title: Electrical Impedance Myography to Detect the Effects of Electrical Muscle Stimulation in Wild Type and Mdx Mice.
abstract: OBJECTIVE
  Tools to better evaluate the impact of therapy on nerve and muscle disease are needed. Electrical impedance myography (EIM) is sensitive to neuromuscular disease progression as well as to therapeutic interventions including myostatin inhibition and antisense oligonucleotide-based treatments. Whether the technique identifies the impact of electrical muscle stimulation (EMS) is unknown.
  
  
  METHODS
  Ten wild-type (wt) C57B6 mice and 10 dystrophin-deficient (mdx) mice underwent 2 weeks of 20 min/day EMS on left gastrocnemius and sham stimulation on the right gastrocnemius. Multifrequency EIM data and limb girth were obtained before and at the conclusion of the protocol. Muscle weight, in situ force measurements, and muscle fiber histology were also assessed at the conclusion of the study.
  
  
  RESULTS
  At the time of sacrifice, muscle weight was greater on the EMS-treated side than on the sham-stimulated side (p = 0.018 for wt and p = 0.007 for mdx). Similarly, in wt animals, EIM parameters changed significantly compared to baseline (resistance (p = 0.009), reactance (p = 0.0003) and phase (p = 0.002); these changes were due in part to reductions in the EIM values on the EMS-treated side and elevations on the sham-simulated side. Mdx animals showed analogous but non-significant changes (p = 0.083, p = 0.064, and p = 0.57 for resistance, reactance and phase, respectively). Maximal isometric force trended higher on the stimulated side in wt animals only (p = 0.06). Myofiber sizes in wt animals were also larger on the stimulated side than on the sham-stimulated side (p = 0.034); no significant difference was found in the mdx mice (p = 0.79).
  
  
  CONCLUSIONS
  EIM is sensitive to stimulation-induced muscle alterations in wt animals; similar trends are also present in mdx mice. The mechanisms by which these EIM changes develop, however, remains uncertain. Possible explanations include longer-term trophic effects and shorter-term osmotic effects.
authors.affiliation: From the Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, 02215, United States of America.
authors.forename: Jia
authors.initials: J
authors.lastname: Li
authors.affiliation: From the Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, 02215, United States of America.
authors.forename: Sung
authors.initials: S
authors.lastname: Yim
authors.affiliation: From the Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, 02215, United States of America.
authors.forename: Adam
authors.initials: A
authors.lastname: Pacheck
authors.affiliation: From the Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, 02215, United States of America.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Sanchez
authors.affiliation: From the Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, 02215, United States of America.
authors.forename: Seward B
authors.initials: SB
authors.lastname: Rutkove
mesh_terms: D000818:Animals; D017097:Electric Impedance; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods*; D005121:Extremities / Q000033:anatomy & histology / Q000502:physiology; D008297:Male; D008810:Mice, Inbred C57BL; D018101:Mice, Inbred mdx; D009119:Muscle Contraction / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology*; D009929:Organ Size; D013045:Species Specificity