Open AccessQuantitative immunofluorescence microscopy of subcellular GLUT 4 distribution in human skeletal muscle: effects of endurance and sprint interval training
Author(s) -
Bradley Helen,
Shaw Christopher S.,
Worthington Philip L.,
Shepherd Sam O.,
Cocks Matthew,
Wagenmakers Anton J. M.
Publication year - 2014
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.12085
Subject(s) - glut4 , skeletal muscle , endurance training , glucose transporter , glucose uptake , immunoelectron microscopy , medicine , endocrinology , chemistry , biology , insulin , immunohistochemistry
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 ( GLUT 4) protein content in skeletal muscle. This study used an immunofluorescence microscopy method to investigate changes in subcellular GLUT 4 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 μ m) and smaller (<1 μ m) GLUT 4‐containing clusters. The large clusters likely represent trans‐Golgi network stores and the smaller clusters endosomal stores and GLUT 4 storage vesicles ( GSV s). Density of GLUT 4 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 GLUT 4 fluorescence intensity increased in type I and type II fibres following both ET and SIT . Large GLUT 4 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 GLUT 4 fluorescence intensity occurred within the 1 μ m layer immediately adjacent to the PM . The increase in peripheral localisation and protein content of GLUT 4 following ET and SIT is likely to contribute to the improvements in glucose homeostasis observed after both training modes.