title: Prior serum- and AICAR-induced AMPK activation in primary human myocytes does not lead to subsequent increase in insulin-stimulated glucose uptake.
abstract: Exposing isolated rat skeletal muscle to 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside [AICAR, a pharmacological activator of AMP-activated protein kinase (AMPK)] plus serum leads to a subsequent increase in insulin-stimulated glucose transport (Fisher JS, Gao J, Han DH, Holloszy JO, and Nolte LA. Am J Physiol Endocrinol Metab 282: E18-E23, 2002). Our goal was to determine whether preincubation of primary human skeletal muscle cells with human serum and AICAR (Serum+AICAR) would also induce a subsequent elevation in insulin-stimulated glucose uptake. Cells were preincubated for 1 h under 4 conditions: 1) without AICAR or serum (Control), 2) with serum, 3) with AICAR, or 4) with Serum+AICAR. Some cells were then collected for immunoblot analysis to assess phosphorylation of AMPK (pAMPK) and its substrate acetyl-CoA carboxylase (ACC). Other cells were incubated for an additional 4 h without AICAR or serum and then used to measure basal or insulin-stimulated 2-deoxyglucose (2-DG) uptake. Level of pAMPK was increased (P < 0.01) for myotubes exposed to Serum+AICAR vs. all other groups. Phosphorylated ACC (pACC) levels were higher for both Serum+AICAR (P < 0.05) and AICAR (P < 0.05) vs. Control and Serum groups. Basal (P < 0.05) and 1.2 nM insulin-stimulated (P < 0.005) 2-DG uptake was higher for Serum vs. all other preincubation conditions at equal insulin concentration. Regardless of insulin concentration (0, 1.2, or 18 nM), 2-DG was unaltered in cells preincubated with Serum+AICAR vs. Control cells. In contrast to results with isolated rat skeletal muscle, increasing the pAMPK and pACC in human myocytes via preincubation with Serum+AICAR was insufficient to lead to a subsequent enhancement in insulin-stimulated glucose uptake.
authors.affiliation: Department of Surgical Science, Karolinska Institute, Stockholm, Sweden.
authors.forename: Lubna
authors.initials: L
authors.lastname: Al-Khalili
authors.forename: Anna
authors.initials: A
authors.lastname: Krook
authors.forename: Juleen R
authors.initials: JR
authors.lastname: Zierath
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Cartee
mesh_terms: D055372:AMP-Activated Protein Kinases; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D001769:Blood; D003847:Deoxyglucose / Q000493:pharmacokinetics; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007328:Insulin / Q000494:pharmacology*; D009097:Multienzyme Complexes / Q000378:metabolism*; D032342:Muscle Cells / Q000201:enzymology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000201:enzymology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051381:Rats; D012265:Ribonucleotides / Q000494:pharmacology*
chemical_list: D007328:Insulin; D009097:Multienzyme Complexes; D012265:Ribonucleotides; D000620:Aminoimidazole Carboxamide; D003847:Deoxyglucose; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide; D005947:Glucose