Abstract
Monomolecular films of phospholipids in the liquid-expanded (LE) phase after supercompression to high surface pressures (π), well above the equilibrium surface pressure (πe) 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 π above πe. 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 π, in contrast to 1-palmitoyl-2-oleoyl phosphatidylcholine, for which higher π produced collapse at lower temperatures. For π between 50 and 65 mN/m, DPPC melted at 48-55° C, well above the main transition for bilayers at 41° C. At each π, 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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1739-1745 |
| Number of pages | 7 |
| Journal | Journal of Applied Physiology |
| Volume | 102 |
| Issue number | 5 |
| DOIs | |
| State | Published - May 2007 |
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Keywords
- Captive bubble
- Dipalmitoyl phosphatidylcholine
- Jammed
- Monolayer
- Pulmonary mechanics
- Supercompressed
ASJC Scopus subject areas
- Physiology
- Endocrinology
- Orthopedics and Sports Medicine
- Physical Therapy, Sports Therapy and Rehabilitation
Cite this
The melting of pulmonary surfactant monolayers. / Yan, Wenfei; Biswas, Samares C.; Laderas, Ted G.; Hall, Stephen (Steve).
In: Journal of Applied Physiology, Vol. 102, No. 5, 05.2007, p. 1739-1745.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The melting of pulmonary surfactant monolayers
AU - Yan, Wenfei
AU - Biswas, Samares C.
AU - Laderas, Ted G.
AU - Hall, Stephen (Steve)
PY - 2007/5
Y1 - 2007/5
N2 - Monomolecular films of phospholipids in the liquid-expanded (LE) phase after supercompression to high surface pressures (π), well above the equilibrium surface pressure (πe) 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 π above πe. 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 π, in contrast to 1-palmitoyl-2-oleoyl phosphatidylcholine, for which higher π produced collapse at lower temperatures. For π between 50 and 65 mN/m, DPPC melted at 48-55° C, well above the main transition for bilayers at 41° C. At each π, 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.
AB - Monomolecular films of phospholipids in the liquid-expanded (LE) phase after supercompression to high surface pressures (π), well above the equilibrium surface pressure (πe) 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 π above πe. 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 π, in contrast to 1-palmitoyl-2-oleoyl phosphatidylcholine, for which higher π produced collapse at lower temperatures. For π between 50 and 65 mN/m, DPPC melted at 48-55° C, well above the main transition for bilayers at 41° C. At each π, 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.
KW - Captive bubble
KW - Dipalmitoyl phosphatidylcholine
KW - Jammed
KW - Monolayer
KW - Pulmonary mechanics
KW - Supercompressed
UR - http://www.scopus.com/inward/record.url?scp=34247889888&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34247889888&partnerID=8YFLogxK
U2 - 10.1152/japplphysiol.00948.2006
DO - 10.1152/japplphysiol.00948.2006
M3 - Article
VL - 102
SP - 1739
EP - 1745
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
SN - 8750-7587
IS - 5
ER -