SEGMENTAL REVERSIBILITY AND HYSTERESIS OF PREPARATIONS SIMILAR TO LUNG SURFACTANT.
Technical rept., Apr 66-Feb 67,
EDGEWOOD ARSENAL MD
Pagination or Media Count:
The object of this study was to investigate the segmental reversibility of the compression isotherms of various surfactant preparations in an effort to gain some insight into the nature of the hysteresis phenomenon. Three classes of surfactant were employed a surface-active rabbit lung lipoprotein and two groups of pure lipids similar to those found in a lung surfactant. One group of lipids consisted solely of saturated compounds and the other, of unsaturated compounds. It was concluded that each type of surfactant produced a distinctly different response to segmental reexpansion of compression isotherms of equilibrium-point EP films. The unsaturated lipids exhibited little hypercompressibility on lateral compression and little to no hysteresis on reexpansion. The saturated lipids exhibited marked hypercompressibility on lateral compression, and the response to segmental reexpansion was dual. Reexpansion on compression between the EP and the isotension point IP produced no hysteresis, whereas compression beyond the IP produced increasing amounts of hysteresis. With the lipoprotein films, hysteresis was not related to hypercompressibility and IP but to the lateral pressure exerted on the film. When this compression pressure exceeds 10 to 15 dynes, hysteresis occurs. Author
- Anatomy and Physiology