We ventilated excised rat lungs at a constant tidal volume (CTV); they developed areas of atelectasis which could be reversed by a large inflation (CTV + I) or prevented by the addition of positive end-expiratory pressure to the CTV. To explore the possibility that these modes of ventilation led to changes in surfactant, we lavaged the lungs and centrifuged the returns at 500 g; we measured the amount of disaturated phosphatidylcholine (DSPC) in the resultant pellet and supernatant fluid as a marker for surfactant. We found 16.9±1.5 (mean±SE), 38.0±2.4, 18.3±1.6, and 21.7±2.3% of the total lavage DSPC, in the pellet from freshly excised, CTV, CTV + I, and positive end-expiratory pressure to the CTV lungs, respectively. The total amount of lavage DSPC was the same in all groups.
Lyn Aung Thet, Linda Clerch, Gloria D. Massaro, Donald Massaro