title: Glucose transporters and glucose transport in skeletal muscles of 1- to 25-mo-old rats.
abstract: It is widely thought that aging results in development of insulin resistance in skeletal muscle. In this study, we examined the effects of growth and aging on the concentration of the GLUT-4 glucose transporter and on glucose transport activity in skeletal muscles of female Long-Evans rats. Relative amounts of immunoreactive GLUT-4 protein were measured in muscle homogenates of 1-, 10-, and 25-mo-old rats by immunoblotting with a polyclonal antibody directed against GLUT-4. In the epitrochlearis, plantaris, and the red and white regions of the quadriceps muscles, GLUT-4 immunoreactivity decreased by 14-33% between 1 and 10 mo of age and thereafter remained constant. In flexor digitorum brevis (FDB) and soleus muscles, GLUT-4 concentration was similar at all three ages studied. Glucose transport activity was assessed in epitrochlearis and FDB muscles by incubation with 2-deoxyglucose under the following conditions: basal, submaximal insulin, and either maximal insulin or maximal insulin combined with contractile activity. Glucose transport in the epitrochlearis muscle decreased by approximately 60% between 1 and 4 mo of age and then did not decline further between 4 and 25 mo of age. Transport activity in the FDB assessed with a maximally effective insulin concentration decreased only slightly (< 20%) between 1 and 7 mo of age. Aging, i.e., the transition from young adulthood to old age, was not associated with a decrease in glucose transport activity in either the epitrochlearis or the FDB.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
authors.forename: E A
authors.initials: EA
authors.lastname: Gulve
authors.forename: E J
authors.initials: EJ
authors.lastname: Henriksen
authors.forename: K J
authors.initials: KJ
authors.lastname: Rodnick
authors.forename: J H
authors.initials: JH
authors.lastname: Youn
authors.forename: J O
authors.initials: JO
authors.lastname: Holloszy
mesh_terms: D000375:Aging / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D003847:Deoxyglucose / Q000493:pharmacokinetics; D005260:Female; D005947:Glucose / Q000493:pharmacokinetics*; D051275:Glucose Transporter Type 4; D015151:Immunoblotting; D009004:Monosaccharide Transport Proteins / Q000378:metabolism / Q000502:physiology*; D009124:Muscle Proteins; D009132:Muscles / Q000378:metabolism / Q000502:physiology*; D051381:Rats
chemical_list: D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495694:Slc2a4 protein, rat; D003847:Deoxyglucose; D005947:Glucose