Consequences of Prolonged Inhalation of Ozone on F344/N Rats: CollaborativeStudies. Part 2. Mechanical Properties, Responses to Bronchoactive Stimuli, and Eicosanoid Release in Isolated Large and Small Airways

摘要

The overall conclusion of this multifaceted study was that prolonged ozoneexposure produced relatively few abnormalities in the basic contractile properties of rat airways, and few changes in their responses to stimulants. The large airways isolated from ozone-exposed rats, irrespective of the level of ozone exposure, showed no important differences from control values in either the active or passive contractile responses, or in the levels of eicosanoids released after stimulation. In contrast, some statistically significant changes were noted in the small airways from animals exposed to 0.5 ppm ozone. The thickness of the small airway wall in these specimens was increased approximately 40%, primarily because of an increase in the amount of smooth muscle. Surprisingly, however, the maximum stress generated in these airways was reduced in response to smooth muscle stimulators. It is not clear how these observations in isolated small airways relate to lung function in living animals. The clinical significance of these findings may become clearer when they are evaluated in conjunction with functional measurements that were made in the same animals by another group of investigators who participated in this project.