Hydrogen Peroxide Release from Alveolar Macrophages and Alveolar Type II Cells During Adaptation to Hyperoxia in Vivo

The effect of hyperoxia (1–14 days, 85% O2) on rat alveolar macrophage and alveolar type II cell oxidant and antioxidant characteristics was investigated. Unstimulated control macrophages (2 h ex vivo) released hydrogen peroxide at a rate of 3.5 ± 1.3 nmol/min mg protein−1 which was a cyanide-sensitive process. H2O2 release from alveolar macrophages decreased slightly but not significantly after 1 day in hyperoxia and increased significantly after 3 days (180%, p < .05) and 14 days (380%, p < .01). When H2O2 release was expressed as nmol from total macrophages per animal, the increase after 14 days in hyperoxia was 760%. H2O2 generation by hyperoxic macrophages was cyanide resistant, indicating the involvement of active NADPH oxidase. In both control and hyperoxic macrophages H2O2 release could be significantly stimulated with phorbol myristate acetate (PMA). Comparisons of H2O2 release by freshly isolated alveolar macrophages and alveolar type II cells must be cautiously interpreted because some cell fun...