Developmental changes in erythrocyte Na(+),K(+)-ATPase subunit abundance and enzyme activity in neonates.
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.
Vasarhelyi
B
B
Joint Research Program of the Hungarian Academy of Sciences and the 1st Department of Pediatrics, Semmelweis University School of Medicine, Budapest, Hungary.
Tulassay
T
T
Ver
A
A
Dobos
M
M
Kocsis
I
I
Seri
I
I
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*
D016623:Ion Pumps; D007527:Isoenzymes; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase