Quantitative immunofluorescence microscopy of subcellular GLUT4 distribution in human skeletal muscle: effects of endurance and sprint interval training

Research output: Contribution to journalArticlepeer-review

Authors

  • Chris Shaw
  • Philip Worthington
  • Sam Shepherd
  • Matt Cocks
  • Anton Wagenmakers

Colleges, School and Institutes

External organisations

  • Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Australia
  • Computational Biology, Discovery Sciences, AstraZeneca, Alderley Park, Macclesfield, UK
  • Liverpool John Moores University

Abstract

Increases in insulin‐mediated glucose uptake following endurance training (ET) and sprint interval training (SIT) have in part been attributed to concomitant increases in glucose transporter 4 (GLUT4) protein content in skeletal muscle. This study used an immunofluorescence microscopy method to investigate changes in subcellular GLUT4 distribution and content following ET and SIT. Percutaneous muscle biopsy samples were taken from the m. vastus lateralis of 16 sedentary males in the overnight fasted state before and after 6 weeks of ET and SIT. An antibody was fully validated and used to show large (> 1 μm) and smaller (<1 μm) GLUT4‐containing clusters. The large clusters likely represent trans‐Golgi network stores and the smaller clusters endosomal stores and GLUT4 storage vesicles (GSVs). Density of GLUT4 clusters was higher at the fibre periphery especially in perinuclear regions. A less dense punctate distribution was seen in the rest of the muscle fibre. Total GLUT4 fluorescence intensity increased in type I and type II fibres following both ET and SIT. Large GLUT4 clusters increased in number and size in both type I and type II fibres, while the smaller clusters increased in size. The greatest increases in GLUT4 fluorescence intensity occurred within the 1 μm layer immediately adjacent to the PM. The increase in peripheral localisation and protein content of GLUT4 following ET and SIT is likely to contribute to the improvements in glucose homeostasis observed after both training modes.

Details

Original languageEnglish
Article numbere12085
JournalPhysiological reports
Volume2
Publication statusPublished - 22 Jul 2014

Keywords

  • Glucose uptake, insulin sensitivity, Skeletal muscle