Alteration in activities of Na,K, ATPase, sugar transport, and insulin receptors in erythrocytes from hyperthyroid patients.
To investigate the selectivity of the reduction in Na,K, ATPase activity in erythrocytes from patients with hyperthyroidism, we have assessed cytochalasin B-sensitive galactose uptake and insulin receptors as well as Na,K, ATPase-mediated rubidium uptake in erythrocytes from 11 patients with hyperthyroidism, 5 patients after treatment and 11 normal controls. There was a significant reduction in the Vmax values for rubidium uptake and the number of insulin receptors (23% and 20% below control, respectively), whereas there was a significant increase in the Vmax and Km values for galactose uptake (49% and 30% above control) and also in the average affinity of insulin receptors. The alterations both in rubidium and galactose transport activities were reversible with effective treatment of hyperthyroidism. The magnitude of alterations in the Vmax for rubidium uptake correlated inversely (r = -0.537 P less than 0.01, n = 16) and the Vmax and Km for galactose uptake correlated positively (r = 0.597 P less than 0.02 and r = 0.553 P less than 0.05, respectively) with serum T4 level. No correlation was found between the number of insulin receptors and serum IRI or T4 levels. These results suggest that the reduction in Na,K, ATPase activity observed in erythrocytes from hyperthyroid patients is not selective to this enzyme, but rather a reflection of widespread alterations of erythrocyte cell-surface proteins.
D019325:3-O-Methylglucose; D000328:Adult; D001692:Biological Transport; D050260:Carbohydrate Metabolism; D004910:Erythrocyte Membrane / Q000032:analysis; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D005690:Galactose / Q000378:metabolism; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood*; D008297:Male; D008560:Membrane Fluidity; D008563:Membrane Lipids / Q000032:analysis; D008757:Methylglucosides / Q000097:blood; D008875:Middle Aged; D011972:Receptor, Insulin / Q000032:analysis*; D012413:Rubidium; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood*; D013963:Thyroid Hormones / Q000097:blood
D008563:Membrane Lipids; D008757:Methylglucosides; D013963:Thyroid Hormones; D019325:3-O-Methylglucose; D011972:Receptor, Insulin; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium; D005690:Galactose