RED CELL METABOLISM IN THE NEWBORN INFANT. V. GLYCOLYTIC INTERMEDIATES AND GLYCOLYTIC ENZYMES

Abstract

Previous studies demonstrated that the erythrocytes of the newborn infant have a relative phosphofructokinase deficiency and inappropriate glucose consumption for cell age. In view of these findings, an analysis of red cell glycolytic intermediates and all Embden-Meyerhof pathway enzyme activities was made in the red cells of infants, normal adults, and subjects with reticulocytosis to define further differences in metabolism and search for evidence of a metabolic blockade. The erythrocytes of subjects with reticulocytosis were found to possess increased quantities of glucose-6-phosphate, fructose-6-phosphate and 2,3-diphosphoglycerate. The elevation of the hexose phosphates was even greater in the red cells of the premature infants and was associated with a decrease in levels of 2,3-diphosphoglycerate and phosphoenolpyruvate. Measurement of enzyme activities indicated that, in addition to the phosphofructokinase deficiency, the cells of the newborn infant have markedly increased activities of enolase and phosphoglycerate kinase. It is suggested that the increase in the level of the hexose phosphates in the erythrocytes of the infants and subjects with reticulocytosis is a reflection of this relative phosphofructokinase deficiency, with this deficiency being greater in newborn infants. The differences in the enzymatic profile between the erythrocytes of the newborn and those of the normal adult is not solely a function of their younger age. Some of the differences are a reflection of the presence of a cell unique to this period of life.