title: A novel method to measure glucose uptake and myosin heavy chain isoform expression of single fibers from rat skeletal muscle.
abstract: Skeletal muscle includes many individual fibers with diverse phenotypes. A barrier to understanding muscle glucose uptake at the cellular level has been the absence of a method to measure glucose uptake by single fibers from mammalian skeletal muscle. This study's primary objective was to develop a procedure to measure glucose uptake by single fibers from rat skeletal muscle. Rat epitrochlearis muscles were incubated ex vivo with [(3)H]-2-deoxy-d-glucose, with or without insulin or AICAR, before isolation of ~10-30 single fibers from each muscle. Fiber type (myosin heavy chain [MHC] isoform) and glucose uptake were determined for each single fiber. Insulin-stimulated glucose uptake (which was cytochalasin B inhibitable) varied according to MHC isoform expression, with ~2-fold greater values for IIA versus IIB or IIX fibers and ~1.3-fold greater for hybrid (IIB/X) versus IIB fibers. In contrast, AICAR-stimulated glucose uptake was ~1.5-fold greater for IIB versus IIA fibers. A secondary objective was to assess insulin resistance of single fibers from obese versus lean Zucker rats. Genotype differences were observed for insulin-stimulated glucose uptake and inhibitor κB (IκB)-β abundance in single fibers (obese less than lean), with decrements for glucose uptake (44-58%) and IκB-β (25-32%) in each fiber type. This novel method creates a unique opportunity for future research focused on understanding muscle glucose uptake at the cellular level.
authors.affiliation: Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: James G
authors.initials: JG
authors.lastname: Mackrell
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Cartee
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D003847:Deoxyglucose / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology*; D005838:Genotype; D005947:Glucose / Q000235:genetics / Q000378:metabolism*; D051550:I-kappa B Kinase / Q000235:genetics / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology; D007333:Insulin Resistance; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D020033:Protein Isoforms; D051381:Rats; D017208:Rats, Wistar; D011924:Rats, Zucker; D012265:Ribonucleotides / Q000494:pharmacology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C515694:Appl1 protein, rat; D007328:Insulin; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D012265:Ribonucleotides; D000620:Aminoimidazole Carboxamide; D003847:Deoxyglucose; D051550:I-kappa B Kinase; D018995:Myosin Heavy Chains; C031143:AICA ribonucleotide; D005947:Glucose