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Formation and structure of surface films: captive bubble surfactometry
S Schürch1, F H Green, H Bachofen
1Respiratory Research Group, Department of Physiology and Biophysics, University of Calgary, Health Sciences Centre, 3330 Hospital Drive N. W., Calgary, Alta. T2N 4N1, Canada. schurch@acs.ucalgary.ca
Biochimica Et Biophysica Acta
|November 14, 1998
Summary
Pulmonary surfactant adsorption follows a two-step process involving surface and subsurface layers. Multilaminated films form at higher concentrations, enhancing mechanical stability and compressibility for better lung function.
Area of Science:
- Biophysics
- Respiratory Physiology
Background:
- The extracellular alveolar lining layer traditionally comprises an aqueous subphase and a surfactant film.
- Recent studies confirm the existence of a continuous aqueous subphase and a polymorphous surfactant film in lungs.
Purpose of the Study:
- To investigate the dynamic adsorption behavior of pulmonary surfactant.
- To characterize the structure and properties of surfactant films formed in vitro and in vivo.
Main Methods:
- Modified adsorption model for pulmonary surfactant.
- Non-aqueous fixation technique using perfluorocarbon and osmium tetroxide for lung tissue.
- Transmission electron microscopy (TEM) of lung airspaces and in vitro surfactant films.
- Captive bubble system to study surfactant film formation.
Main Results:
- Pulmonary surfactant adsorption involves a two-step process: surface-subsurface transfer and subsurface-bulk solution exchange.
- TEM revealed a continuous osmiophilic film covering the alveolar surface, often appearing multilaminated.
- In vitro studies showed that higher surfactant concentrations (1 mg/ml) form thicker, multilaminated films with superior mechanical stability and compressibility compared to lower concentrations (0.3 mg/ml).
- Multilamellar vesicles and tubular myelin were observed associated with the surface film, but not essential for multilamellar film generation.
Conclusions:
- The dynamic adsorption of pulmonary surfactant is a complex process influenced by molecular transfer between layers.
- The in vivo and in vitro formation of multilaminated surfactant films is crucial for optimal lung function.
- Higher surfactant concentrations lead to more stable and compressible films, essential for maintaining alveolar integrity and reducing surface tension.