Pulmonary response to exposure to ozone of emphysematous rats

Rats were treated with a single intratracheal instillation of 6.5 units elastase or normal saline. Seven weeks after treatment, the animals were exposed for 24 hr to filtered air or 1 ppm O3, and their lung functions were measured. The exposure to O3 resulted in functional changes depending mainly on peripheral airway obstruction, and the direction and degree of those functional changes were in general similar between the saline- and elastase-treated animals. Another group of saline- or elastase-treated rats were exposed to 3 ppm O3 for 3 hr and the edematous response of their lungs was again similar. These results indicate that elastase-treated lungs responded to the exposure to O3 in a fashion similar to normal lungs in rats, but lung damage caused by the exposure to O3 superimposed over preexisting emphysematous damage, resulted in an additional lessening of the margin of pulmonary reserve capacity.