Protease-induced experimental emphysema: the relationship between elastolytic activity and emphysema induction.

Induction of experimental emphysema by protease was performed with several proteases both in vivo and in vitro to compare the ability of inducing emphysematous change and their elastolytic activity. The following results were obtained. 1) Only elastase and papain have emphysema inducing capacity. Emphysematous changes induced by elastase in vitro were dose dependent. But papain has no genuine elastolytic activity. Nature of the emphysema-inducing capacity of papain remains obscure. 2) Advantages of using the isolated lung for experiment were discussed, especially for the small dose required for enzyme-instillation. Moreover, there is no interferencey by endogeneous enzyme or protease-inhibitors. 3) Guinea pig is useful for the experiemnt of emphysema-induction both in vivo and in vitro. Minimal requirement of elastase is 50 microgram in vitro and 250 microgram for in vivo experiment.