Role of spreading-factor (hyaluronidase) on bronchial response to acetylcholine challenge in dog

Patients with non-specific chronic lung diseases are very sensitive against external challenge. Experiments in human volunteers and in animals it has been shown that many substances can make bronchial system hyperreactive without causing any direct effect. The mechanisms involve in the process of hyperreactive bronchial system are, so far, not clear. It is conceived in this study that membrane permeability might play an important role in this process. This possibility has been studied in anesthetized dogs by subjecting them to hyaluronidase aerosol. This enzyme is supposed to change the membrane permeability by acting on the ground substance. The animals were first challenged with acetylcholine to obtain the basic responsiveness. Then the animals were subjected to hyaluronidase aerosol and challenged with acetylcholine again. Results confirm the hypotheses that membrane permeability plays an important role in hyperreactive bronchial system.