title: Contraction-induced skeletal muscle FAT/CD36 trafficking and FA uptake is AMPK independent.
abstract: The aim of this study was to investigate the molecular mechanisms regulating FA translocase CD36 (FAT/CD36) translocation and FA uptake in skeletal muscle during contractions. In one model, wild-type (WT) and AMP-dependent protein kinase kinase dead (AMPK KD) mice were exercised or extensor digitorum longus (EDL) and soleus (SOL) muscles were contracted, ex vivo. In separate studies, FAT/CD36 translocation and FA uptake in response to muscle contractions were investigated in the perfused rat hindlimb. Exercise induced a similar increase in skeletal muscle cell surface membrane FAT/CD36 content in WT (+34%) and AMPK KD (+37%) mice. In contrast, 5-aminoimidazole-4-carboxamide ribonucleoside only induced an increase in cell surface FAT/CD36 content in WT (+29%) mice. Furthermore, in the perfused rat hindlimb, muscle contraction induced a rapid (1 min, +15%) and sustained (10 min, +24%) FAT/CD36 relocation to cell surface membranes. The increase in cell surface FAT/CD36 protein content with muscle contractions was associated with increased FA uptake, both in EDL and SOL muscle from WT and AMPK KD mice and in the perfused rat hindlimb. This suggests that AMPK is not essential in regulation of FAT/CD36 translocation and FA uptake in skeletal muscle during contractions. However, AMPK could be important in regulation of FAT/CD36 distribution in other physiological situations.
authors.affiliation: Copenhagen Muscle Research Center, Molecular Physiology Group, Section of Human Physiology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Jeppesen
authors.forename: P H
authors.initials: PH
authors.lastname: Albers
authors.forename: A J
authors.initials: AJ
authors.lastname: Rose
authors.forename: J B
authors.initials: JB
authors.lastname: Birk
authors.forename: P
authors.initials: P
authors.lastname: Schjerling
authors.forename: N
authors.initials: N
authors.lastname: Dzamko
authors.forename: G R
authors.initials: GR
authors.lastname: Steinberg
authors.forename: B
authors.initials: B
authors.lastname: Kiens
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects* / Q000235:genetics; D018955:CD36 Antigens / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D010805:Physical Conditioning, Animal / Q000502:physiology; D021381:Protein Transport; D051381:Rats; D012263:Ribonucleosides / Q000494:pharmacology
chemical_list: D018955:CD36 Antigens; D005227:Fatty Acids; D012263:Ribonucleosides; D000620:Aminoimidazole Carboxamide; C011651:acadesine; D055372:AMP-Activated Protein Kinases