Molecular interactions in pulmonary surfactant films.

Pulmonary surfactant is a lipid-protein complex which has the essential physiological role of stabilizing the respiratory surface of lungs against collapse. To achieve this function, surfactant forms films at the air-liquid interface that reduce dramatically the surface tension of the thin aqueous layer lining the alveoli. Natural surfactant has optimised two important properties. Once secreted to the alveolar spaces, surfactant adsorbs rapidly to the interface. There, surfactant films reduce surface tension close to 0 mN/m when compressed during expiration. The design and production of efficient artificial surfactants for respiratory therapeutics is critically dependent on the knowledge of the molecular mechanisms governing efficient interfacial adsorption and optimal surface activity, in the context of respiratory cycling. The present review summarizes the data available today on the behaviour of the different molecular components of pulmonary surfactant at air-liquid interfaces. A working model is proposed of how surfactant films could modulate the respiratory dynamics. Copyright 2002 S. Karger AG, Basel