title: Optimizing Electrical Stimulation for Promoting Satellite Cell Proliferation in Muscle Disuse Atrophy.
abstract: OBJECTIVE
  The aim of this study was to investigate the optimal electrical stimulation (ES) protocol in attenuating disuse muscle atrophy by influencing satellite cell activity.
  
  
  METHODS
  This study used a pretest-posttest design. Six ES protocols of different duration (3 hrs day or 2 × 3 hrs day) and frequencies (2, 10, or 20 Hz) were applied on the soleus muscle in mice (n = 8 in each group) that were hindlimb-suspended for 14 days. Muscle mass, cross-sectional area and fiber-type composition, and peak tetanic force of the muscles were measured. Immunohistochemical staining was used to evaluate satellite cell content, activation, proliferation, and differentiation. Cell apoptosis was detected by TdT-mediated dUTP nick end labeling (TUNEL) assay.
  
  
  RESULTS
  ES at 2 Hz for 2 × 3 hrs day achieved the best effect in attenuating the loss of muscle fiber cross-sectional area and force. This stimulation parameter led to a 1.2-fold increase in satellite cell proliferation and was effective in rescuing cells from apoptosis. Besides, satellite cells in the atrophic muscles required different stimulation protocols for different cellular activities such as activation, proliferation, and myogenic differentiation.
  
  
  CONCLUSIONS
  This study showed that ES at 2 Hz for 2 × 3 hrs day is the optimal protocol for counteracting muscle disuse atrophy.
authors.affiliation: From the Muscle Physiology Laboratory, Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (QW, SSY, KKC, EWY); School of Life Sciences, The Chinese University of Hong Kong, Hong Kong (SWA, WWL); and State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China (YHL, ZQD).
authors.forename: Qing
authors.initials: Q
authors.lastname: Wan
authors.forename: Simon S
authors.initials: SS
authors.lastname: Yeung
authors.forename: Kwok Kuen
authors.initials: KK
authors.lastname: Cheung
authors.forename: Shannon W
authors.initials: SW
authors.lastname: Au
authors.forename: Wendy W
authors.initials: WW
authors.lastname: Lam
authors.forename: Ying Hui
authors.initials: YH
authors.lastname: Li
authors.forename: Zhong Quan
authors.initials: ZQ
authors.lastname: Dai
authors.forename: Ella W
authors.initials: EW
authors.lastname: Yeung
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D004195:Disease Models, Animal; D004558:Electric Stimulation; D004599:Electric Stimulation Therapy / Q000379:methods*; D008807:Mice, Inbred BALB C; D008853:Microscopy; D018657:Muscle Fibers, Slow-Twitch / Q000473:pathology; D018482:Muscle, Skeletal / Q000473:pathology*; D009133:Muscular Atrophy / Q000473:pathology*; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D032496:Satellite Cells, Skeletal Muscle / Q000473:pathology*
chemical_list: D012333:RNA, Messenger; D018995:Myosin Heavy Chains