Effect of tension on contraction-induced glucose transport in rat skeletal muscle.
We questioned the general view that contraction-induced muscle glucose transport only depends on stimulation frequency and not on workload. Incubated soleus muscles were electrically stimulated at a given pattern for 5 min. Resting length was adjusted to achieve either no force (0% P), maximum force (100% P), or 50% of maximum force (50% P). Glucose transport (2-deoxy-D-glucose uptake) increased directly with force development (P < 0.05) [27 +/- 2 (basal), 45 +/- 2 (0% P), 68 +/- 3 (50% P), and 94 +/- 3 (100% P) nmol. g(-1). 5 min(-1)]. Glycogen decreased at 0% P but did not change further with force development (P > 0.05). Lactate, AMP, and IMP concentrations were higher (P < 0.05) and ATP concentrations lower (P < 0.05) when force was produced than when it was not. 5'-AMP-activated protein kinase (AMPK) activity increased directly with force [20 +/- 2 (basal), 60 +/- 11 (0% P), 91 +/- 12 (50% P), and 109 +/- 12 (100% P) pmol. mg(-1). min(-1)]. Passive stretch (approximately 86% P) doubled glucose transport without altering metabolism. In conclusion, contraction-induced muscle glucose transport varies directly with force development and is not solely determined by stimulation frequency. AMPK activity is probably an essential determinant of contraction-induced glucose transport. In contrast, glycogen concentrations per se do not play a major role. Finally, passive stretch per se increases glucose transport in muscle.
Ihlemann
J
J
Copenhagen Muscle Research Center, Rigshospitalet, and Department of Medical Physiology, The Panum Institute, University of Copenhagen, 2200 Copenhagen N, Denmark. jihlemann@mfi.ku.dk
Ploug
T
T
Hellsten
Y
Y
Galbo
H
H
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003847:Deoxyglucose / Q000493:pharmacokinetics; D004558:Electric Stimulation; D005947:Glucose / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D019344:Lactic Acid; D000255:Adenosine Triphosphate; D006003:Glycogen; D003847:Deoxyglucose; D017868:Cyclic AMP-Dependent Protein Kinases; D005947:Glucose