Effect of inhaled ozone on lung histamine in conscious guinea pigs

The effect of short-term ozone (O3) exposure on pulmonary mast cell function was examined. Guinea pigs were continuously exposed to 1.0 ppm O3 for 2, 4, and 8 hr. O3 exposure produced a significant decrease in lung histamine concentration. Two-hour exposure to O3 caused a 22.4 +/- 7.0% decrease in lung histamine concentration compared with controls. Ozone exposures of 4 and 8 hr caused lung histamine concentrations to decrease by 43.7 +/- 7.7 and 49.0 +/- 7.5% (P less than 0.05), respectively, without significant changes in lung water or protein, or evidence of cytotoxicity. These results suggest that O3 or its metabolites affect pulmonary mast cell function by stimulating the release of histamine from the lung.