Red cell metabolic alterations in postnatal life in term infants: Glycolytic enzymes and glucose-6-phosphate dehydrogenase

Abstract

The activities of red cell enzymes enolase (ENO), phosphoglyc- erate kinase (PGK), phosphofructokinase (PFK), glucose-6-phos- phate dehydrogenase (G-6-PD), hexokinase (HK), aldolase (ALD), and pyruvate kinase (PK) were followed sequentially in term infants from birth to one year of age. At birth, red cell PGK and ENO activities were disproportionately elevated when compared to both red cells with a similar mean cell age and those with a younger mean cell age; red cell PFK was significantly decreased. There was a progressive fall in PGK and ENO activities and rise in PFK levels toward normal values in the first year of life. The most significant changes in PGK, ENO, and PFK appeared to begin at 8 to 9 wk of age. ENO and PFK activities stabilized at approximately 5 to 6 months of age at values compatible with mean cell age; mean PGK levels remained mildly elevated at II to 12 months. The age-dependent enzymes G-6-PD, PK, ALD, and HK were all elevated in term newborns. G-6-PD and ALD progressively decreased in activity during the first year of life. PK and HK decreased in activity until 8 to 9 wk when there was a secondary rise in mean activity. Mean red cell G-6-PD, PK, ALD, and HK levels remained mildly to moderately elevated at 11 to 12 months of life, suggesting the persistence of a relatively young red cell population throughout the first year of life. Speculation: The developmental changes in red cell phosphoglycerate kinase, enolase, and phosphofructokinase in the first year of postnatal life are unique to the “fetal” erythrocyte and follow a pattern that appears to be independent of red blood cell age. The initial changes in red cell phosphoglycerate kinase, enolase, and phosphofructokinase towards normal adult values appear to follow resumption of active erythropoiesis by the infants' bone marrow, which suggests that the sequential changes in these enzymes represent passage from fetal to “adult” erythropoiesis. Furthermore, evaluation of enzyme data obtained in the first year of life should be related to the knowledge that a relatively young red cell population persists and the abnormalities in the activities of phosphoglycerate kinase, enolase, and phosphofructokinase are present beyond the immediate newborn period. © 1980 International Pediatric Research Foundation, Inc.