OZONE-INDUCED ALTERATION IN BETA-ADRENERGIC PHARMACOLOGICAL MODULATION OF PULMONARY MACROPHAGES

Ozone is a ubiquitous air pollutant which can affect numerous function s of the respiratory system. However, previous work has not provided a ny information concerning its ability to modulate pharmacological rece ptors of pulmonary macrophages. This study examined, using a chemilumi nescence assay, the beta-adrenergic modulation of pulmonary macrophage s harvested from rabbits exposed for 3 hr/day for 5 days to 0.1, 0.3 o r 0.6 ppm ozone (O-3) or to 3 hr/day for 20 days to 0.1 or 0.3 ppm. Re ceptor activity was monitored using release of reactive oxygen species (ROS) following administration to the cells of the beta(2)-receptor a gonist, isoproterenol. An O-3-exposure concentration-dependent respons e was observed for isoproterenol efficacy following 5-day exposures, i n that 0.1 ppm O-3 induced a significant enhancement of beta-adrenergi c inhibition of ROS production, 0.3 ppm ozone produced no significant change from control, and 0.6 ppm decreased inhibition. No significant effects on beta-adrenergic modulation were noted following the 20-day exposures. The results of this study suggest that short-term repeated exposures to O-3 are capable of inducing alterations in the pharmacolo gical functioning of pulmonary macrophages, while longer term exposure s may result in adaptation. Alterations in receptor function have impl ications in terms of pulmonary defense and disease. (C) 1996 Academic Press, Inc.