In vivo quantification of glucose uptake and conversion to glycogen in individual muscles of the rat following exercise

• Published in: Metabolism, clinical and experimental clinical and experimental, 1998-04, Vol.47 (4), p.409-414
• Main Authors: Furler, S.M., Goldstein, M., Cooney, G.J., Kraegen, E.W.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Carbohydrates; Fundamental and applied biological sciences. Psychology; Glucose - metabolism; Glycogen - metabolism; Hindlimb; Male; Metabolisms and neurohumoral controls; Muscle, Skeletal - metabolism; Physical Exertion - physiology; Rats; Rats, Wistar; Space life sciences; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 0026-0495; 1532-8600
• DOI: 10.1016/S0026-0495(98)90051-8

Glycogen depletion is thought to be a potent stimulus for the substantially increased glucose fluxes observed in skeletal muscle following exercise. The aim of this study was to establish the relationships between the glycogen mass and the rates of glucose uptake (R′ g) and glucose incorporation into glycogen (R gly) in individual muscles of conscious adult Wistar rats following moderate nonexhausting treadmill exercise (15 m/min at a 10° slope for 45 minutes, ∼65% V̇o 2max). Muscle glycogen content was determined at 0, 20, 45, 90, or 135 minutes following exercise and compared with R′ g and R gly measurements at matched times. Muscle types varied in the rate of glycogen resynthesis. Glycogen depots of glycolytic muscle (white gastrocnemius) were still significantly ( P < .01) lower than preexercise levels after 135 minutes; red oxidative muscles (soleus and red gastrocnemius) were essentially repleted by 90 minutes. Immediately following exercise, R′ g and R gly in red gastrocnemius and soleus were 42 ± 4 and 42 ± 5 and 36 ± 2 and 33 ± 7 μmol/(min · 100 g), greater than the rates induced by maximal insulin stimulation in previous studies. In red muscles, there was a strong inverse relationship between R gly and tissue glycogen content, consistent with a dominant role for the glycogen mass in the regulation of glycogen resynthesis.