Incorporation and disappearance of oxygen-18 in lung from mice exposed to 1 ppm (18)O3(1)

In the study, (18)O(3) was used as a tracer for inhaled ozone in mice. The amount of ozone-derived oxygen (ODO) in the lungs was determined by measuring the amount of oxygen-18 in excess of the natural abundance level which remained covalently bound to organic constituents of lung tissue following exposure to 1 ppm (18)O(3). The rate of disappearance of ODO from the lungs was determined by quantifying the rate of decrease of oxygen-18 in excess of the natural abundance level in lung tissue from mice exposed to 1 ppm (18)O(3) for 45 min. With exposure to 1 ppm (18)O(3), ozone-derived oxygen accumulated in lung tissue at a rate of 4.38 pmoles of ODO/mg/min. ODO had a half-life in lung tissue of approximately 6 h. It was impossible to determine accurately the dose of ozone to tissue from these data. However, it was estimated that in each animal a minimum of 44 pmoles of O(3) reacted with molecular constituents of lung tissue every minute of exposure to 1 ppm O(3)