| المؤلفون: |
Blackwood SJ; Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Sweden., Tischer D; The Swedish School of Sport and Health Sciences, Sweden., van de Ven MPF; The Swedish School of Sport and Health Sciences, Sweden., Pontén M; Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Sweden., Edman S; Karolinska Institutet, Sweden., Horwath O; Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden., Apró W; Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences; Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden., Röja J; The Swedish School of Sport and Health Sciences, Sweden., Ekblom MM; Department of Physical Activity and Health, The Swedish School of Sport and Health Sciences; Department of Neuroscience, Karolinska Institutet, Älta, Sweden., Moberg M; Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden., Katz A; Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden. |
| مستخلص: |
Insulin resistance (IR) is a risk factor for the development of several major metabolic diseases. Muscle fiber composition is established early in life and is associated with insulin sensitivity. Hence, muscle fiber composition was used to identify early defects in the development of IR in healthy young individuals in the absence of clinical manifestations. Biopsies were obtained from the thigh muscle, followed by an intravenous glucose tolerance test. Indices of insulin action were calculated and cardiovascular measurements, analyses of blood and muscle were performed. Whole-body insulin sensitivity (SI galvin ) was positively related to expression of type I muscle fibers (r=0.49; P<0.001) and negatively related to resting heart rate (HR, r=-0.39; P<0.001), which was also negatively related to expression of type I muscle fibers (r=-0.41; P<0.001). Muscle protein expression of endothelial nitric oxide synthase (eNOS), whose activation results in vasodilation, was measured in two subsets of subjects expressing a high percentage of type I fibers (59±6%; HR = 57±9 beats/min; SI galvin = 1.8±0.7 units) or low percentage of type I fibers (30±6%; HR = 71±11; SI galvin = 0.8±0.3 units; P<0.001 for all variables vs. first group). eNOS expression was: 1. higher in subjects with high type I expression; 2. almost two-fold higher in pools of type I vs. II fibers; 3. only detected in capillaries surrounding muscle fibers; and 4. linearly associated with SI galvin . These data demonstrate that an altered function of the autonomic nervous system and a compromised capacity for vasodilation in the microvasculature occur early in the development of IR. |
