Pulmonary surfactant: hydrophobic nature of the mucosal surface of the human amnion.

Abstract

SUMMARY1. The contact angle has been measured for a drop of saline placed upon the rinsed mucosal surface of the amnion in eleven human placental membranes obtained from normal births at full term.2. The contact angle averaged 700, indicating a hydrophobic surface comparable with graphite (860), polyethylene (940) or oxyntic tissue (850) which is also exposed to endogenous surface-active phospholipids in vivo.3. By comparison, four pre-term placentas with an average gestation period of 29-5 weeks gave a mean contact angle of 320, indicating that hydrophobicity of the placenta increases with maturity (41 weeks) and might well be imparted by adsorbed surfactants present in amniotic fluid and known to render other surfaces hydrophobic. 4. Since the mucosal epithelium of the amnion is exposed to the same surfactants in the same physical state as the fetal alveolar wall, the above results imply that this surface may also be hydrophobic, as indicated in the adult lung by other studies.5. The concept of surfactant directly adsorbed to the pulmonary tissue surfaces is discussed in connexion with its possible functional advantages in 'de-watering' the lung at birth, maintaining homeostasis by water repellency, releasing airway surfaces and lymph ducts glued by protein and lubricating tissue respiratory movement.

Hydrophobic Interactions: Role in Bacterial Adhesion

“…Similarly, despite the obviously hydrophobic surface properties of human skin and hair, we are not aware of extensive studies on the role of hydrophobic interactions in mediating bacterial adhesion to such surfaces. Do hydro-phobic pulmonary surfactants (Cotton and Hills, 1984) mediate or inhibit adhesion to lung tissues? Similarly, what is the role of hydrophobic interactions in mediating adhesion to aging or damaged cells and tissues, e.g., cornea?…”

Liquid plug propagation in computer-controlled microfluidic airway-on-a-chip with semi-circular microchannels

“…High-speed movies of the moving liquid plug, however, still show significant contact angle hysteresis especially for the advancing meniscus. While cell surfaces are often assumed to be highly hydrophilic, they can have relatively high contact angle and surface heterogeneity particularly for air-exposed tissues such as the amnion, 33 various gastrointestinal mucous-coated surfaces [34][35][36] and the air-exposed corneal epithelium. 37 Although measurements of pulmonary mucosa contact angle in the small airways are limited by the tissue's geometry, several tracheal studies have suggested that under healthy conditions the lung mucosa is relatively hydrophilic.…”