EVALUATION OF PRESSURE-DRIVEN CAPTIVE BUBBLE SURFACTOMETER

We modified the captive bubble surfactometer S. Schurch et al. J. App l. Physiol. 67: 2389-2396, 1989 to facilitate the measurement of surf ace adsorption rates and to simplify its construction. We used a range of standards and monolayers of dipalmitoylphosphatidylcholine to chec k the calibration of the device against measurements made in a Wilhelm y surface balance and in the captive bubble by using a cathetometer, a nd we found good agreement. As a further test we measured the surface properties of rabbit lavage lung surfactant (60,000 X average g for 60 min) at 1.0 mg phospholipid/ml. This material adsorbed within 1 s to near-equilibrium surface tension, reached surface tensions of <5 mN/m on the second compression, and formed very stable films. We conclude t hat a captive bubble surfactometer can provide accurate information ab out important surface properties of lung surfactant films.