title: Atomic force microscopy analysis of rat pulmonary surfactant films.
abstract: Pulmonary surfactant facilitates breathing by forming a surface tension reducing film at the air-liquid interface of the alveoli. The objective was to characterize the structure of surfactant films using endogenous rat surfactant. Solid-support surfactant films, at different surface pressures, were obtained using a Langmuir balance and were analyzed using atomic force microscopy. The results showed a lipid film structure with three distinct phases: liquid expanded, liquid ordered and liquid condensed. The area covered by the liquid condensed domains increased as surface pressure increased. The presence of liquid ordered phase within these structures correlated with the cholesterol content. At a surface pressure of 50 mN/m, stacks of bilayers appeared. Several structural details of these films differ from previous observations made with goat and exogenous surfactants. Overall, the data indicate that surfactant films demonstrate phase separation at low surface pressures and multilayer formation at higher pressure, features likely important for normal surfactant function.
authors.affiliation: Lawson Health Research Institute, University of Western Ontario, London, Canada.
authors.forename: Xiujun
authors.initials: X
authors.lastname: Jiao
authors.forename: Eleonora
authors.initials: E
authors.lastname: Keating
authors.forename: Seyed
authors.initials: S
authors.lastname: Tadayyon
authors.forename: Fred
authors.initials: F
authors.lastname: Possmayer
authors.forename: Yi Y
authors.initials: YY
authors.lastname: Zuo
authors.forename: Ruud A W
authors.initials: RA
authors.lastname: Veldhuizen
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000032:analysis / Q000302:isolation & purification; D008168:Lung / Q000737:chemistry*; D008297:Male; D018625:Microscopy, Atomic Force; D010743:Phospholipids / Q000032:analysis* / Q000302:isolation & purification; D011663:Pulmonary Surfactants / Q000737:chemistry* / Q000302:isolation & purification; D051381:Rats; D017207:Rats, Sprague-Dawley; D021241:Spectrometry, Mass, Electrospray Ionization; D013499:Surface Properties
chemical_list: D010743:Phospholipids; D011663:Pulmonary Surfactants; D002784:Cholesterol