face), in the form of layers of vesicles. Schindler developed The surface pressure increase in suspensions of dimyristoyl/ a theoretical model for phospholipid deposition at the interpalmitoylphosphatidylcholine (DMPC/DPPC) and dioctadecylface, describing equilibrium states between vesicles right dimethylammonium chloride (DODA)Cl vesicles have been invesbeneath the surface and those in the bulk (2). Based on tigated as a function of temperature. The surface pressure (tenthese results, the transformation of closed bilayers into a sion), recorded on a Langmuir Balance (tensiometer) with continmonolayer became an alternative to study the the problem uous increase in temperature, changes abruptly at the gel B of the lung surfactant, since the phospholipid absorption liquid-crystalline transition temperature (T m ) of the vesicles. The at the air/water interface is basic to the comprehension of values of T m obtained by this fast and reproducible method are dynamic properties in the respiratory system (10, 11). This in good agreement with those determined by a variety of other techniques. α§ 1998 Academic Press technique is also of interest for the study of the interaction Key Words: vesicles; phase transition temperature; surface presbetween proteins and vesicles and their incorporation into sure.
phospholipids films formed due to the fusion of the vesicles with the air/water interface (12, 13).
In most of the investigations of vesicles fusion with the