An emphysema model in rats treated intratracheally with elastase.

Pulmonary functions, morphology, and morphometry were examined in rats at 3, 7, and 10 weeks after a single intratracheal administration of 6.5 units of porcine pancreatic elastase in order to obtain a model of pulmonary emphysema which would be suitable for studying the responses of emphysematous lungs to atmospheric pollutants. Functional residual capacity and residual volume of the elastase-treated rats increased at all the times studied, but their total lung capacity increased only at 7 and 10 weeks compared with those of the saline-treated control rats. The increase in static lung compliance and the decrease in peak flow and maximum flow at 50% of total lung capacity during forced expiration were also observed in all except the 3-week elastase animals. The elastase-treated lungs showed morphological changes characteristic of emphysematous lesions. The increase in mean linear intercept length and the decrease in total alveolar surface area were demonstrated by these elastase-treated lungs. Based on these results, we conclude that an adequate and suitable model of pulmonary emphysema could be obtained in rats 7-10 weeks after treatment with the present dose of elastase.