Effects of recombinant human superoxide dismutase during reoxygenation with 21% or 100% oxygen after cerebral asphyxia in newborn piglets

Abstract

Objective: Superoxide radicals (O₂^-) are generated during reoxygenation following asphyxia, possibly more when higher concentrations of O₂ are used during resuscitation. Superoxide dismutase (SOD) is an antioxidant enzyme, which scavenges O₂^-. We tested the hypothesis that a single intravenous dose of recombinant human Cu,Zn SOD (rhSOD) could influence microcirculation and biochemical markers of asphyxia in piglets reoxygenated with 21% or 100% O₂ after combined cerebral hypoxemia-ischemia-hypercapnia. Methods: Anesthetized newborn piglets were randomized to asphyxia (n = 40) or control (n = 3). Asphyxia was induced by ventilation with 8% O₂, adding CO₂, and temporary occlusion of both common carotid arteries. After 20 min, 16 piglets received rhSOD 5 mg/kg intravenously and reoxygenation with 21% O₂ (rhSOD, 21%; n = 8) or 100% O₂ (rhSOD, 100%; n = 8), and 24 piglets received saline and reoxygenation with 21% O₂ (21%, n = 13) or 100% O₂ (100%, n = 11). The cortical microcirculation was assessed by laser Doppler flowmetry, and glutamate in the striatum and hypoxanthine in the cortex were measured by in vivo microdialysis. Results and conclusion: rhSOD peaked in plasma after 5 min. No rhSOD was detected in brain tissue. There were no significant differences between rhSOD and non-rhSOD groups in any measured variable.

• Antioxidant
• Cerebral Hypoxemia-Ischemia-Hypercapnia
• Newborn Piglets
• Reoxygenation-Reperfusion
• Superoxide Dismutase
• Superoxide Radicals