ADENOSINE TRIPHOSPHATE (ATP) AND RED BLOOD CELL (RBC) GLYCOLYTIC INTERMEDIATES IN PRETERM INFANTS ON THE FIRST DAY OF LIFE

Abstract

RBC glycolytic intermediates and ATP were evaluated on the first day of life in 47 appropriate for gestational age preterm infants divided into 3 groups, 28-30 wks, 31-33 wks, and 34-36 wks, and compared to prior results in term infants. Mean concentrations of glucose-6-P (G-6-P), triose P (TTP), and ATP were significantly higher than in term infants (G-6-P: 77.3±11.4 vs 53.3±8.6; TTP: 27.7±10.8 vs 19.2±6.9; ATP: 1365±220 vs 1056±144 nmoles/ml RBC, respectively), but were appropriately elevated for the young mean age of the RBC population (G-6-P: 66.5±23.1; TTP: 22.9±5.3; ATP: 1320±231). The concentration of RBC 2,3-DPG was significantly decreased when compared to term infants (4691±383 nmoles/ml RBC) and was lowest at 28-30 wks (3567±618). An increase in 3-phosphoglycerate was noted in preterm infants and was inappropriately elevated for RBC age at 28-30 wks (68.0±10.2 vs 55.5±7.5 nmoles/ml RBC in young RBC's). This pattern of glycolytic intermediates suggests a young RBC population metabolizing at increased glycolytic rate with increased flow through the phosphoglycerate kinase reaction rather than the 2,3-DPG bypass in preterm infants. In 2 infants 28-30 wks with low intracellular pH (6.866; 7.010), there was a marked decrease in 2,3-DPG (2281; 1882 nmoles/ml RBC), ATP (650; 750 nmoles/ml RBC), and all intermediates distal to the phosphofructokinase (PFK) step, indicating a crossover at PFK secondary to acidosis. These studies show normal preterm infants have RBC's that are at a metabolic disadvantage that increases with hypoxia and/or acidosis.