Structural studies on lamellated osmiophilic bodies isolated from pig lung. 31P NMR results and water content

Lipid polymorphism and the functional roles of lipids in biological membranes

“…These results, which are substantiated to some extent by recent unpublished work in the author's laboratories, are particularly intriguing in the light of the ongoing controversy concerning the structure of the inner mitochondrial membrane [88]. Finally, in osmiophilic bodies from porcine lung about 5% of the phospholipid undergoes isotropic motion which has been suggested to be due to the influence of apolar proteins [89].…”

EXOCYTOSIS OF LUNG SURFACTANT: From the Secretory Vesicle to the Air-Liquid Interface

“…However, an accurate determination even of this bulk composition is not trivial to perform, and many factors, such as osmolarity, are not precisely known. The aqueous phase of LBs, in turn, is even more inaccessible to analysis, but a water content of ∼15% has been inferred from NMR studies (135). The water is located between the lipid bilayers and might be immobilized by hydration to the phospholipid head groups.…”

“…Certainly, the transit of material from LBPs into the alveolar air-liquid interface is not instantaneous (135). The turnover time of LBPs in the lung has been estimated to be of the order of ∼0.7 h (145).…”

31P NMR spectroscopy of isolated perfused lungs

“…The spectrum also contains a very broad component (-500 Hz) which may be due to membrane phospholipids or protein-bound phosphorus metabolites. Phosphatidy1 choline has been identified as a major component of pulmonary surfactant in pig lungs and reported to have a very broad 31P NMR spectrum (16). During perfusion with oxygenated blood, ATP levels remained stable within 10% for more than 4 h. Little change was seen in the intensities of the various peaks in the spectrum during perfusion with 3% dextran in saline, indicating that blood contributes little to the spectrum.…”