Effect of Bovine Surfactant on Mucus Secretion from Tracheal Submucosal Glands

Abstract

Although the stabilizing effect of surface active material on alveolar structures is well established much less is known about possible effects of surfactant on small and, especially, on large bronchi. The question is of interest because surface active material has been identified in bronchial secretions [1, 6, 9, 11]. In patients with asthma and cystic fibrosis, lipids constituted 30–40% of the dry insoluble material obtained from lavage specimens [11] and the high lipid content of bronchial secretions has been confirmed by many investigators [2]. One would expect therefore that surface active materials have a function in conducting airways as well as in the alveoli. The closure of small (< 0 5 mm) airways may be prevented by surfactant [8]. Effects on epithelial transport functions have been considered because myelin-figured lamallae have been found in the lower zone of the mucous blanket [13] and the presence of surface active material between the sol and the gel phase of bronchial mucus seems likely from these and other studies. This may aid in maintaining continuity of the mucus layer. Stimulation of surfactant production by inhaled corticosteroids decreased the viscosity of mucus [7]. Effects on physical properties of mucus and on the interface between the ciliary layer and the mucous blanket can be expected to affect the mucociliary system of the conducting airways.