Asthma is a chronic inflammatory disease characterized by airway hyperresponsiveness. Asthmatic airway is thickened and stiffened by remodeling. Many folds on the surface of airway appear by the constriction of smooth muscle and buckles. Because, the number of occurring folds decreases in the asthmatic airway, and the airway lumen becomes stenosed. As a result, it is thought that the breathing difficulties occur. It is important to clarify the buckling mechanism in the airway. In this study, to clarify the mechanism of the buckling, we used two-layered collapsible tubes as a model of the bronchiole and used a shock tube which gave a sudden decreasing in the pressure inside the tube. The tube cross-section area was visualized by using laser sheet technique, and a high speed video camera. As a result, the number of folds increased with increase in the elastic ratio.
