title: Glucocorticoids in metabolic control during exercise: glycogen metabolism.
abstract: In order to evaluate the participation of glucocorticoids in the control of glycogen metabolism during exercise, experiments were performed on male adrenalectomized and normal rats. In adrenalectomized rats swimming for 4 hours induced less pronounced increases in lactate concentrations in skeletal muscles than in normal rats (in FG fibers up to 10.7 +/- 1.0 vs 14.8 +/- 1.2 and in SO fibers up to 9.1 +/- 0.7 vs 12.5 +/- 0.7 mg x g-1 wet tissue). The glycogen drop in liver and oxidative muscles was also less pronounced (in liver by 14% vs 52%, in SO fibers by 33% vs 54% in normal rats). Swimming until exhaustion led to an extremely low glucose level in blood (1.89 +/- 0.12 mMol x L-1) in adrenalectomized rats. When they were treated with dexamethasone, the swimming duration was longer (12 +/- 1 hours vs 9 +/- 0.8 hours in saline treated), blood glucose level at exhaustion was higher (3.07 +/- 0.23 mMol x L-1) and the drop of hepatic and muscle glycogen was more pronounced. In normal rats hepatic glycogen content dropped by 68% after swimming for 4 hours. After swimming for 8 or 12 hours further decreases in hepatic glycogen content were insignificant. High levels of corticosterone in blood was found after swimming for 4 and 8 hours. After swimming for 16 hours corticosterone concentration was below normal and a new drop in liver glycogen (until a level constituting only 11% initial) was recorded. The results support the suggestion that glucocorticoids, regulate hepatic glycogen and peripheral glucose utilization during exercise, and also participate in the control of glycogenolysis in muscles.
authors.affiliation: Department of Exercise Biology, Tartu University, Estonia.
authors.forename: M
authors.initials: M
authors.lastname: Viru
authors.forename: L
authors.initials: L
authors.lastname: Litvinova
authors.forename: T
authors.initials: T
authors.lastname: Smirnova
authors.forename: A
authors.initials: A
authors.lastname: Viru
mesh_terms: D000311:Adrenal Glands / Q000502:physiology*; D000315:Adrenalectomy; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D003345:Corticosterone / Q000097:blood; D003907:Dexamethasone / Q000494:pharmacology; D005938:Glucocorticoids / Q000502:physiology*; D006003:Glycogen / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism; D010807:Physical Endurance; D051381:Rats; D017208:Rats, Wistar; D013550:Swimming / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D005938:Glucocorticoids; D007773:Lactates; D003907:Dexamethasone; D006003:Glycogen; D003345:Corticosterone