Altered energetic properties in skeletal muscle of men with well-controlled insulin-dependent (type 1) diabetes.
This study asked whether the energetic properties of muscles are changed by insulin-dependent diabetes mellitus (or type 1 diabetes), as occurs in obesity and type 2 diabetes. We used (31)P magnetic resonance spectroscopy to measure glycolytic flux, oxidative flux, and contractile cost in the ankle dorsiflexor muscles of 10 men with well-managed type 1 diabetes and 10 age- and activity-matched control subjects. Each subject performed sustained isometric muscle contractions lasting 30 and 120 s while attempting to maintain 70-75% of maximal voluntary contraction force. An altered glycolytic flux in type 1 diabetic subjects relative to control subjects was apparent from significant differences in pH in muscle at rest and at the end of the 120-s bout. Glycolytic flux during exercise began earlier and reached a higher peak rate in diabetic patients than in control subjects. A reduced oxidative capacity in the diabetic patients' muscles was evident from a significantly slower phosphocreatine recovery from a 30-s exercise bout. Our findings represent the first characterization of the energetic properties of muscle from type 1 diabetic patients. The observed changes in glycolytic and oxidative fluxes suggest a diabetes-induced shift in the metabolic profile of muscle, consistent with studies of obesity and type 2 diabetes that point to common muscle adaptations in these diseases.
Crowther
Gregory J
GJ
Department of Physiology and Biophysics, University of Washington Medical Center, Seattle 98195, USA.
Milstein
Jerrold M
JM
Jubrias
Sharon A
SA
Kushmerick
Martin J
MJ
Gronka
Rodney K
RK
Conley
Kevin E
KE
D000328:Adult; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology*; D006019:Glycolysis / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D012146:Rest / Q000502:physiology