Table 3.

BAL, morphometry and stereology of mouse lungs exposed to 100% oxygen for 12, 24 and 48 h

Group	Control	12 h	24 h	48 h
IHI (%)	35.3 ± 2.9	47.7 ± 3.8	60.3 ± 2.3*	59.3 ± 7.2*
Macrophages (×103/ml)†	183.2 ± 7.6	205.8 ± 13.1	348.2 ± 14.4***	249.2 ± 14.8*
Neutrophils (×103/ml)†	30.1 ± 4.4	57.2 ± 4.6	257.0 ± 5.1***	348.4 ± 12.2***
Macrophages/mm2‡	197.5 ± 9.2	122.5 ± 11.9*	370.0 ± 20.2***	180.0 ± 21.2
Neutrophils/mm2‡	62.5 ± 3.2	13.7 ± 1.2***	111.0 ± 11.7**	211.0 ± 23.6***
Vv lung parenchyma (%)	50.5 ± 2.9	49.0 ± 3.3	57.2 ± 1.9	64.7 ± 3.2*

IHI, immunohistochemical index (AMs positive for TNF-α/total AMs) × 100; Vv, volume density; BAL, bronchoalveolar lavage.

^†Cell counts performed in BAL by using a Zi Coulter counter; differential cell counts were performed on cytospin preparations.

^‡Cell counts were performed in lung tissue by using a 40× objective lens on a video microscope linked to a colour video camera and a colour video monitor. Vv was performed using a 20× objective lens as described above.

For more details, see the Materials and Methods section. Values are the means ± standard error of the mean. For macrophages and neutrophils, we used a one-way anova followed by the Student–Newman–Keuls post hoc test. For IHI and Vv, we used the Kruskal–Wallis test followed by the Dunn’s post hoc test. In all instances, significance levels were set at 5%. *P < 0.05 compared to the control group; **P < 0.01 compared to the control group; ***P < 0.001 compared to the control group. N = 10 per group.