title: Skeletal muscle GLUT4 protein concentration and aging in humans.
abstract: The insulin resistance of aging has been attributed to a postreceptor defect in skeletal muscle. The present study examined whether a reduction in the concentration of the insulin-stimulated glucose transporter (GLUT4) in skeletal muscle was associated with advancing age in men (n = 55) and women (n = 29). Insulin sensitivity (minimal model) was negatively associated (P < 0.001) with age (range, 18-80 years) in men (r = -0.44) and women (r = -0.58). GLUT4 protein concentration in the vastus lateralis was also negatively associated (P < 0.05) with age (men, r = -0.28; women, r = -0.51). There was no relation (P > 0.15) between GLUT4 content in the gastrocnemius and age. GLUT4 concentration in the vastus lateralis was positively associated (P < 0.01) with insulin sensitivity in both sexes (r = 0.42); this relationship persisted in the men after adjusting for overall adiposity, regional adiposity, and cardiorespiratory fitness. These findings suggest that a decrement in GLUT4 protein concentration in skeletal muscle may at least partially contribute to the insulin resistance of aging in humans.
authors.affiliation: Human Performance Laboratory, School of Health and Human Performance, East Carolina University, Greenville, NC 27858, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Houmard
authors.forename: M D
authors.initials: MD
authors.lastname: Weidner
authors.forename: P L
authors.initials: PL
authors.lastname: Dolan
authors.forename: N
authors.initials: N
authors.lastname: Leggett-Frazier
authors.forename: K E
authors.initials: KE
authors.lastname: Gavigan
authors.forename: M S
authors.initials: MS
authors.lastname: Hickey
authors.forename: G L
authors.initials: GL
authors.lastname: Tyndall
authors.forename: D
authors.initials: D
authors.lastname: Zheng
authors.forename: A
authors.initials: A
authors.lastname: Alshami
authors.forename: G L
authors.initials: GL
authors.lastname: Dohm
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D002950:Citrate (si)-Synthase / Q000378:metabolism; D005260:Female; D051275:Glucose Transporter Type 4; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000378:metabolism*; D010101:Oxygen Consumption; D010809:Physical Fitness
chemical_list: D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495692:SLC2A4 protein, human; D002950:Citrate (si)-Synthase