title: Developmental changes in erythrocyte Na(+),K(+)-ATPase subunit abundance and enzyme activity in neonates.
abstract: OBJECTIVE
  To study the relation between erythrocyte Na(+),K(+)-ATPase subunit isoform composition, Na(+),K(+)-ATPase activity, and cation pump function in preterm and term neonates.
  
  
  METHODS
  Erythrocyte Na(+),K(+)-ATPase subunit isoform abundance, Na(+),K(+)-ATPase activity, and cation pump function were studied in blood samples obtained from 56 preterm neonates of 28-32 weeks gestation (group 1), 58 preterm neonates of 33-36 weeks gestation (group 2), and 122 term neonates (group 3) during the first two postnatal days.
  
  
  RESULTS
  alpha(1) isoform abundance was higher and beta(2) isoform abundance was lower in group 1 than in group 3 (p = 0.0002). alpha(2) and beta(1) isoform abundance did not change with maturation and there was no evidence for the presence of the alpha(3) isoform. Gestational age was inversely related to Na(+), K(+)-ATPase activity (p = 0.0001) and directly related to intracellular Na(+) concentration (p = 0.0025).
  
  
  CONCLUSIONS
  Expression of the alpha(1) and beta(2) Na(+),K(+)-ATPase subunit isoforms is developmentally regulated. The increased abundance of alpha(1) isoforms of immature neonates translates to increased ATPase activity. The lower intracellular Na(+) concentration of immature neonates suggests that their erythrocyte Na(+),K(+)-ATPase cation pump function may also be increased.
authors.affiliation: Joint Research Program of the Hungarian Academy of Sciences and the 1st Department of Pediatrics, Semmelweis University School of Medicine, Budapest, Hungary.
authors.forename: B
authors.initials: B
authors.lastname: Vasarhelyi
authors.forename: T
authors.initials: T
authors.lastname: Tulassay
authors.forename: A
authors.initials: A
authors.lastname: Ver
authors.forename: M
authors.initials: M
authors.lastname: Dobos
authors.forename: I
authors.initials: I
authors.lastname: Kocsis
authors.forename: I
authors.initials: I
authors.lastname: Seri
mesh_terms: D015153:Blotting, Western; D004912:Erythrocytes / Q000737:chemistry / Q000201:enzymology*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood*; D016623:Ion Pumps / Q000378:metabolism*; D007527:Isoenzymes / Q000032:analysis; D012964:Sodium / Q000032:analysis; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
chemical_list: D016623:Ion Pumps; D007527:Isoenzymes; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase