title: Physiological variables affecting surface film formation by native lamellar body-like pulmonary surfactant particles.
abstract: Pulmonary surfactant (PS) is a surface active complex of lipids and proteins that prevents the alveolar structures from collapsing and reduces the work of breathing by lowering the surface tension at the alveolar air-liquid interface (ALI). Surfactant is synthesized by the alveolar type II (AT II) cells, and it is stored in specialized organelles, the lamellar bodies (LBs), as tightly packed lipid bilayers. Upon secretion into the alveolar lining fluid, a large fraction of these particles retain most of their packed lamellar structure, giving rise to the term lamellar body like-particles (LBPs). Due to their stability in aqueous media, freshly secreted LBPs can be harvested from AT II cell preparations. However, when LBPs get in contact with an ALI, they quickly and spontaneously adsorb into a highly organized surface film. In the present study we investigated the adsorptive capacity of LBPs at an ALI under relevant physiological parameters that characterize the alveolar environment in homeostatic or in pathological conditions. Adsorption of LBPs at an ALI is highly sensitive to pH, temperature and albumin concentration and to a relatively lesser extent to changes in osmolarity or Ca(2+) concentrations in the physiological range. Furthermore, proteolysis of LBPs significantly decreases their adsorptive capacity confirming the important role of surfactant proteins in the formation of surface active films.
authors.affiliation: Department of Physiology and Medical Physics, Division of Physiology, Innsbruck Medical University, 6020 Innsbruck, Austria; Institute of General Physiology, University of Ulm, 89081 Ulm, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Hobi
authors.affiliation: Department of Physiology and Medical Physics, Division of Physiology, Innsbruck Medical University, 6020 Innsbruck, Austria.
authors.forename: Gerlinde
authors.initials: G
authors.lastname: Siber
authors.affiliation: Department of Physiology and Medical Physics, Division of Physiology, Medical University Innsbruck, Fritz-Preglstr. 3 6020 Innsbruck, Austria.
authors.forename: Virginia
authors.initials: V
authors.lastname: Bouzas
authors.affiliation: Department of Physiology and Medical Physics, Division of Physiology, Innsbruck Medical University, 6020 Innsbruck, Austria.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ravasio
authors.affiliation: Department of Physiology and Medical Physics, Division of Physiology, Medical University Innsbruck, Fritz-Preglstr. 3 6020 Innsbruck, Austria.
authors.forename: Jesus
authors.initials: J
authors.lastname: Pérez-Gil
authors.affiliation: Department of Physiology and Medical Physics, Division of Physiology, Innsbruck Medical University, 6020 Innsbruck, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Haller
mesh_terms: D000327:Adsorption; D000818:Animals; D002118:Calcium / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008051:Lipid Bilayers / Q000378:metabolism; D009997:Osmotic Pressure; D011506:Proteins / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000378:metabolism*; D011663:Pulmonary Surfactants / Q000378:metabolism*; D051381:Rats
chemical_list: D008051:Lipid Bilayers; D011506:Proteins; D011663:Pulmonary Surfactants; D002118:Calcium
keywords: Adsorption at the air–liquid interface; Lamellar body-like surfactant particles; Lung diseases; Phospholipids; Physiological milieu in alveolar lining fluid; Surfactant therapies