Effect of epinephrine on glucose disposal during exercise in humans: role of muscle glycogen

Watt, Matthew J. and Hargreaves, Mark 2002, Effect of epinephrine on glucose disposal during exercise in humans: role of muscle glycogen, American journal of physiology : endocrinology and metabolism, vol. 283, no. 3, pp. 578-583.

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Title Effect of epinephrine on glucose disposal during exercise in humans: role of muscle glycogen
Author(s) Watt, Matthew J.
Hargreaves, Mark
Journal name American journal of physiology : endocrinology and metabolism
Volume number 283
Issue number 3
Start page 578
End page 583
Publisher American Physiological Society
Place of publication Bethesda, Md.
Publication date 2002-09
ISSN 0193-1849
Keyword(s) glucose transport
Summary This study examined the effect of epinephrine on glucose disposal during moderate exercise when glycogenolytic flux was limited by low preexercise skeletal muscle glycogen availability. Six male subjects cycled for 40 min at 59 ± 1% peak pulmonary O2 uptake on two occasions, either without (CON) or with (EPI) epinephrine infusion starting after 20 min of exercise. On the day before each experimental trial, subjects completed fatiguing exercise and then maintained a low carbohydrate diet to lower muscle glycogen. Muscle samples were obtained after 20 and 40 min of exercise, and glucose kinetics were measured using [6,6-2H]glucose. Exercise increased plasma epinephrine above resting concentrations in both trials, and plasma epinephrine was higher (P < 0.05) during the final 20 min in EPI compared with CON. Muscle glycogen levels were low after 20 min of exercise (CON, 117 ± 25; EPI, 122 ± 20 mmol/kg dry matter), and net muscle glycogen breakdown and muscle glucose 6-phosphate levels during the subsequent 20 min of exercise were unaffected by epinephrine infusion. Plasma glucose increased with epinephrine infusion (i.e., 20-40 min), and this was due to a decrease in glucose disposal (Rd) (40 min: CON, 33.8 ± 3; EPI, 20.9 ± 4.9 µmol · kg-1 · min-1, P < 0.05), because the exercise-induced rise in glucose rate of appearance was similar in the trials. These results show that glucose Rd during exercise is reduced by elevated plasma epinephrine, even when muscle glycogen availability and utilization are low. This suggests that the effect of epinephrine does not appear to be mediated by increased glucose 6-phosphate, secondary to enhanced muscle glycogenolysis, but may be linked to a direct effect of epinephrine on sarcolemmal glucose transport.
Language eng
Field of Research 060104 Cell Metabolism
Socio Economic Objective 970106 Expanding Knowledge in the Biological Sciences
HERDC Research category C1 Refereed article in a scholarly journal
Copyright notice ©2002, American Physiological Society
Persistent URL http://hdl.handle.net/10536/DRO/DU:30001629

Document type: Journal Article
Collections: Faculty of Health
School of Health Sciences
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