Formation of lung surfactant films from intact lamellar bodies.

Publisher Website
Google Scholar
Abstract
Lamellar bodies, an intracellular source of lung alveolar surfactant, were isolated from rat lung homogenates and studied in the Langmuir-Adam surface balance. By layering intact lamellar bodies on the surface of a more dense sucrose subphase, the factors affecting film formation from surface tension-vs-time data and surface tension-surface area isotherms by compression and expansion of the resulting films were determined. Films with properties representative of the alveolar surfactant are apparently formed in the presence of Ca2+ or Mg2+ alone, or either plus Na+; film formation is incomplete with Na+ alone or on ion-free subphases; and Ca2+-induced film formation is blocked by chelation with EGTA but is unaffected by diisopropylfluorophosphate. Divalent cations can induce film formation by interactions at sites within the lamellar bodies and may be responsible for the binding of membrane lipids to membrane proteins in lung surfactant.