Adaptation of muscle glucose transport with caloric restriction in adult, middle-aged, and old rats.
The effects of prolonged caloric restriction (60% of ad libitum intake initiated at 14 wk of age) on glucose transport activity in isolated epitrochlearis muscles were studied in female Fischer 344 rats aged 8, 18, and 23 mo. Basal 3-O-methylglucose transport (3-MG) rate (without insulin) was not significantly altered by caloric restriction. With a submaximally effective insulin concentration (75 microU/ml), 3-MG transport was enhanced in the caloric-restricted groups by 59, 59, and 105% at 8, 18, and 23 mo of age, respectively. With a maximally effective insulin concentration (20,000 microU/ml), 3-MG transport was increased after caloric restriction, despite no change in muscle GLUT4 glucose transporter protein content. These results indicate that chronic caloric restriction enhances insulin stimulation of the glucose transport system independent of changes in basal glucose transport or muscle GLUT4 levels, and insulin-stimulated glucose transport is enhanced in rats with chronic caloric restriction at least until 23 mo of age.
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Biodynamics Laboratory, University of Wisconsin-Madison 53706.
Kietzke
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Briggs-Tung
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D019325:3-O-Methylglucose; D000375:Aging / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D004038:Diet, Reducing; D002149:Energy Intake; D005260:Female; D051275:Glucose Transporter Type 4; D008757:Methylglucosides / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D024510:Muscle Development; D009124:Muscle Proteins; D009132:Muscles / Q000378:metabolism* / Q000502:physiology; D009929:Organ Size; D051381:Rats; D011916:Rats, Inbred F344; D012016:Reference Values
D001786:Blood Glucose; D051275:Glucose Transporter Type 4; D008757:Methylglucosides; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495694:Slc2a4 protein, rat; D019325:3-O-Methylglucose