Surface elastic properties of surfactant from the lungs of neonatal pigs.

The elasticity of surfactant films from the lungs of neonatal pigs was measured using a torsion elastometer. It was found that the elastic modulus of the films increased markedly as the surfactant concentration was raised. Increasing the temperature stepwise over the range 25--41 degrees C produced a decrease in the elastic modulus. In contrast, altering the pH of the subphase over the range 7.1--7.7 had no significant effect on film elasticity. The influence of surfactant films on pulmonary compliance is discussed.