HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 102/5/1739    most recent 00948.2006v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Yan, W. Articles by Hall, S. B. Search for Related Content PubMed PubMed Citation Articles by Yan, W. Articles by Hall, S. B.

The melting of pulmonary surfactant monolayers

Departments of Biochemistry & Molecular Biology, Medicine, and Physiology & Pharmacology, Oregon Health & Science University, Portland, Oregon

Submitted 27 August 2006 ; accepted in final form 20 December 2006

Monomolecular films of phospholipids in the liquid-expanded (LE) phase after supercompression to high surface pressures (), well above the equilibrium surface pressure (_e) at which fluid films collapse from the interface to form a three-dimensional bulk phase, and in the tilted-condensed (TC) phase both replicate the resistance to collapse that is characteristic of alveolar films in the lungs. To provide the basis for determining which film is present in the alveolus, we measured the melting characteristics of monolayers containing TC dipalmitoyl phosphatidylcholine (DPPC), as well as supercompressed 1-palmitoyl-2-oleoyl phosphatidylcholine and calf lung surfactant extract (CLSE). Films generated by appropriate manipulations on a captive bubble were heated from 27°C to 60°C at different constant above _e. DPPC showed the abrupt expansion expected for the TC-LE phase transition, followed by the contraction produced by collapse. Supercompressed CLSE showed no evidence of the TC-LE expansion, arguing that supercompression did not simply convert the mixed lipid film to TC DPPC. For both DPPC and CLSE, the melting point, taken as the temperature at which collapse began, increased at higher , in contrast to 1-palmitoyl-2-oleoyl phosphatidylcholine, for which higher produced collapse at lower temperatures. For between 50 and 65 mN/m, DPPC melted at 48–55°C, well above the main transition for bilayers at 41°C. At each , CLSE melted at temperatures >10°C lower. The distinct melting points for TC DPPC and supercompressed CLSE provide the basis by which the nature of the alveolar film might be determined from the temperature-dependence of pulmonary mechanics.

captive bubble; dipalmitoyl phosphatidylcholine; jammed; monolayer; pulmonary mechanics; supercompressed

This article has been cited by other articles:

				S. Orgeig, W. Bernhard, S. C. Biswas, C. B. Daniels, S. B. Hall, S. K. Hetz, C. J. Lang, J. N. Maina, A. K. Panda, J. Perez-Gil, et al. The anatomy, physics, and physiology of gas exchange surfaces: is there a universal function for pulmonary surfactant in animal respiratory structures? Integr. Comp. Biol., October 1, 2007; 47(4): 610 - 627. [Abstract] [Full Text] [PDF]