Mechanisms of peroxynitrite-induced injury to pulmonary surfactants.
Activated alveolar macrophages secrete both nitric oxide and superoxide in the alveolar lining fluid which combine rapidly to form peroxynitrite, a potent oxidizing agent capable of damaging lipids and proteins in biological membranes. Peroxynitrite (1 mM) plus 100 microM Fe3+EDTA inhibited calf lung surfactant extract (CLSE) from reaching a minimum surface tension below 10 mN/m on dynamic compression. Peroxynitrite and its by-products reacted with the unsaturated lipid components of CLSE, as evidenced by the appearance of conjugated dienes and thiobarbituric acid products, and damaged all surfactant proteins. A mixture of the hydrophobic proteins [surfactant protein B (SP-B) and surfactant protein C (SP-C)] exposed to peroxynitrite became incapable of lowering phospholipid minimum surface tension on dynamic compression. Exposure of SP-A to peroxynitrite decreased its ability to cause lipid aggregation and to act synergistically with SP-B and SP-C in lowering surface tension of surfactant lipids. Western blot analysis of SP-A exposed to peroxynitrite was consistent with fragmentation and polymerization of the 28- to 36-kDa triplet band, and amino acid analysis revealed the presence of significant levels of 3-nitro-L-tyrosine. We conclude that peroxynitrite and its reactive intermediates inhibit pulmonary surfactant function by lipid peroxidation and damaging surfactant proteins.
Haddad
I Y
IY
Department of Anesthesiology, University of Alabama at Birmingham 35294.
Ischiropoulos
H
H
Holm
B A
BA
Beckman
J S
JS
Baker
J R
JR
Matalon
S
S
D000818:Animals; D015153:Blotting, Western; D001992:Bronchoalveolar Lavage Fluid; D002417:Cattle; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D015227:Lipid Peroxidation / Q000187:drug effects; D008970:Molecular Weight; D009566:Nitrates / Q000633:toxicity*; D011510:Proteolipids / Q000187:drug effects* / Q000302:isolation & purification / Q000378:metabolism; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000187:drug effects* / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D013499:Surface Properties; D013997:Time Factors
D006023:Glycoproteins; D009566:Nitrates; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; C039642:peroxynitric acid