TY - JOUR
T1 - Liquid-crystalline collapse of pulmonary surfactant monolayers
AU - Schief, William R.
AU - Antia, Meher
AU - Discher, Bohdana M.
AU - Hall, Stephen B.
AU - Vogel, Viola
N1 - Funding Information:
These studies were supported by grants from the National Institutes of Health (HL 03502 and 60914), the Whitaker Foundation, and the American Lung Association of Oregon.
PY - 2003/6/1
Y1 - 2003/6/1
N2 - During exhalation, the surfactant film of lipids and proteins that coats the alveoli in the lung is compressed to high surface pressures, and can remain metastable for prolonged periods at pressures approaching 70 mN/m. Monolayers of calf lung surfactant extract (CLSE), however, collapse in vitro, during an initial compression at ∼45 mN/m. To gain information on the source of this discrepancy, we investigated how monolayers of CLSE collapse from the interface. Observations with fluorescence, Brewster angle, and light scattering microscopies show that monolayers containing CLSE, CLSE-cholesterol (20%), or binary mixtures of dipalmitoyl phosphatidylcholine(DPPC)-dihydrocholesterol all form bilayer disks that reside above the monolayer. Upon compression and expansion, lipids flow continuously from the monolayer into the disks, and vice versa. In several respects, the mode of collapse resembles the behavior of other amphiphiles that form smectic liquid-crystal phases. These findings suggest that components of surfactent films must collapse collectively rather than being squeezed out individually.
AB - During exhalation, the surfactant film of lipids and proteins that coats the alveoli in the lung is compressed to high surface pressures, and can remain metastable for prolonged periods at pressures approaching 70 mN/m. Monolayers of calf lung surfactant extract (CLSE), however, collapse in vitro, during an initial compression at ∼45 mN/m. To gain information on the source of this discrepancy, we investigated how monolayers of CLSE collapse from the interface. Observations with fluorescence, Brewster angle, and light scattering microscopies show that monolayers containing CLSE, CLSE-cholesterol (20%), or binary mixtures of dipalmitoyl phosphatidylcholine(DPPC)-dihydrocholesterol all form bilayer disks that reside above the monolayer. Upon compression and expansion, lipids flow continuously from the monolayer into the disks, and vice versa. In several respects, the mode of collapse resembles the behavior of other amphiphiles that form smectic liquid-crystal phases. These findings suggest that components of surfactent films must collapse collectively rather than being squeezed out individually.
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U2 - 10.1016/S0006-3495(03)75107-8
DO - 10.1016/S0006-3495(03)75107-8
M3 - Article
C2 - 12770885
AN - SCOPUS:0037763970
SN - 0006-3495
VL - 84
SP - 3792
EP - 3806
JO - Biophysical Journal
JF - Biophysical Journal
IS - 6
ER -