(116m) The Effect of Cholesterol on Lung Surfactant

Lung surfactant (LS) is a complex collection of proteins and lipids found at the interface between air and the pulmonary fluid that lines the inside surfaces of the alveoli in mammalian lungs. The vital functions of lung surfactant are disrupted by Acute Respiratory Syndrome (ARDS), a condition in which serum proteins replace LS molecules on the interface following acute trauma to the abdomen. No effective treatment for ARDS exists and the crucial need for a synthetic LS-like preparation, able to restore function to serum-disabled LS, is of paramount importance to the effort to lower the 30% mortality rate of this fatal condition. An important question in the design of an ARDS treatment is weather cholesterol should be included. Although known to be present in mammalian lungs, the role that cholesterol plays in functional LS is almost totally unknown.

In this study the effect of cholesterol on bovine-derived LS was investigated with fluorescence microscopy, atomic force microscopy, Wilhelmy-plate surface force measurements, and surface viscometry. The effect of cholesterol on the phase behavior of LS during the breathing cycle is discussed, speculations are offered on the interactions between cholesterol and the surfactant proteins.