Plasmalogens reduce the viscosity of a surfactant-like phospholipid monolayer

In this study, plasmalogen-free and plasmalogen-containing phospholipid (PL ) mixtures were investigated, using the Wilhelmy balance and an oscillating drop surfactometer (ODS). Plasmalogen-containing films showed very low vis cosity at very low surface tension compared with plasmalogen-free films. Te n mol% plasmalogens reduced the surface tension of the surfactant-like PL f ilm containing 70 mol% dipalmitoyl phosphatidylcholine (PtdCho) from 47.8 /- 0.9 to 25.7 +/- 0.8 mN/m. At these surface tensions the viscosity of the plasmalogen-containing monolayer was reduced by a factor of six. The visco sity of PL films that contain plasmalogens in the range of natural surfacta nt (2.5 mol%) was only half as high as plasmalogen-free PL films. These res ults suggest that monolayers of natural surfactant containing sufficient am ounts of plasmalogens remain fluid in the final phase of expiration. These properties of a surfactant monolayer can facilitate the formation of a film reservoir during expiration and the re-spread of that film material during inspiration without him fragmentation. (C) 1999 Elsevier Science Ireland L td. All rights reserved.