SYNTHETIC SURFACTANT SCAVENGES OXIDANTS AND PROTECTS AGAINST HYPEROXIC LUNG INJURY

Injury and mortality after exposure to 100% oxygen can be diminished b y surfactants that may operate by mechanisms other than those responsi ble for surface tension effects. We tested the hypotheses that 1) synt hetic surfactant and its components function as antioxidants in vitro and 2) decrements in hyperoxic injury after treatment with a surfactan t and its components are associated with decreases in oxidative stress to the lung. A synthetic surfactant (Exosurf) and its non-surface-act ive components tyloxapol and cetyl alcohol were incubated in an iron-c ontaining hydroxyl radical-generating system to determine their abilit ies to prevent oxidation of deoxyribose. Doses of tyloxapol, cetyl alc ohol, and artificial surfactant diminished the absorbance of thiobarbi turic acid-reactive products of deoxyribose. Similarly, tyloxapol, cet yl alcohol, and the surfactant decreased hydroxylated products of sali cylate in the same system. Rats were instilled intratracheally with sa line, tyloxapol, tyloxapol plus cetyl alcohol, or artificial surfactan t and immediately exposed to air or 100% oxygen. After 61 h of oxygen exposure, pleural fluid volume and wet-to-dry lung weight ratios were decreased in animals treated with surfactant and/or its components. Th ere were also decrements in thiobarbituric acid-reactive products of l ung tissue. In separate experiments, mean survival of saline-treated r ats exposed to 100% oxygen was 67.3 +/- 8.1 h and >96 h for rats given the surfactant or its components. We conclude that tyloxapol, cetyl a lcohol, and Exosurf can function as antioxidants in vitro and their in vivo instillation is associated with reduction in measures of hyperox ic injury, oxidized tissue products, and mortality.