MOUSE STRAIN DIFFERENCES IN OZONE DOSIMETRY AND BODY-TEMPERATURE CHANGES

Strain differences in susceptibility to inhaled ozone (O-3) have been observed in mice, with C57BL/6J (B6) mice reported to be more sensitiv e than C3H/HEJ (C3) mice when exposed to equal concentrations of O-3. To determine whether differences in the delivered dose of O-3 to the l ung could help explain these differences, C3 and B6 mice were exposed to O-18-labeled ozone (O-18(3)), and the resulting O-18 concentrations in pulmonary tissues were monitored as an indicator of O-3 delivered dose. Body core temperatures (T-co) of similarly treated mice were mea sured during O-3 exposures (using surgically implanted temperature pro bes) in an effort to correlate lung O-3 dose to changes in basal metab olism. Immediately after exposure to O-18(3), C3 mice had 46% less O-1 8 (per mg dry wt) in lungs and 61% less in tracheas than B6 mice. Nasa l O-18 tended to be lower in the C3 mice, but these differences were n ot significant. Although both strains responded to the O-3 exposure wi th significant decreases in T-co, C3 mice had a 70% greater mean tempe rature X time product decrease during the exposure than B6 mice. These results suggest that the strain differences in O-3 susceptibility may be due to differences in O-3 dose to the lung, which may be related t o differences in the ability of the mice to lower their T-co in respon se to O-3 exposure.