title: Persistent effects of exercise on skeletal muscle glucose transport across the life-span of rats.
abstract: Very young rats (< 2 mo) have a persistent increase in insulin-stimulated glucose transport rate in skeletal muscle for several hours after completing a bout of exercise. We studied the effect of exercise on the glucose transport activity of isolated epitrochlearis muscles from male Fischer 344/Brown Norway F1 hybrid rats across a wide range of the life-span (at 3.5, 13, and 25 mo). The stimulation of 3-O-methylglucose (3-MG) accumulation by a submaximally effective insulin concentration (100 microU/ml) was enhanced (50-75%) 4 h after exercise, regardless of age. In contrast, the 3-MG transport rate with 20,000 microU/ml insulin was enhanced after exercise only in the youngest rats (35%), and this increased responsiveness occurred despite no changes in muscle total GLUT-4 levels. In addition, epitrochlearis GLUT-4 levels were reduced by 29% between 3.5 and 13 mo of age in sedentary rats but did not decline further between 13 and 25 mo of age. GLUT-4 levels were moderately but significantly (P < 0.05) related (r = 0.554) to epitrochlearis muscle capacity for insulin-stimulated 3-MG transport.
authors.affiliation: Biodynamics Laboratory, University of Wisconsin, Madison 53706.
authors.forename: G D
authors.initials: GD
authors.lastname: Cartee
authors.forename: C
authors.initials: C
authors.lastname: Briggs-Tung
authors.forename: E W
authors.initials: EW
authors.lastname: Kietzke
mesh_terms: D019325:3-O-Methylglucose; D000375:Aging / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4; D006003:Glycogen / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology; D008297:Male; D008757:Methylglucosides / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D009124:Muscle Proteins; D009132:Muscles / Q000378:metabolism*; D005082:Physical Exertion / Q000502:physiology*; D051381:Rats; D011914:Rats, Inbred BN; D011916:Rats, Inbred F344
chemical_list: D001786:Blood Glucose; D051275:Glucose Transporter Type 4; D007328:Insulin; D008757:Methylglucosides; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495694:Slc2a4 protein, rat; D019325:3-O-Methylglucose; D006003:Glycogen; D005947:Glucose