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Red cell metabolic alterations in postnatal life in term infants: glycolytic enzymes and glucose-6-phosphate
Insights
Red blood cell enzyme activity changes in infants show specific patterns in the first year. Key enzymes like phosphofructokinase (PFK) normalize, while others suggest a persistently young red cell population.
Area of Science:
- Biochemistry
- Hematology
- Pediatric Metabolism
Background:
- Red blood cell (RBC) enzyme activity is crucial for cellular function and survival.
- Understanding age-related changes in neonatal RBC enzyme profiles is vital for assessing infant health.
- Specific enzymes like enolase (ENO), phosphoglycerate kinase (PGK), and phosphofructokinase (PFK) play key roles in glycolysis.
Purpose of the Study:
- To sequentially analyze the activity of critical RBC enzymes in term infants from birth to one year.
- To identify age-dependent alterations in enzyme levels and their implications for RBC populations.
- To compare enzyme activities with mean cell age to understand neonatal hematological development.
Main Methods:
- Sequential measurement of red cell enzyme activities including ENO, PGK, PFK, G-6-PD, HK, ALD, and PK.
- Study cohort comprised term infants followed from birth up to 12 months of age.
- Enzyme activities were correlated with mean red cell age to interpret developmental trends.
Main Results:
- At birth, elevated PGK and ENO, with decreased PFK, were observed; these normalized progressively through the first year.
- Enzymes G-6-PD, PK, ALD, and HK were elevated at birth, decreasing initially then showing a secondary rise.
- Persistent elevations in G-6-PD, PK, ALD, and HK at 12 months suggest a younger-than-expected RBC population.
Conclusions:
- Neonatal RBCs exhibit distinct enzyme activity profiles that shift significantly during the first year of life.
- Changes in glycolytic enzymes (PGK, ENO, PFK) indicate a maturation process towards adult levels.
- Sustained elevated activities of certain enzymes point to the presence of a relatively young red cell population throughout infancy.
Abstract:
The activities of red cell enzymes enolase (ENO), phosphoglycerate kinase (PGK), phosphofructokinase (PFK), glucose-6-phosphate 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 full 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 11 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.