Protective effect of surface-active phospholipids against the acid-inducing inhibition of the tracheal mucociliary transport.

Little is known about the physiological role of surface active phospholipids (SAP) in the central respiratory tract. In the present study, the effect of SAP on acid-inducing inhibition of particle transport by the tracheal mucociliary function was investigated in unanesthetized pigeons. SAP and acids were directly nebulized to the surface of the trachea. The composition of SAP was based on that of the pulmonary surfactant. The experiment was carried out under application of acetylcholine providing a constant mucociliary transport. SAP significantly diminished HCl- and H2SO4-inducing inhibitions of the mucociliary transport. Benzalkonium chloride also reduced the inhibition. The results suggest that SAP may be a protecting factor of the mucociliary clearance and that SAP may be connected with hydrophobicity not only of the alveolar surface but of the tracheal epithelium.