| Abstract: | We studied the influence of respiratory epithelium on tracheal smooth muscle tone of guinea pigs. Mechanical removal of the epithelium induced an increase of the contractile response to histamine. In preparation of smooth muscle previously contracted by histamine, isoproterenol induced dose--dependent relaxation, the level of which was significantly greater in tracheal smooth muscle with epithelium than without it. These results suggest an important role of respiratory epithelium on the contractile activity of smooth muscle. |
