Control of fructose 2,6-diphosphate in muscle of exercising fasted rats.
This study examined the role of epinephrine in controlling intramuscular signals that may accelerate lactate production in less active muscles during exercise. Sham-operated (sham) or adrenodemedullated (ADM) rats were fasted 24 h and then were killed at rest or after running for 15 or 30 min on a treadmill (21 m/min, 15% grade). One-half of the ADM rats were infused with epinephrine (6 micrograms/h) intravenously (jugular catheter) during exercise. ADM rats exhibited lower blood glucose, blood lactate, white quadriceps muscle content of lactate, glucose 6-phosphate, fructose 6-phosphate, and adenosine 3',5'-cyclic monophosphate (cAMP) during exercise than did sham rats or epinephrine-infused ADM rats. The white quadriceps muscle contents of fructose 2,6-diphosphate (F-2,6-P2) and glucose 1,6-diphosphate (G-1,6-P2) (allosteric activators of glycolysis) were at least two times as high in sham rats and in epinephrine-infused rats as in ADM rats during exercise. We conclude that the exercise-induced rise in epinephrine is responsible for the acceleration of glycolysis in less active muscle during exercise. This effect is likely mediated by epinephrine-induced increases in cAMP, F-2,6-P2, and G-1,6-P2.
Winder
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Zoology Department, Brigham Young University, Provo, Utah 84602.
Duan
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D000313:Adrenal Medulla / Q000502:physiology*; D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D004837:Epinephrine / Q000097:blood / Q000494:pharmacology; D005215:Fasting; D005635:Fructosediphosphates / Q000378:metabolism*; D005934:Glucagon / Q000097:blood; D006003:Glycogen / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D007773:Lactates / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D009132:Muscles / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D009638:Norepinephrine / Q000097:blood; D009928:Organ Specificity; D005082:Physical Exertion; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values
D005635:Fructosediphosphates; D007328:Insulin; D007773:Lactates; C027652:fructose 2,6-diphosphate; D006003:Glycogen; D005934:Glucagon; D000242:Cyclic AMP; D009638:Norepinephrine; D004837:Epinephrine