title: Visualization and quantitation of GLUT4 translocation in human skeletal muscle following glucose ingestion and exercise.
abstract: Insulin- and contraction-stimulated increases in glucose uptake into skeletal muscle occur in part as a result of the translocation of glucose transporter 4 (GLUT4) from intracellular stores to the plasma membrane (PM). This study aimed to use immunofluorescence microscopy in human skeletal muscle to quantify GLUT4 redistribution from intracellular stores to the PM in response to glucose feeding and exercise. Percutaneous muscle biopsy samples were taken from the m. vastus lateralis of ten insulin-sensitive men in the basal state and following 30 min of cycling exercise (65% VO2 max). Muscle biopsy samples were also taken from a second cohort of ten age-, BMI- and VO2 max-matched insulin-sensitive men in the basal state and 30 and 60 min following glucose feeding (75 g glucose). GLUT4 and dystrophin colocalization, measured using the Pearson's correlation coefficient, was increased following 30 min of cycling exercise (baseline r = 0.47 ± 0.01; post exercise r = 0.58 ± 0.02; P < 0.001) and 30 min after glucose ingestion (baseline r = 0.42 ± 0.02; 30 min r = 0.46 ± 0.02; P < 0.05). Large and small GLUT4 clusters were partially depleted following 30 min cycling exercise, but not 30 min after glucose feeding. This study has, for the first time, used immunofluorescence microscopy in human skeletal muscle to quantify increases in GLUT4 and dystrophin colocalization and depletion of GLUT4 from large and smaller clusters as evidence of net GLUT4 translocation to the PM.
authors.affiliation: School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK.
authors.forename: Helen
authors.initials: H
authors.lastname: Bradley
authors.affiliation: School of Exercise and Nutrition Sciences, Deakin University, Geelong, Vic., Australia.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Shaw
authors.affiliation: Computational Biology, Discovery Sciences, AstraZeneca R&D, Cambridge, UK.
authors.forename: Claus
authors.initials: C
authors.lastname: Bendtsen
authors.affiliation: Computational Biology, Discovery Sciences, AstraZeneca R&D, Alderley Park Macclesfield, UK.
authors.forename: Philip L
authors.initials: PL
authors.lastname: Worthington
authors.affiliation: Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, UK.
authors.forename: Oliver J
authors.initials: OJ
authors.lastname: Wilson
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
authors.forename: Juliette A
authors.initials: JA
authors.lastname: Strauss
authors.affiliation: School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK.
authors.forename: Gareth A
authors.initials: GA
authors.lastname: Wallis
authors.affiliation: School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK Heart of England NHS Foundation Trust, Bordesley Green East Birmingham, UK.
authors.forename: Alice M
authors.initials: AM
authors.lastname: Turner
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK a.j.wagenmakers@ljmu.ac.uk.
authors.forename: Anton J M
authors.initials: AJ
authors.lastname: Wagenmakers
keywords: Exercise; GLUT4 translocation; glucose ingestion; skeletal muscle