Erythrocyte sodium-potassium transport in cystic fibrosis.
Erythrocytes from 15 patients with cystic fibrosis (CF) aged 8 mo to 22 y (mean age 12.8 y) were analyzed for Na+,K(+)-ATPase activity and sodium, potassium, and ATP concentrations. Sodium concentrations and Na(+)-K+ ratio of erythrocytes were statistically significantly lower in the CF patients [6.6 (SD 1.9) versus 9.2 (SD 1.1) mmol/L (p less than 0.01) and 0.070 (SD 0.023) versus 0.104 (SD 0.016) mmol/L (p less than 0.01), respectively]. The Na+,K(+)-ATPase activity was similar compared with that of reference individuals [536 (SD 100) versus 488 (SD 92) nmol inorganic phosphate/mg protein/h]. Intraerythrocyte sodium concentration and Na(+)-K+ ratio were thus lower in relation to the recorded Na+,K(+)-ATPase activities in controls, indicating a change of the passive transmembrane movements of sodium ions in CF. There was a rise of erythrocyte sodium and Na(+)-K+ ratio despite unchanged Na+,K(+)-ATPase activity after regular infusion of a fat emulsion rich in essential fatty acids, inferring that an altered membrane composition by essential fatty acid deficiency could explain the low intracellular sodium concentration in CF.
Sigström
L
L
Department of Pediatrics and Child Psychiatry, University of Göteborg, East Hospital, Sweden.
Strandvik
B
B
D000255:Adenosine Triphosphate / Q000097:blood; D000293:Adolescent; D000328:Adult; D001693:Biological Transport, Active; D002648:Child; D002675:Child, Preschool; D003550:Cystic Fibrosis / Q000097:blood* / Q000178:diet therapy; D004912:Erythrocytes / Q000378:metabolism; D005217:Fat Emulsions, Intravenous / Q000008:administration & dosage; D005228:Fatty Acids, Essential / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011188:Potassium / Q000097:blood*; D012964:Sodium / Q000097:blood*; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood
D005217:Fat Emulsions, Intravenous; D005228:Fatty Acids, Essential; D000255:Adenosine Triphosphate; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium