Influence of pH and temperature on behaviour of surfactant from human neonatal lungs.

The surface pressures of human surfactant films were measured under static conditions and under dynamic (expansion-compression) conditions. The results from both methods showed that the maximum surface pressures generated by surfactant films in vitro were strongly dependent on temperature throughout the range 29-41 degrees C, higher pressures being achieved at the lower temperatures. In contrast, increasing the pH of the subphase stepwise over the range 7.1-7.7 produced a modest fall in the maximum pressures exerted by the films. The possibility that surfactant films may behave in a similar manner in vivo is discussed.