title: Bone and muscle structure and quality preserved by active versus passive muscle exercise on a new stepper device in 21 days tail-suspended rats.
abstract: Human performance in microgravity is characterized by reversed skeletal muscle actions in terms of active vs. passive mode contractions of agonist/antagonist groups that may challenge principal biodynamics (biomechanical forces translated from muscle to bone) of the skeletal muscle-bone unit. We investigated active vs. passive muscle motions of the unloaded hindlimb skeletal muscle-bone unit in the 21 days tail-suspended (TS) rat using a newly designed stepper exercise device. The regimen included both active mode motions (TSA) and passive mode motions (TSP). A TS-only group and a normal cage group (CON) served as positive or negative controls. The muscle and bone decrements observed in TS-only group were not seen in the other groups except TSP. Active mode motions supported femur and tibia bone quality (5% BMD, 10% microtrabecular BV/TV, Tb.Th., Tb.N. parameters), whole soleus muscle/myofiber size and type II distribution, 20% increased sarcolemma NOS1 immunosignals vs. CON, with 25% more hybrid fiber formation (remodeling sign) for all TS groups. We propose a new custom-made stepper device to be used in the TS rat model that allows for detailed investigations of the unique biodynamic properties of the muscle-bone unit during resistive-load exercise countermeasure trials on the ground or in microgravity.
authors.affiliation: Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China.
authors.forename: L W
authors.initials: LW
authors.lastname: Sun
authors.forename: D
authors.initials: D
authors.lastname: Blottner
authors.forename: H Q
authors.initials: HQ
authors.lastname: Luan
authors.forename: M
authors.initials: M
authors.lastname: Salanova
authors.forename: C
authors.initials: C
authors.lastname: Wang
authors.forename: H J
authors.initials: HJ
authors.lastname: Niu
authors.forename: D
authors.initials: D
authors.lastname: Felsenberg
authors.forename: Y B
authors.initials: YB
authors.lastname: Fan
mesh_terms: D015502:Absorptiometry, Photon; D000818:Animals; D001696:Biomechanical Phenomena / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D001842:Bone and Bones / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D004576:Electromyography; D005455:Fluorescent Antibody Technique; D019417:Hindlimb Suspension / Q000502:physiology*; D007150:Immunohistochemistry; D035002:Lower Extremity / Q000502:physiology; D015915:Motion Therapy, Continuous Passive; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism; D009929:Organ Size; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D055070:Resistance Training; D013977:Tibia / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D014057:Tomography, X-Ray Computed
chemical_list: D052248:Nitric Oxide Synthase Type I