Erythrocyte Cu/Zn Superoxide Dismutase Activity in Preterm Infants with and without Bronchopulmonary Dysplasia

Abstract

Background: Erythrocyte Cu/Zn superoxide dismutase is believed to play a major role as a first-line antioxidant defense. Studies have reported varying results from measures of superoxide dismutase activity in cord blood samples from neonates. Objective: The study goal was to assess enzyme activity for preterm infants representing a range of gestational ages during the 1st week of life. Clinical data were obtained and correlations with superoxide dismutase activity were examined. Methods: We collected blood samples from umbilical arterial lines or the radial artery of 44 preterm infants (gestational age range 25–30 weeks) on days 1, 3, and 6 after delivery and evaluated erythrocyte Cu/Zn superoxide dismutase activity. Results: There was no correlation between enzyme activity and gestational age or birth weight. Superoxide dismutase activity gradually increased in preterm infants with bronchopulmonary dysplasia on days 3 and 6, with levels significantly higher than those of preterm infants without bronchopulmonary dysplasia on day 6. We found that packed red cell transfusion did not affect erythrocyte superoxide dismutase activity in either group. However, higher cumulative oxygen administration was noted in preterm infants with bronchopulmonary dysplasia. Conclusion: Higher cumulative oxygen administration may be one factor that upregulates the activity of erythrocyte superoxide dismutase.