title: Endurance training facilitates myoglobin desaturation during muscle contraction in rat skeletal muscle.
abstract: At onset of muscle contraction, myoglobin (Mb) immediately releases its bound O2 to the mitochondria. Accordingly, intracellular O2 tension (PmbO2) markedly declines in order to increase muscle O2 uptake (mVO2). However, whether the change in PmbO2 during muscle contraction modulates mVO2 and whether the O2 release rate from Mb increases in endurance-trained muscles remain unclear. The purpose of this study was, therefore, to determine the effect of endurance training on O2 saturation of Mb (SmbO2) and PmbO2 kinetics during muscle contraction. Male Wistar rats were subjected to a 4-week swimming training (Tr group; 6 days per week, 30 min × 4 sets per day) with a weight load of 2% body mass. After the training period, deoxygenated Mb kinetics during muscle contraction were measured using near-infrared spectroscopy under hemoglobin-free medium perfusion. In the Tr group, the VmO2peak significantly increased by 32%. Although the PmbO2 during muscle contraction did not affect the increased mVO2 in endurance-trained muscle, the O2 release rate from Mb increased because of the increased Mb concentration and faster decremental rate in SmbO2 at the maximal twitch tension. These results suggest that the Mb dynamics during muscle contraction are contributing factors to faster VO2 kinetics in endurance-trained muscle.
authors: 1] Faculty of Health and Sports Science, Doshisha University, Kyotanabe 610-0394, Japan [2] Faculty of Human Sciences, Kanazawa University, Kanazawa 920-1192, Japan.
authors: Hisashi
authors: H
authors: Takakura
authors: 1] Faculty of Human Sciences, Kanazawa University, Kanazawa 920-1192, Japan [2] Department of Health Promotion Science, Tokyo Metropolitan University, Hachioji 192-0397, Japan.
authors: Yasuro
authors: Y
authors: Furuichi
authors: Faculty of Human Sciences, Kanazawa University, Kanazawa 920-1192, Japan.
authors: Tatsuya
authors: T
authors: Yamada
authors: Department of Biochemistry and Molecular Medicine, University of California Davis, Davis 95616-8635, USA.
authors: Thomas
authors: T
authors: Jue
authors: Faculty of Human Sciences, Kanazawa University, Kanazawa 920-1192, Japan.
authors: Minoru
authors: M
authors: Ojino
authors: Faculty of Sports and Health Science, Ritsumeikan University, Kusatsu 525-8577, Japan.
authors: Takeshi
authors: T
authors: Hashimoto
authors: Department of Physiology, Aichi Medical University, Nagakute 480-1195, Japan.
authors: Satoshi
authors: S
authors: Iwase
authors: Faculty of Health and Sports Science, Doshisha University, Kyotanabe 610-0394, Japan.
authors: Tatsuya
authors: T
authors: Hojo
authors: Faculty of Health and Sports Science, Doshisha University, Kyotanabe 610-0394, Japan.
authors: Tetsuya
authors: T
authors: Izawa
authors: Faculty of Human Sciences, Kanazawa University, Kanazawa 920-1192, Japan.
authors: Kazumi
authors: K
authors: Masuda
mesh_terms: D000818:Animals; D007700:Kinetics; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism*; D009211:Myoglobin / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010805:Physical Conditioning, Animal; D010807:Physical Endurance / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D019265:Spectroscopy, Near-Infrared; D013550:Swimming
chemical_list: D009211:Myoglobin; D010100:Oxygen