Postmortem effects on the yield and composition of alveolar surfactant from rat lungs

Isolation of alveolar surfactant from human cadaver lungs might be ineffective because of postmortem effects. We studied therefore in the rat the effect of autolysis on the yield and composition of alveolar surfactant at different intervals after death. The total amount of phospholipids in the lavage fluids decreased at 4 h postmortem and increased thereafter again. Increased amounts of proteins, significant deviations from the normal phospholipid composition of surfactant and decreased surface activity were already present from 2 h onwards. However, a normal alveolar surfactant can be obtained up to 16 h after death by using a sucrose gradient centrifugation procedure. With this procedure it is possible to isolate a surfactant with adequate surface activity from mildly, but not from severely autolytic rat lungs.