Muscle sodium, potassium, and [(3)H]ouabain binding in identical twins, discordant for type 2 diabetes.
A reduced functional capacity of the sodium (Na), potassium (K) pump might reduce energy expenditure, inducing obesity and type 2 diabetes. Consequently, the Na and K content and [(3)H]ouabain binding capacity of skeletal muscle were measured in 10 monozygotic twin pairs discordant for type 2 diabetes and in 10 obese controls. Muscle [(3)H]ouabain binding capacity was reduced by approximately 20% in type 2 diabetes. Removing the genetic component by looking at differences within twin pairs, the difference in waist/hip ratio was associated with the difference in [(3)H]ouabain binding (r = -0.85; P < 0.002). Except for the type 2 diabetic twins in the basal state, both basal and insulin-stimulated energy expenditure were associated with the muscle K/Na ratio in the twins. In controls, the 2-h plasma glucose concentration during an oral glucose tolerance test was associated with the change in both muscle and plasma K induced by a euglycemic, hyperinsulinemic clamp. In conclusion, environmental factors related to the waist/hip ratio reduce the muscle [(3)H]ouabain binding capacity in type 2 diabetes. Without proving causality, the muscle K/Na ratio is associated with energy expenditure in individuals genetically predisposed to the development of type 2 diabetes.
Djurhuus
M S
MS
Department of Clinical Biochemistry and Genetics, Odense University Hospital, 5000 Odense C, Denmark. msd@dadlnet.dk
Vaag
A
A
Klitgaard
N A
NA
D000328:Adult; D000368:Aged; D001665:Binding Sites; D001786:Blood Glucose / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000378:metabolism; D015309:Glucose Clamp Technique; D006801:Humans; D006946:Hyperinsulinism; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism*; D009765:Obesity / Q000378:metabolism; D010042:Ouabain / Q000493:pharmacokinetics*; D011188:Potassium / Q000378:metabolism*; D012016:Reference Values; D012964:Sodium / Q000378:metabolism*; D014316:Tritium; D014430:Twins, Monozygotic
D001786:Blood Glucose; D014316:Tritium; D010042:Ouabain; D012964:Sodium; D005947:Glucose; D011188:Potassium