Levels of (A, C) unmetabolized and (B, D) GSH-conjugated NA in plasma and lung tissue. Levels of unmetabolized NA were low in juvenile lung tissue (ng/g) and high in juvenile plasma (ng/ml). Neonatal mice had high levels of NA-GSH (ng/g) in lung tissue, but this group had the lowest levels of NA-GSH in plasma (ng/ml). Tissue collected 0–15 min after 10 ppm × 4 h exposure. NA concentration in juvenile female plasma was significantly higher than in juvenile males and female neonatal mice. Statistics (n = 6–8): 2-way ANOVA (age, sex) with Tukey’s post hoc test (*p < .05, **p < .01, ***p < .001, ****p < .0001; #, significantly greater than juvenile male, p = .0065).