Limitations to basal and insulin-stimulated skeletal muscle glucose uptake in the high-fat-fed rat.

Halseth AE, Bracy DP, Wasserman DH
Am J Physiol Endocrinol Metab. 2000 279 (5): E1064-71

PMID: 11052961 · DOI:10.1152/ajpendo.2000.279.5.E1064

Rats fed a high-fat diet display blunted insulin-stimulated skeletal muscle glucose uptake. It is not clear whether this is due solely to a defect in glucose transport, or if glucose delivery and phosphorylation are also impaired. To determine this, rats were fed standard chow (control rats) or a high-fat diet (HF rats) for 4 wk. Experiments were then performed on conscious rats under basal conditions or during hyperinsulinemic euglycemic clamps. Rats received primed constant infusions of 3-O-methyl-[(3)H]glucose (3-O-MG) and [1-(14)C]mannitol. Total muscle glucose concentration and the steady-state ratio of intracellular to extracellular 3-O-MG concentration [which distributes based on the transsarcolemmal glucose gradient (TSGG)] were used to calculate glucose concentrations at the inner and outer sarcolemmal surfaces ([G](im) and [G](om), respectively) in soleus. Total muscle glucose was also measured in two fast-twitch muscles. Muscle glucose uptake was markedly decreased in HF rats. In control rats, hyperinsulinemia resulted in a decrease in soleus TSGG compared with basal, due to increased [G](im). In HF rats during hyperinsulinemia, [G](im) also exceeded zero. Hyperinsulinemia also decreased muscle glucose in HF rats, implicating impaired glucose delivery. In conclusion, defects in extracellular and intracellular components of muscle glucose uptake are of major functional significance in this model of insulin resistance.

MeSH Terms (19)

3-O-Methylglucose Animals Arteries Biological Transport Blood Glucose Body Water Carbon Radioisotopes Dietary Fats Fatty Acids, Nonesterified Glucose Hyperinsulinism Insulin Male Mannitol Muscle, Skeletal Phosphorylation Rats Rats, Sprague-Dawley Tritium

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