title: Effect of High-Intensity Training in Normobaric Hypoxia on Thoroughbred Skeletal Muscle.
abstract: Hypoxic training is believed to increase endurance capacity in association with hypoxia inducible factor-1α(HIF-1α), a modulator of vascular endothelial growth factor-A (VEGF-A), and to influence activation of satellite cells (SCs). However, the effect of hypoxic training on SC activation and its relation to angiogenesis has not been thoroughly investigated. Eight Thoroughbred horses were subjected to normoxic (FIO2= 21%) or hypoxic (FIO2= 15%) training for 3 days/week (100%  [Formula: see text]) for 4 weeks. Incremental exercise tests (IET) were conducted on a treadmill under normoxia and the maximal oxygen consumption ([Formula: see text]) and running distance were measured before and after each training session. Muscle biopsy samples were obtained from the gluteus medius muscle at 6 scheduled times before, during, and one week after IET for immunohistochemical analysis and real-time RT-PCR analysis. Running distance and [Formula: see text], measured during IET, increased significantly after hypoxic training compared with normoxic training. Capillary density and mRNA expression related to SC activation (e.g., myogenin and hepatocyte growth factor) and angiogenesis (VEGF-A) increased only after hypoxic training. These results suggest that increases in mRNA expression after training enhance and prolong SC activation and angiogenesis and that nitric oxide plays an important role in these hypoxia-induced training effects.
authors.affiliation: Biological Sciences, Graduate School of Medicine, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8515, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nagahisa
authors.affiliation: Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi 329-0412, Japan.
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Mukai
authors.affiliation: Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi 329-0412, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Ohmura
authors.affiliation: Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi 329-0412, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Takahashi
authors.affiliation: Biological Sciences, Graduate School of Medicine, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8515, Japan.
authors.forename: Hirofumi
authors.identifier: 0000-0001-6462-4726
authors.initials: H
authors.lastname: Miyata
mesh_terms: D000818:Animals; D001835:Body Weight; D018592:Cross-Over Studies; D005260:Female; D017228:Hepatocyte Growth Factor / Q000235:genetics / Q000378:metabolism; D006736:Horses; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology; D018008:Myogenin / Q000235:genetics / Q000378:metabolism; D010101:Oxygen Consumption; D010807:Physical Endurance; D012333:RNA, Messenger / Q000378:metabolism; D032496:Satellite Cells, Skeletal Muscle / Q000166:cytology / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D018008:Myogenin; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D017228:Hepatocyte Growth Factor