[Airway epithelium affects relaxing effect of verapamil]

The characteristic features of airway hyperreactivity disease are non-specific hyperresponsiveness, insensitive to spasmolysant and damage of epithelium. In our experiment, we measured the tension change of isolated trachea smooth muscle of guinea pig in reacting to acetylcholine and verapamil. It confirmed that (1) the removal of epithelium increases the reactivity of preparations to acetylcholine and reduces the effect of verapamil, (2) in above process the epithelium-derived relaxing factor (EpDRF) had participated in airway hyperreactivity and (3) EpDRF was not derived from metabolism of cyclooxygenase.