Brief dietary restriction increases skeletal muscle glucose transport in old Fischer 344 rats.
The primary purpose of this study was to determine the impact of brief dietary restriction (DR; 5 or 20 days) on skeletal muscle glucose transport activity (GTA) of 24-month-old female Fischer 344 rats. Basal GTA of isolated epitrochlearis muscles was unaffected by DR. Insulin-stimulated GTA was significantly increased by DR only at 20 days (51%). We also assessed the influence of DR on energy sources (blood-borne and stored). An approximately 20% decline in glycemia occurred in each DR group, but plasma-free fatty acid and beta-hydroxybutyrate concentrations were unaffected. Plasma insulin was reduced by 50% after 20 days. Hepatic glycogen was rapidly mobilized (-69% at 5 days; -83% at 20 days). The depletions of visceral adipose stores was slower (no significant decline at 5 days; -30% at 20 days), but the eventual reduction accounts for a significant amount of energy. The results demonstrate that muscle from old rats can rapidly upregulate GTA in response to brief DR. The relative magnitude of this increase represents a substantial portion of the increases previously observed after prolonged DR.
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Biodynamics Laboratory, University of Wisconsin, Madison, USA.
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D020155:3-Hydroxybutyric Acid; D019325:3-O-Methylglucose; D000375:Aging / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D001835:Body Weight; D004032:Diet; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism; D006885:Hydroxybutyrates / Q000097:blood; D007328:Insulin / Q000097:blood; D008112:Liver Glycogen / Q000378:metabolism; D008757:Methylglucosides / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000378:metabolism*; D009929:Organ Size; D051381:Rats; D011916:Rats, Inbred F344
D005230:Fatty Acids, Nonesterified; D006885:Hydroxybutyrates; D007328:Insulin; D008112:Liver Glycogen; D008757:Methylglucosides; D009124:Muscle Proteins; D019325:3-O-Methylglucose; D006003:Glycogen; D005947:Glucose; D020155:3-Hydroxybutyric Acid