The detrimental effect of serum albumin on the re-spreading of a dipalmitoyl phosphatidylcholine Langmuir monolayer is counteracted by a fluorocarbon gas

• Published in: Biochimica et biophysica acta 2007-03, Vol.1768 (3), p.490-494
• Main Authors: Gerber, Frédéric, Krafft, Marie Pierre, Vandamme, Thierry F.
• Format: Article
• Language: English
• Subjects: 1,2-Dipalmitoylphosphatidylcholine - chemistry; Acute respiratory distress syndrome; Animals; Cattle; Chemical Sciences; Dipalmitoyl phosphatidylcholine; Fluorescence microscopy; Fluorocarbon; Fluorocarbons; Gases; Langmuir monolayer; Lung surfactant; Material chemistry; Microscopy, Fluorescence; Perfluorooctyl bromide; Phase Transition; Serum albumin; Serum Albumin, Bovine - chemistry; Water - chemistry
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/j.bbamem.2006.09.022

We have recently reported that fluorocarbon gases exhibit an effective fluidizing effect on Langmuir monolayers of dipalmitoyl phosphatidylcholine (DPPC), preventing them from crystallizing up to surface pressures of ∼ 40 mN m − 1 , i.e. well above the DPPC's equilibrium surface pressure. We now report that gaseous perfluorooctyl bromide (gPFOB) promotes the re-spreading of DPPC Langmuir monolayers compressed on a bovine serum albumin (BSA)-containing sub-phase. The latter protein is known to maintain a concentration-dependent surface pressure that can exceed the re-spreading pressure of collapsed monolayers. This phenomenon was proposed to be responsible for lung surfactant inactivation. Compression/expansion isotherms and fluorescence microscopy experiments were carried out to assess the monolayers' physical state. We have found that, during expansion under gPFOB-containing air, the surface pressure of a DPPC monolayer on a BSA-containing sub-phase decreased to much lower values than when the DPPC monolayer was expanded in the presence of BSA under air (∼ 0 mN m − 1 vs. ∼ 7.5 mN m − 1 at 120 Å 2, respectively). Moreover, fluorescence images showed that, during expansion, the BSA-coupled DPPC monolayers, in contact with gPFOB, remained in the liquid-expanded state for surface pressures lower than 10 mN m − 1 , whereas they were in a liquid-condensed semi-crystalline state, even at large molecular areas (120 Å 2), when expanded under air. The re-incorporation of the PFOB molecules in the DPPC monolayer during expansion thus competes with the re-incorporation of BSA, thus preventing the latter from penetrating into the DPPC monolayer. We suggest that combinations of DPPC and a fluorocarbon gas may be useful in the treatment of lung conditions resulting from a deterioration of the native lung surfactant function due to plasma proteins, such as in the acute respiratory distress syndrome.