Medical Bulletin

Surfactants (an abbreviation of “surface active agent”) are substances that lower the surface tension of the fluid they are adsorbed or dissolved in, thereby enabling it to spread over surfaces more readily. This characteristic plays a crucial role in pulmonary physiology. Alveolar type II epithelial cells of the lungs produce pulmonary surfactant which by decreasing surface tension in the alveoli, counteracts the tendency of lung tissue to collapse and stabilises the lung volume at low trans-pulmonary pressures.1 Natural pulmonary surfactant comprises approximately 80 % phospholipids, 8 % neutral lipids, and 12 % protein. One of the components crucial in reducing surface tension is dipalmitoylphosphatidylcholine (DPPC). This is an amphipathic molecule with a polar hydrophilic head and a non-polar hydrophobic tail. The amphipathic nature of DPPC allows it to be adsorbed at the pulmonary air/liquid interface and reduces the tendency of alveolar collapse. Four unique surfactant-associated proteins have bee