High glycogen levels enhance glycogen breakdown in isolated contracting skeletal muscle
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High glycogen levels enhance glycogen breakdown in isolated contracting skeletal muscle. / Richter, Erik A.; Galbo, H.
In: Journal of Applied Physiology, Vol. 61, No. 3, 1986, p. 827-831.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - High glycogen levels enhance glycogen breakdown in isolated contracting skeletal muscle
AU - Richter, Erik A.
AU - Galbo, H
PY - 1986
Y1 - 1986
N2 - The influence of supranormal muscle glycogen levels on glycogen breakdown in contracting muscle was investigated. Rats either rested or swam for 3 h and subsequently had their isolated hindquarters perfused after 21 h with access to food. Muscle glycogen concentrations were measured before and after 15 min of intermittent electrical muscle stimulation. Before stimulation, glycogen was higher in rats that swam on the preceding day (supercompensated rats) compared with controls. During muscle contractions, glycogen breakdown in fast-twitch red and white fibers was larger in supercompensated hindquarters than in controls, and glycogenolysis correlated significantly with precontraction glycogen concentrations. In slow-twitch fibers, electrical stimulation did not elicit glycogenolysis in either group. Glucose uptake and lactate release were decreased and increased, respectively, in supercompensated hindquarters compared with controls. O2 uptake, release of tyrosine and glycerol, and tension development were similar in the two groups. In conclusion, during muscle contractions, increased muscle glycogen levels lead to increased breakdown of glycogen and release of lactate and decreased uptake of glucose by mechanisms exerted within the muscle cells. Intramuscular lipolysis and net protein breakdown are unaffected. There seems to be no close linkage between needs and mobilization of fuel within the working muscle.
AB - The influence of supranormal muscle glycogen levels on glycogen breakdown in contracting muscle was investigated. Rats either rested or swam for 3 h and subsequently had their isolated hindquarters perfused after 21 h with access to food. Muscle glycogen concentrations were measured before and after 15 min of intermittent electrical muscle stimulation. Before stimulation, glycogen was higher in rats that swam on the preceding day (supercompensated rats) compared with controls. During muscle contractions, glycogen breakdown in fast-twitch red and white fibers was larger in supercompensated hindquarters than in controls, and glycogenolysis correlated significantly with precontraction glycogen concentrations. In slow-twitch fibers, electrical stimulation did not elicit glycogenolysis in either group. Glucose uptake and lactate release were decreased and increased, respectively, in supercompensated hindquarters compared with controls. O2 uptake, release of tyrosine and glycerol, and tension development were similar in the two groups. In conclusion, during muscle contractions, increased muscle glycogen levels lead to increased breakdown of glycogen and release of lactate and decreased uptake of glucose by mechanisms exerted within the muscle cells. Intramuscular lipolysis and net protein breakdown are unaffected. There seems to be no close linkage between needs and mobilization of fuel within the working muscle.
KW - Animals
KW - Electric Stimulation
KW - Glycogen
KW - In Vitro Techniques
KW - Lactates
KW - Lactic Acid
KW - Lipolysis
KW - Male
KW - Muscle Contraction
KW - Muscles
KW - Perfusion
KW - Rats
KW - Rats, Inbred Strains
M3 - Journal article
C2 - 3759767
VL - 61
SP - 827
EP - 831
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
SN - 8750-7587
IS - 3
ER -
ID: 154758121