Role of surface tension lowering substances in the function of normal and diseased eustachian tubes of guinea pigs

Abstract

To examine the role of surface tension lowering substances (STLSs), we measured changes in passive opening pressure (OP) and closing pressure (CP) in eustachian tubes of guinea pigs before and after washing the tubes with various solutions (saline solution, artificial pulmonary surfactant, synthetic phospholipids, and detergent)). The percent decreases in OP and CP in tubes washed with artificial surfactant were significantly higher than those washed with saline solution. Those washed with synthetic phospholipids or detergent (Triton X-100) did not differ from those washed with saline solution. In guinea pigs with experimental otitis media produced by inoculation of formalin-killed Haemophilus influenzae into the middle ear cavity, the percent decreases in OP and CP in tubes washed with artificial pulmonary surfactant were significantly higher than in those washed with saline solution. Artificial pulmonary surfactant was injected into the middle ear cavity of the guinea pigs with otitis media. At 5 days after inoculation, the inflammatory changes of the middle ear were much milder in animals with intratemporal application of artificial pulmonary surfactant than in those with saline application. These results suggest the possible efficacy of treatment with artificial pulmonary surfactant for otitis media.