Figure 6: The effect of SS on SP in tracheal smooth muscle and lung. (a) The fluorescence photomicrographs of SP nerve fibers in tracheal epithelium (E) and smooth muscle (TSM) in 1 day and 5 days of FA or SS-exposed mice. Arrows: the localization of SP immunoreactive nerve fibers. (b) The changes of SP nerve fiber density in tracheal smooth muscle after FA (opened bar) or SS (closed bar) exposure. (c) The changes of SP in lung after FA (opened bar) or SS (closed bar) exposure measured by ELISA. Values are means SE; in each group. *Significant difference comparing corresponding data between FA and SS animals, .