Erythrocyte sodium-potassium transport in hyperkalaemic and normokalaemic infants.
One of the causes of early onset hyperkalaemia in very low birth weight infants is presumed to be the dysfunction of K+ transport across the cell membrane. Sodium-potassium adenosine triphosphatase(Na(+)-K+ ATPase) is known to play a major role in K+ transport. We compared the concentrations of erythrocyte Na(+)-K+ ATPase (Vmax levels) for hyperkalaemic and normokalaemic infants of matched gestational age. In hyperkalaemic infants, the highest levels of Vmax were reached at 24-48 h after birth, but in normokalaemic infants, there were no significant changes in Vmax levels during the 1st week after birth. At 12-72 h after birth, erythrocyte K+ concentrations for hyperkalaemic infants were higher than those of normokalaemic infants. For both groups of infants, the highest levels of plasma K+ during the 1st week after birth showed a positive correlation with those of Vmax.


CONCLUSIONS
Na(+)-K+ ATPase on the cell membrane is activated to compensate for hyperkalaemia; however, when this compensation is incomplete, hyperkalaemia occurs.
Matsuo
Y
Y
Department of Paediatrics, Kyoto Prefectural University of Medicine, Japan.
Hasegawa
K
K
Doi
Y
Y
Kinugasa
A
A
Uchiyama
M
M
Sawada
T
T
D004910:Erythrocyte Membrane / Q000201:enzymology; D004912:Erythrocytes / Q000201:enzymology*; D005260:Female; D006801:Humans; D006947:Hyperkalemia / Q000201:enzymology*; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000201:enzymology*; D019102:Infant, Very Low Birth Weight / Q000097:blood; D008297:Male; D011188:Potassium / Q000097:blood; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology*
D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium