SURFACE TENSION IN THE LUNG

I. Fundamental Studies on Measurement of Surface Activity

Abstract

Surface activity of the alveolar lining layer has been recently investigated in many laboratories. We are studying the change in surface activity in pathological conditions. In this study the fundamental problems in Pattle's method were investigated in which the surface activity was expressed by ‘stability ratio’ calculated by measurement of the change in size of bubbles obtained by squeezing a piece of lung tissue in a drop of air-saturated saline. (1) The bubbles produced from rabbit serum or lymph collected from right thoracic lymph duct of dog were unstable and were different from those obtained from normal lung which were stable and the SR was about 0.9. (2) There was no difference in SR among upper-, middle-, and lower parts of the lungs and between right and left lung. (3) There was no influence of pure oxygen or ether on SR when the duration of inhaltion of these gases was short. (4) Tween 20 lowered the SR to 0.39. (5) The SR fell remarkably after 24 hours when the lung was kept in room temperature (20°C) and after 4 days in the refrigerator (5°C), but there was no change in SR for 4 weeks when the lung was frozen.