Sodium potassium adenosine triphosphatase activity in preterm and term infants and its possible role in sodium homeostasis during maturation

• Published in: Archives of disease in childhood. Fetal and neonatal edition Vol. 81; no. 3; pp. F184 - F187
• Main Authors: Bistritzer, T, Berkovitch, M, Rappoport, M J, Evans, S, Arieli, S, Goldberg, M, Tavori, I, Aladjem, M
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd and Royal College of Paediatrics and Child Health 01-11-1999; BMJ; BMJ Publishing Group LTD; BMJ Group
• Subjects: Adenosine triphosphatase; Age; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Babies; Biological and medical sciences; Blood; Emergency and intensive care: neonates and children. Prematurity. Sudden death; Enzymatic activity; Enzymes; Erythrocytes; Gestational Age; Homeostasis; Homeostasis - physiology; Humans; Infant, Newborn; Infant, Premature - metabolism; Infants; Intensive care medicine; Medical sciences; Na+ K+ ATPase activity; Neonates; Original; Plasma; Potassium; Premature birth; Proteins; Respiratory distress syndrome; Sodium; sodium homeostasis; Sodium-Potassium-Exchanging ATPase - blood; Sodium-Potassium-Exchanging ATPase - metabolism; Tropical medicine; Umbilical cord; Asia; Israel; Human; Regulation(control); Newborn; Enzymatic activity; Prematurity; Sodium; Enzyme; Adenosinetriphosphatase; Homeostasis; Hydrolases; Gestational age; Comparative study
• ISSN: 1359-2998; 1468-2052
• DOI: 10.1136/fn.81.3.F184

AIM To investigate sodium (NA+) potassium (K+) adenosine triphosphatase (ATPase) activity in newborn infants at different gestational ages, to elucidate the mechanism underlying poor renal sodium conservation in preterm infants. METHODS Fifty three healthy newborn infants, gestational age 30–42 weeks, were studied. Umbilical cord red blood cell Na+ K+ATPase activity, plasma renin activity, and plasma aldosterone activities were measured in all of them. Red blood cell Na+ K+ATPase activity was re-examined in eight preterm infants, one and two weeks after birth. Total and ouabain sensitive ATPase activity was measured spectrophotometrically using a method that couples ATP hydrolysis with NADH oxidation. RESULTS Red blood cell Na+ K+ATPase activity was significantly lower (p<0.01) in preterm babies with a gestational age below 35 weeks, compared with those with aged 35 weeks and above: 2.3 (0.8) and 6.7 (1.3) nmol NADH/minute/mg protein, respectively. There was no correlation between gestational age, Na+ K+ATPase, plasma renin activity and aldosterone values either in the preterm or term babies. Two weeks after birth, irrespective of gestational age, the enzyme activity of the preterm babies increased to values similar to those observed in the term neonates at birth. CONCLUSION The differences in sodium homeostasis between term and preterm babies are modulated via changes in Na+ K+ATPase activity.