Effect of fiber type and nutritional state on AICAR- and contraction-stimulated glucose transport in rat muscle.
AMP-activated protein kinase (AMPK) may mediate the stimulatory effect of contraction and 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) on glucose transport in skeletal muscle. In muscles with different fiber type composition from fasted rats, AICAR increased 2-deoxyglucose transport and total AMPK activity approximately twofold in epitrochlearis (EPI), less in flexor digitorum brevis, and not at all in soleus muscles. Contraction increased both transport and AMPK activity more than AICAR did. In EPI muscles, the effects of AICAR and contractions on glucose transport were partially additive despite a lower AMPK activity with AICAR compared with contraction alone. In EPI from fed rats, glucose transport responses were smaller than what was seen in fasted rats, and AICAR did not increase transport despite an increase in AMPK activity. AICAR and contraction activated both alpha(1)- and alpha(2)-isoforms of AMPK. Expression of both isoforms varied with fiber types, and alpha(2) was highly expressed in nuclei. In conclusion, AICAR-stimulated glucose transport varies with muscle fiber type and nutritional state. AMPK is unlikely to be the sole mediator of contraction-stimulated glucose transport.
Ai
Hua
H
Copenhagen Muscle Research Centre, Department of Medical Physiology, Panum Institute, DK-2200, Copenhagen, Denmark.
Ihlemann
Jacob
J
Hellsten
Ylva
Y
Lauritzen
Hans P M M
HP
Hardie
D Grahame
DG
Galbo
Henrik
H
Ploug
Thorkil
T
D055372:AMP-Activated Protein Kinases; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003847:Deoxyglucose / Q000378:metabolism; D005215:Fasting; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D009097:Multienzyme Complexes / Q000378:metabolism; D009119:Muscle Contraction / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D009711:Nucleotides / Q000032:analysis; D009752:Nutritional Status; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012265:Ribonucleotides / Q000494:pharmacology*
D051275:Glucose Transporter Type 4; D007527:Isoenzymes; D009004:Monosaccharide Transport Proteins; D009097:Multienzyme Complexes; D009124:Muscle Proteins; D009711:Nucleotides; D012265:Ribonucleotides; C495694:Slc2a4 protein, rat; D000620:Aminoimidazole Carboxamide; D003847:Deoxyglucose; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide; D005947:Glucose