| Autor: |
Pencek, R. Richard, Bertoldo, Alessandra, Price, Julie, Kelley, Carol, Cobelli, Claudio, Kelley, David E. |
| Předmět: |
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| Zdroj: |
American Journal of Physiology: Endocrinology & Metabolism; Jun2006, Vol. 290, pE1124-E1130, 7p, 1 Diagram, 4 Charts, 3 Graphs |
| Abstrakt: |
Glucose transport is regarded as the principal rate control step governing insulin-stimulated glucose utilization by skeletal muscle. To assess this step in human skeletal muscle, quantitative PET imaging of skeletal muscle was performed using 3-O-methyl-[11C]glucose (3-[11C]OMG) in healthy volunteers during a two-step insulin infusion [n = 8; 30 and 120 mU·min-1·m-2, low (LO) and high (HI)] and during basal conditions (n = 8). Positron emission tomography images were coregistered with MRI to assess 3-[11C]OMG activity in regions of interest placed on oxidative (soleus) compared with glycolytic (tibialis anterior) muscle. Insulin dose-responsive increases of 3-[11C]OMG activity in muscle were observed (P < 0.01). Tissue activity was greater in soleus than in tibialis anterior (P < 0.05). Spectral analysis identified that two mathematical components interacted to shape tissue activity curves. These two components were interpreted physiologically as likely representing the kinetics of 3-[11C]OMG delivery from plasma to tissue and the kinetics of bidirectional glucose transport. During low compared with basal, there was a sixfold increase in k3, the rate constant attributed to inward glucose transport, and another threefold increase during HI (0.012 ± 0.003, 0.070 ± 0.014, 0.272 ± 0.059 min-1, P < 0.001). Values for k3 were similar in soleus and tibialis anterior, suggesting similar kinetics for transport, but compartmental modeling indicated a higher value in soleus for k1, denoting higher rates of 3-[11C]OMG delivery to soleus than to tibialis anterior. In summary, in healthy volunteers there is robust dose-responsive insulin stimulation of glucose transport in skeletal muscle. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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