THE ERYTHROCYTE OXIDATIVE STRESS DURING THE EARLY NEONATAL PERIOD. ▴ 1702

Abstract

Neonatal erythrocyte is frequently exposed to conditions associated with increased generation of oxygen free radicals, such as ischemia-reperfusion, hyperoxia and high free iron levels. Although detailed informations are available on the characteristics of neonatal erythrocytes, the real extent of oxygen toxicity to the red cell “in vivo” is still uncertain. In the present study we investigated red cell oxidative stress, as a function of intraerythrocyte free iron concentration (IFIC) and hypoxanthine plasma level(HyPL), during the early neonatal period. Heparinized blood samples were obtained from 163 newborn infants (gestational age (GA) 23-42 wk; birth weight 600-4950 g) at birth (cord blood: CB) and on the fourth day of life (4d). 101(A group) had a GA ≥ 37 wk and mean birth weight of 3328 ± 473g; 62(B group) GA < 37 wk and mean birth weight of 1690 ± 473 g(x ± SD). IFICs (nmol/ml) and HyPLs (μg/ml) were determined by HPLC. The IFICs in CB and blood of 4 day-old infants were significantly higher in group B (CB: 7.2±3.7; 4d: 8.3±6.8) than in group A (CB: 4.3±4.4; 4d: 3.2±2.3; p<0.0001). Higher HyPLs were also observed in group B than in group A at birth (8.8 vs 6.3 p<0.03). Babies who needed neonatal resuscitation showed at birth higher IFIC(9±5 vs 3.7±2.4; p<0.0001) and HyPL (9.9±3.9 vs 4.5±2.4; p<0.0001) than those who didn' t. Negative correlations were detected: 1) between IFIC and GA both at birth (r= -0.42, p < 0.0001) and on the 4th day of life (r= -0.52, p < 0.0001), 2) between HyPLs in cord blood and GA (r=-0.33, p<0.01); 3) between Apgar score at 1 min. and IFIC in CB (r= -0.64; p< 0.0001); 4) between Apgar score at 1 min and HyPL in CB(r= -0.53, p< 0.0001); 5) between IFIC and birth weight both at birth (r =-0.45, p< 0.0001) and on 4th day of life (r = -0.51, p < 0.0001). In conclusion, the red cells of premature infants and newborns with severe asphyxia are under oxidative stress and therefore at risk for increased hemolysis during the early neonatal period.