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The deleterious effects on erythrocytes of low steady-state concentrations of H2O2 in vitro have been compared in samples from full-term and premature infants and adults. Methemoglobin and Heinz bodies were formed to a greater degree in the intact erythrocytes of the young subjects. In the absence of protective enzymes, however, the extent of oxidation was similar in hemoglobin prepared from cord blood and from adult blood, respectively. Activity of the enzymes involved in the detoxification of H2O2 has been measured in the red blood cells of the aforementioned groups of subjects. Of note was the finding of significantly decreased activity of glutathione peroxidase in the full-term newborn and premature infants. These findings of increased toxicity from H2O2 and decreased efficiency of the detoxification mechanisms are considered to have bearing on the susceptibility of young subjects to drug-induced hemolytic anemia.

In recent years investigations of erythrocyte metabolism have been concerned with the interrelationships of enzymes, coenzymes, substrates, cofactors, and pH, inter alia (1-8). Although data have accumulated on these various aspects of the metabolism of normal and pathological erythrocytes, little direct information has been available heretofore on pyridine nucleotide coenzymes, despite their importance in both the glycolytic and the hexose monophosphate shunt pathways. The availability of these compounds in the blood of immature subjects is of particular interest because of certain abnormalities in the erythrocytes of fullterm newborn and prematurely born infants. These abnormalities, which include decreased survival of 51Cr-labeled erythrocytes in premature infants (9, 10) and increased susceptibility to Heinz body formation (11) and to methemoglobinemia (12-15) in both full-term and premature infants, as well as the occurrence of unexplained hemolytic anemias, suggest the possibility of transient biochemical defects in the erythrocytes of these young subjects. Although the activities of the pyridine nucleotide-dependent enzymes in both the glycolytic and shunt pathways are increased in the erythrocytes of young infants (16,17), the levels of the oxidized and reduced coenzymes themselves have not been reported.In the present study the concentrations of DPN,l

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