Activity of NADH- and NADPH-dependent methemoglobin reductases in erythrocytes from fetal to adult age. A parallel assessment.

The activities of NADH- and NADPH-dependent methemoglobin reductases were investigated in 22 fetuses between the 12th and 24th week of pregnancy and in eight age groups including premature and newborn babies and adults. Each blood sample was assayed simultaneously for both activities. NADH-methemoglobin reductase (MR) appears to be diminished in erythrocytes of premature and newborn babies. Infants below the 6th week of life also show significantly lower values than those observed in adults. Between 7 weeks and 6 months of life NADH-MR activity reaches values comparable to those of the adults. — NADPH activity in the erythrocytes of premature babies, newborns and infants is significantly higher than in older children and adults. Prior to the 18th week of gestation fetuses show NADH-MR levels lower than the older ones. NADH-MR values in fetuses between the 18th and 24th week of gestation are not different from those measured in premature babies. The NADPH-MR activity also appears to be significantly lower in fetuses of less than 19 weeks of intrauterine life in comparison with the older ones. Moreover, NADPH-MR activity in fetuses between the 19th and 24th week is lower than in prematures and newborns.