Segregated phases in pulmonary surfactant membranes do not show coexistence of lipid populations with differentiated dynamic properties

J. BERNARDINO DE LA SERNA; G. ORÄDD; LUIS A. BAGATOLLI; A.C. SIMONSEN; D. MARSH; G. LINDBLOM; J. PEREZ-GIL

BIOPHYSICAL JOURNAL

CELL PRESS

Lugar: United States; Año: 2009 vol. 97 p. 1381 - 1381

0006-3495

he composition of pulmonary surfactant membranes and films has evolved to support a complex lateral structure, including segregation of ordered/disordered phases maintained up to physiological temperatures. In this study, we have analyzed the temperature-dependent dynamic properties of native surfactant membranes and membranes reconstituted from two surfactant hydrophobic fractions (i.e., all the lipids plus the hydrophobic proteins SP-B and SP-C, or only the total lipid fraction). These preparations show micrometer-sized fluid ordered/disordered phase coexistence, associated with a broad endothermic transition ending close to 37 degrees C. However, both types of membrane exhibit uniform lipid mobility when analyzed by electron paramagnetic resonance with different spin-labeled phospholipids. A similar feature is observed with pulse-field gradient NMR experiments on oriented membranes reconstituted from the two types of surfactant hydrophobic extract. These latter results suggest that