Surfactant and bronchial response

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A variety of clinical and experimental evidence indicates that surfactant may be important in the pathogenesis and treatment of asthma. The purpose of this study was to determine the effect of pulmonary surfactant and/or its components on precontracted rat bronchi. Left and right first generation bronchial tissues from male Sprague-Dawley rats were used in the studies done in vitro. Precontracted tissues were exposed to three kinds of surfactant: natural rat surfactant (NRS), bovine lipid extract surfactant (BLES), and Survanta. Surfactant was shown to relax rat bronchi in a concentration-dependent manner. The mechanism of surfactant-induced relaxation was determined. The surfactant relaxation response was inhibited when tissues were devoid of epithelium or when they were treated with indomethacin. N-co-nitro-L-arginine methyl ester (L-NAME) did not affect the surfactant-induced relaxation. Surfactant lipids, unsaturated phosphatidyicholine (uPC), dipalmitoylphosphatidylcholine (DPPC), and phosphatidyiglycerol (PG), and surfactant-specific protein A (SP-A) also showed a relaxant effect whereas non-surfactant lipids and proteins did not. We conclude that surfactant is an airway smooth muscle relaxant. The effect is specific and is dependent on the presence of epithelium and release of prostanoids, but is not dependent on the nitric oxide (NO) pathway.
Bibliography: p. 122-132
Koetzler, R. (2003). Surfactant and bronchial response (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from doi:10.11575/PRISM/16378