[Tension activity of pulmonary surfactant: adsorption of liposomes of model phospholipids].
One peculiarity of pulmonary surfactant, which is the tensioactive material physiologically present at the surface of alveoli, lies in its very quick localization at in the air-water interface. This being one of the limiting factors of artificial exogenous surfactants for the treatment of patients suffering of respiratory distress syndromes, we have studied the mechanisms which are intervening in the adsorption kinetics of a pure liquid--phase phospholipid, the dioleylphosphatidylcholine (DOPC), and of mixtures of dipalmitoylphosphatidylcholine (DPPC) and phosphatidic acid (PA) in presence of divalent cations (Ca++ and Mg++). The adsorption kinetics of liposomal suspensions of DOPC, which were studied by the Wilhelmy plate method, are determined by the existence of a barrier potential which height depends on the temperature and medium osmolarity, and on the deformability of vesicules. The study of PA-DPPC liposomes was performed with the help of a pulsating bubble surfactometer, a physicochemical instrumentation which mimics the pulmonary alveoli. To obtain performant responses with this model, high concentrations of PA and of divalent cations Ca++ and Mg++ are needed. These results, which are similar to those observed during the study of liposomal fusion, allow to propose a model, according to which adsorption of liposomes at the air-water interface is comparable to liposomal fusion and may be related to the presence of a thin aqueous film.
Denizot
B A
BA
Laboratoire de Physicochimie des Surfaces, Faculté de Pharmacie, Châtenay-Malabry.
Fain
B
B
Tchoreloff
P C
PC
Bonanno
L M
LM
Proust
J E
JE
Lindenbaum
A
A
Dehan
M
M
Puisieux
F
F
D000327:Adsorption / Q000187:drug effects; D008081:Liposomes; D008956:Models, Chemical; D010743:Phospholipids / Q000493:pharmacokinetics*; D011663:Pulmonary Surfactants / Q000494:pharmacology*
D008081:Liposomes; D010743:Phospholipids; D011663:Pulmonary Surfactants
Tensioactivié du surfactant pulmonaire: adsorption de liposomes de phospholipides modèles.