Insulin-nonspecific reduction in skeletal muscle glucose transport in high-fat-fed rats.
High-fat feeding diminishes insulin-stimulated glucose transport in skeletal muscle. However, conflicting results are reported regarding whether phosphatidylinositol (PI)-3 kinase-independent glucose transport is also impaired in insulin-resistant high-fat-fed rodents. The aim of the present study was to study whether non-insulin-dependent mechanisms for stimulation of glucose transport are defective in skeletal muscle from high-fat-fed rats. Rats were fed normal chow diet or high-fat diet for 4 weeks and isolated epitrochlearis muscles were used for measuring glucose transport. Insulin-stimulated glucose transport was significantly lower in rats fed the high-fat diet compared with chow-fed rats (P < .05). Hypoxia-stimulated glucose transport was also reduced in high-fat-fed rats (P < .05). Nevertheless, hypoxia-stimulated adenosine monophosphate-activated protein kinase (AMPK) phosphorylation (Thr172) level was not affected by high-fat feeding. Glucose transport by sodium nitroprusside stimulation was reduced in high-fat-fed rats (P < .05). Protein content of glucose transporter (GLUT)-4 and AMPK-alpha, and glycogen content were comparable between both groups. Our findings provide evidence that high-fat feeding can affect not only insulin but also non-insulin-stimulated glucose transport. A putative defect in common steps in glucose transport may play a role to account for impaired insulin-stimulated glucose transport in rats fed a high-fat diet.
Koshinaka
K
K
Department of Sports Medicine, Graduate School of Medicine, Nagoya University, Nagoya, Japan.
Oshida
Y
Y
Han
Y-Q
YQ
Kubota
M
M
Viana
A Y I
AY
Nagasaki
M
M
Sato
Y
Y
D000263:Adenylate Kinase / Q000378:metabolism; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D015153:Blotting, Western; D004041:Dietary Fats / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012265:Ribonucleotides / Q000494:pharmacology
D004041:Dietary Fats; D051275:Glucose Transporter Type 4; D007004:Hypoglycemic Agents; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D020030:Nitric Oxide Donors; D012265:Ribonucleotides; C495694:Slc2a4 protein, rat; D009599:Nitroprusside; D000620:Aminoimidazole Carboxamide; D019869:Phosphatidylinositol 3-Kinases; D000263:Adenylate Kinase; C031143:AICA ribonucleotide; D005947:Glucose