This study assessed the effects of inactivity on GLUT-4 content of human skeletal muscle and evaluated resistance training as a countermeasure to inactivity-related changes in GLUT-4 content in skeletal muscle. Nine young men participated in the study. For 19 days, four control subjects remained in a -6 degrees head-down tilt at all times throughout bed rest, except for showering every other da...

The rates of muscle glucose uptake of trained (TR) and untrained (UT) obese Zucker rats were assessed by hindlimb perfusion under basal conditions (no insulin) in the presence of a maximally stimulating concentration of insulin (10 mU/ml) and after muscle contraction elicited by electrical stimulation of the sciatic nerve. Perfusate contained 28 mM glucose and 7.5 microCi/mmol of 2-deoxy-D-[3H]...

Endurance exercise training induces a rapid increase in the GLUT-4 isoform of the glucose transporter in muscle. In fasted rats, insulin-stimulated muscle glucose transport is increased in proportion to the increase in GLUT-4. There is evidence that high muscle glycogen may decrease insulin-stimulated glucose transport. This study was undertaken to determine whether glycogen supercompensation i...

Skeletal muscle GLUT-4 transcription in response to treatment with 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR), a known activator of AMP-activated protein kinase (AMPK), was studied in rats and mice. The increase in GLUT-4 mRNA levels in response to a single subcutaneous injection of AICAR, peaked at 13 h in white and red quadriceps muscles but not in the soleus muscle. The m...

Human peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) is a key coactivator in the regulation of gene transcriptional activity in normal tissues. However, it is not clear whether it is involved in the angiogenesis and metabolism of multiple myeloma (MM). The aim of the present study was to investigate the role of PGC-1α in MM. Small interfering RNA (siRNA) was used to inhibi...

We have established a simple procedure for the separation of intracellular pool(s) of glucose transporter isoform GLUT-4-containing vesicles from the surface sarcolemma and T tubule membranes of rat skeletal myocytes. This procedure enabled us to immunopurify intracellular GLUT-4-containing vesicles and to demonstrate that 20-30% of the receptors for insulin-like growth factor II/mannose 6-phos...

Insulin increases glucose uptake through the translocation of GLUT-4 via a pathway mediated by phosphatidylinositol 3-kinase (PI3K). In contrast, myocardial glucose uptake during ischemia and hypoxia is stimulated by the translocation of GLUT-4 to the surface of cardiac myocytes through a PI3K-independent pathway that has not been characterized. AMP-activated protein kinase (AMPK) activity is a...

Glucose and fatty acid metabolism was assessed in isolated working hearts from control C57BL/KsJ-m+/+db mice and transgenic mice overexpressing the human GLUT-4 glucose transporter (db/+-hGLUT-4). Heart rate, coronary flow, cardiac output, and cardiac power did not differ between control hearts and hearts overexpressing GLUT-4. Hearts overexpressing GLUT-4 had significantly higher rates of gluc...

This investigation examined the effects of short-term exercise training on insulin-stimulated GLUT-4 glucose transporter translocation and glucose transport activity in rat adipose cells. Male Wistar rats were randomly assigned to a sedentary (Sed) or swim training group (Sw, 4 days; final 3 days: 2 x 3 h/day). Adipose cell size decreased significantly but minimally (approximately 20%), whereas...