Original Paper

Journal of Muscle Research and Cell Motility

, Volume 28, Issue 4, pp 203-217

First online:

Effects of chronic electrical stimulation on long-term denervated muscles of the rabbit hind limb

  • Zoe AshleyAffiliated withMuscle Research Group, Department of Human Anatomy & Cell Biology, School of Biomedical Sciences, University of Liverpool
  • , Stanley SalmonsAffiliated withMuscle Research Group, Department of Human Anatomy & Cell Biology, School of Biomedical Sciences, University of Liverpool Email author 
  • , Simona BoncompagniAffiliated withIIM Interuniversity Institute of Myology, Centro Scienze dell’Invecchiamento (Center for Research on Ageing), Università G. d’Annunzio
  • , Feliciano ProtasiAffiliated withIIM Interuniversity Institute of Myology, Centro Scienze dell’Invecchiamento (Center for Research on Ageing), Università G. d’Annunzio
  • , Michael RussoldAffiliated withMuscle Research Group, Department of Human Anatomy & Cell Biology, School of Biomedical Sciences, University of LiverpoolRehabilitation Research Centre, University of Sydney
  • , Hermann LanmullerAffiliated withDepartment of Biomedical Engineering & Physics, University of Vienna, AKH
  • , Winfried MayrAffiliated withDepartment of Biomedical Engineering & Physics, University of Vienna, AKH
  • , Hazel SutherlandAffiliated withMuscle Research Group, Department of Human Anatomy & Cell Biology, School of Biomedical Sciences, University of Liverpool
  • , Jonathan C. JarvisAffiliated withMuscle Research Group, Department of Human Anatomy & Cell Biology, School of Biomedical Sciences, University of Liverpool

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Abstract

We investigated the extent to which activity induced by chronic electrical stimulation could restore the mass and contractile function of rabbit tibialis anterior (TA) muscles that had undergone atrophy as a result of prolonged denervation. Denervation was carried out by selectively interrupting the motor nerve branches to the ankle dorsiflexors in one hind limb. Stimulators were implanted, with electrodes on the superficial and deep surfaces of the denervated TA muscle. Ten weeks later, the mass and mid-belly cross-sectional area (CSA) of TA muscles subjected to denervation alone had fallen to approximately 40% of normal. At this stage, stimulators in the other rabbits were activated for 1 h/day to deliver 20-ms rectangular bipolar constant-current pulses of 4 mA amplitude at 20 Hz with a duty cycle of 1s ON/2s OFF, a total of 24,000 impulses/day. The animals were examined after a further 2, 6 or 10 weeks. Stimulation restored the wet weight of the denervated muscles to values not significantly different to those of normal, innervated controls. It increased CSA from 39% to 66% of normal, and there was a commensurate increase in maximum isometric tetanic force from 27% to 50% of normal. Light and electron microscopic examination revealed a marked improvement in the size, packing, and internal organization of the stimulated-denervated muscle fibres, suggestive of an ongoing process of restoration. Excitability, contractile speed, power, and fatigue resistance had not, however, been restored to normal levels after 10 weeks of stimulation. Similar results were found for muscles that had been denervated for 39 weeks and then stimulated for 12 weeks. The study demonstrates worthwhile benefits of long-term electrical stimulation in the treatment of established denervation atrophy.

Keywords

Denervated muscle Electrical stimulation Rabbit Tibialis anterior muscle Implantable device Long-term Atrophy Physiology Light microscopy Electron microscopy