metabolism, pubmed-meshheading:10781434-Lipopolysaccharides, pubmed-meshheading:10781434-Macrophages, Alveolar, pubmed-meshheading:10781434-Mass Spectrometry, pubmed-meshheading:10781434-Molsidomine, pubmed-meshheading:10781434-Nitrates, pubmed-meshheading:10781434-Nitric Oxide, pubmed-meshheading:10781434-Nitric Oxide Donors, pubmed-meshheading:10781434-Nitric Oxide Synthase, pubmed-meshheading:10781434-Nitrites, pubmed-meshheading:10781434-Oxidation-Reduction, pubmed-meshheading:10781434-Proteolipids, pubmed-meshheading:10781434-Pulmonary Surfactant-Associated Protein A, pubmed-meshheading:10781434-Pulmonary Surfactant-Associated Proteins, pubmed-meshheading:10781434-Pulmonary Surfactants, pubmed-meshheading:10781434-Respiratory Distress Syndrome, Adult, pubmed-meshheading:10781434-Tyrosine

Carbon dioxide enhances nitration of surfactant protein A by activated alveolar macrophages.

Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't