Decreased insulin action on muscle glucose transport after eccentric contractions in rats.
We have recently shown that eccentric contractions (Ecc) of rat calf muscles cause muscle damage and decreased glycogen and glucose transporter GLUT-4 protein content in the white (WG) and red gastrocnemius (RG) but not in the soleus (S) (S. Asp, S. Kristiansen, and E. A. Richter. J. Appl. Physiol. 79: 1338-1345, 1995). To study whether these changes affect insulin action, hindlimbs were perfused at three different insulin concentrations (0, 200, and 20,000 microU/ml) 2 days after one-legged eccentric contractions of the calf muscles. Compared with control, basal glucose transport was slightly higher (P < 0.05) in Ecc-WG and -RG, whereas it was lower (P < 0.05) at both submaximal and maximal insulin concentrations in the Ecc-WG and at maximal concentrations in the Ecc-RG. In the Ecc-S, the glucose transport was unchanged in hindquarters perfused in the absence or presence of a submaximal stimulating concentration of insulin, whereas it was slightly (P < 0.05) higher during maximal insulin stimulation compared with control S. At the end of perfusion the glycogen concentrations were lower in both Ecc-gastrocnemius muscles compared with control muscles at all insulin concentrations. Fractional velocity of glycogen synthase increased similarly with increasing insulin concentrations in Ecc- and control WG and RG. We conclude that insulin action on glucose transport but not glycogen synthase activity is impaired in perfused muscle exposed to prior eccentric contractions.
Asp
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S
Copenhagen Muscle Research Centre, August Krogh Institute, University of Copenhagen, Denmark. sasp@aki.ku.dk
Richter
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EA
D000818:Animals; D001834:Body Water / Q000502:physiology; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4; D006003:Glycogen / Q000378:metabolism; D006006:Glycogen Synthase / Q000378:metabolism; D006614:Hindlimb / Q000098:blood supply; D007333:Insulin Resistance / Q000502:physiology*; D007866:Leg / Q000502:physiology; D008297:Male; D008353:Mannitol; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D009119:Muscle Contraction / Q000502:physiology; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow / Q000502:physiology
D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495694:Slc2a4 protein, rat; D008353:Mannitol; D006003:Glycogen; D006006:Glycogen Synthase; D005947:Glucose