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

In this study, 18O3 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 following exposure to 1 ppm 18O3 for less than or equal to 60 min. 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 from mice exposed to 1 ppm 18O3 for 45 min. With exposure to 1 ppm 18O3. ODO accumulated in lung at a rate of 4.38 pmol/mg dry weight/min. Ozone-derived oxygen had a half-life in lung of approximately 6 hr. We estimate that a minimum of 44 pmol of O3 reacted with lung every minute of exposure to 1 ppm O3.