Oxidative challenge and glucose-6-phosphate dehydrogenase activity of preterm and term neonatal red blood cells.

BACKGROUND

Recent studies suggest that a low antioxidant level in preterm infants may predispose them to increased oxidative stress and results in hyperbilirubinemia, whereas glucose-6-phosphate dehydrogenase (G6PD) activity was found to be higher in preterm infants than in term infants.

OBJECTIVES

To evaluate (1) the oxidative effect of alpha-naphthol on preterm and term red blood cells, and (2) the relationship between G6PD activity and the gestational age of these infants.

METHODS

G6PD activities were determined in preterm and term infants by a standard diagnostic method. Whole blood samples were incubated with alpha-naphthol for 2 h and their pre- and post-challenged reduced glutathione (GSH) levels were quantified.

RESULTS

The mean G6PD activity in preterm infants (n = 113; 13.52 +/- 0.19 U/g Hb; gestational age 30.67 +/- 0.28 weeks) was significantly higher than that in term infants (n = 100; 12.36 +/- 0.16 U/g Hb; gestational age 39.82 +/- 0.14 weeks; p < 0.001). A significantly negative correlation was demonstrated between gestational age and G6PD activity (r = -0.34, p < 0.001). GSH levels of preterm and term subjects were similar at baseline, but were significantly decreased upon challenge with alpha-naphthol (p < 0.001). The percentage reduction in GSH levels was similar in the various gestational age groups.

CONCLUSIONS

Our data show that G6PD activities had a negative correlation with gestational age of G6PD-normal infants. The similar response of preterm and term erythrocytes to an alpha-naphthol challenge indicates the manifestation of an active anti-oxidative pathway mediated by cellular GSH.