The contact angle induced by DPL at pulmonary epithelial surfaces

Area of Science:

• Pulmonary Physiology
• Surface Chemistry
• Biophysics

Background:

• The lung's surface properties are crucial for maintaining airway patency and function.
• Dipalmitoylphosphatidylcholine (DPL) is a major component of pulmonary surfactant, influencing surface tension.
• Understanding DPL's interaction with the tracheal epithelium is key to respiratory health.

Purpose of the Study:

• To measure the contact angle at the dog tracheal epithelium surface.
• To investigate the effect of DPL on surface tension and wettability.
• To explore the physiological implications of DPL's surface properties.

Main Methods:

• Contact angle measurement using two surface balances in a Langmuir trough.
• Simultaneous monitoring of apparent surface tension.
• Direct observation for confirmation.

Main Results:

• Ringer's solution alone did not induce a contact angle.
• DPL induced a contact angle on the fluid surface at physiological concentrations.
• Contact angle varied from 9 to 67 degrees with film compression, showing hysteresis.
• DPL reduced surface tension while decreasing wettability, acting as an anti-wetting agent.

Conclusions:

• DPL exhibits unusual surface properties, reducing surface tension but decreasing wettability.
• This anti-wetting property may facilitate mucus propulsion by differential cilia wettability.
• Potential disadvantage: DPL could form fluid plugs sealing airways, particularly in newborns.