EFFECTS OF SMOKE-INHALATION ON ALVEOLAR SURFACTANT SUBTYPES IN MICE

The effects of smoke inhalation on alveolar surfactant subtypes were e xamined in mice exposed for 30 minutes to smoke generated from the bur ning of a flexible polyurethane foam. At 4 or 12 hours after the expos ure, three surfactant pellets, P10, P60, and P100, and a supernatant, S100, were prepared by sequential centrifugation of lavage fluids at 1 0,000 g for 30 minutes (P10), 60,000 g for 60 minutes (P60), and 100,0 00 g for 15 hours (P100 and S100). Phospholipid analysis and electron microscopy were performed on each fraction Smoke exposure dramatically altered the normal distributions of these fractions: it significantly increased the phospholipid content of the heavier subtype, P10, which is thought to represent newly secreted surfactant; had no effect on t he intermediate form, P60; and dramatically increased the phospholipid contest (approximately fivefold) of the lighter subtypes, P100 and S1 00, which are believed to represent catabolic end-products of alveolar surfactant. only P100 was structurally altered by the smoke. These re sults represent alterations of the normal metabolic processing of alve olar surfactant. Whereas the mechanism is yet to be defined it seems t o involve a small but significant increase in the newly secreted surfa ctant, as well as an excessively high accumulation of the structurally altered catabolic forms of the secreted surfactant.