Hypoxic challenge of hyperoxic pulmonary artery myocytes increases oxidative stress due to impaired mitochondrial superoxide dismutase activity.

Infants with lung disease may be exposed to high O2 concentrations, and may have transient hypoxic episodes due to worsening lung pathophysiology, aggravating pulmonary arterial (PA) oxidative stress. NADPH oxidase (NOX) converts O2 to superoxide. Mitochondrial antioxidants such as superoxide dismutase (SOD) are sensitive to O2 tension. We previously reported decreased SOD2 activity in hypoxic PA myocytes due to nitration. In this study, we examined whether a transient hypoxic episode exposes antioxidant defense defects in hyperoxic PA myocytes.