K dependence of the Na-K pump is abnormal in erythrocytes from patients with cystic fibrosis and obligate heterozygotes.
The affinity of the Na-K pump for K was significantly (P less than .001) lower in erythrocytes from patients with cystic fibrosis (Km 4.6 +/- 0.35 mM; n = 26) or from heterozygotes (Km 3.9 +/- 0.57 mM; n = 12) than in controls (Km 2.2 +/- 0.10 mM; n = 20). The affinity of the Na-K pump for K was lower in normal erythrocytes than in normal fibroblasts which may explain the variability in the severity of involvement of different organs in cystic fibrosis. We have now shown in human skin fibroblasts and erythrocytes, that the K affinity of the Na-K pump is lower in patients with cystic fibrosis than in controls. Since the abnormality is also present in erythrocytes from heterozygotes who are clinically normal, it is likely that this abnormality is closely related to the genetic defect in cystic fibrosis.
D003550:Cystic Fibrosis / Q000201:enzymology*; D004912:Erythrocytes / Q000201:enzymology; D006579:Heterozygote; D006801:Humans; D007700:Kinetics; D011188:Potassium / Q000378:metabolism*; D012867:Skin / Q000201:enzymology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium