title: Role of the nitric oxide pathway in AMPK-mediated glucose uptake and GLUT4 translocation in heart muscle.
abstract: AMP-activated protein kinase (AMPK) is a serine-threonine kinase that regulates cellular metabolism and has an essential role in activating glucose transport during hypoxia and ischemia. The mechanisms responsible for AMPK stimulation of glucose transport are uncertain, but may involve interaction with other signaling pathways or direct effects on GLUT vesicular trafficking. One potential downstream mediator of AMPK signaling is the nitric oxide pathway. The aim of this study was to examine the extent to which AMPK mediates glucose transport through activation of the nitric oxide (NO)-signaling pathway in isolated heart muscles. Incubation with 1 mM 5-amino-4-imidazole-1-beta-carboxamide ribofuranoside (AICAR) activated AMPK (P < 0.01) and stimulated glucose uptake (P < 0.05) and translocation of the cardiomyocyte glucose transporter GLUT4 to the cell surface (P < 0.05). AICAR treatment increased phosphorylation of endothelial NO synthase (eNOS) approximately 1.8-fold (P < 0.05). eNOS, but not neuronal NOS, coimmunoprecipitated with both the alpha(2) and alpha(1) AMPK catalytic subunits in heart muscle. NO donors also increased glucose uptake and GLUT4 translocation (P < 0.05). Inhibition of NOS with N(omega)-nitro-l-arginine and N(omega)-methyl-l-arginine reduced AICAR-stimulated glucose uptake by 21 +/- 3% (P < 0.05) and 25 +/- 4% (P < 0.05), respectively. Inhibition of guanylate cyclase with ODQ and LY-83583 reduced AICAR-stimulated glucose uptake by 31 +/- 4% (P < 0.05) and 22 +/- 3% (P < 0.05), respectively, as well as GLUT4 translocation to the cell surface (P < 0.05). Taken together, these results indicate that activation of the NO-guanylate cyclase pathway contributes to, but is not the sole mediator of, AMPK stimulation of glucose uptake and GLUT4 translocation in heart muscle.
authors.affiliation: Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Ji
authors.initials: J
authors.lastname: Li
authors.forename: Xiaoyue
authors.initials: X
authors.lastname: Hu
authors.forename: Pradeepa
authors.initials: P
authors.lastname: Selvakumar
authors.forename: Raymond R
authors.initials: RR
authors.lastname: Russell
authors.forename: Samuel W
authors.initials: SW
authors.lastname: Cushman
authors.forename: Geoffrey D
authors.initials: GD
authors.lastname: Holman
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Young
mesh_terms: D055372:AMP-Activated Protein Kinases; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D004789:Enzyme Activation; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4; D007004:Hypoglycemic Agents / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000187:drug effects / Q000378:metabolism*; D009124:Muscle Proteins / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D010210:Papillary Muscles / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012265:Ribonucleotides / Q000494:pharmacology
chemical_list: D051275:Glucose Transporter Type 4; D007004:Hypoglycemic Agents; D009004:Monosaccharide Transport Proteins; D009097:Multienzyme Complexes; D009124:Muscle Proteins; D012265:Ribonucleotides; C495694:Slc2a4 protein, rat; D009569:Nitric Oxide; D000620:Aminoimidazole Carboxamide; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide; D005947:Glucose