title: Erythrocyte membrane abnormalities in human myotonic dystrophy.
abstract: Membrane-bound enzyme activities and cardiac glycoside binding were determined in red blood cell membrane preparations from patients with myotonic dystrophy and in age matched controls. Na+-K+-activated ATPase activity was significantly increased in myotonic patients. [3H]Ouabain binding to erythrocyte membranes was also significantly increased in myotonic dystrophy patients. The Mg2+-ATPase (ouabain-insensitive) was, however, unchanged. The K+-stimulated paranitrophenyl phosphatase (KPNPPase) activity was markedly enhanced in myotonic patients as compared to controls. The kinetic analysis showed a marked change in Vmax of Na+-K+ ATPase with respect to the activation by Na+, K+ and ATP. However, the Km values were the same in control as well as in myotonic groups. The increased erythrocyte membrane Na+-K+-ATPase activity, KPNPPase and [3H]ouabain binding in myotonic patients supports the hypothesis that generalized membrane abnormality may be involved in pathogenesis of the human myotonic dystrophy.
mesh_terms: D009597:4-Nitrophenylphosphatase / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000328:Adult; D004910:Erythrocyte Membrane / Q000201:enzymology / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D008274:Magnesium / Q000494:pharmacology; D008875:Middle Aged; D009136:Muscular Dystrophies / Q000097:blood* / Q000201:enzymology; D009222:Myotonia / Q000097:blood* / Q000201:enzymology; D010042:Ouabain / Q000378:metabolism; D011485:Protein Binding; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013577:Syndrome
chemical_list: D010042:Ouabain; D009597:4-Nitrophenylphosphatase; D000251:Adenosine Triphosphatases; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium