title: Differences in energy metabolism and neuromuscular transmission between 30-Hz and 100-Hz stimulation in rat skeletal muscle.
abstract: OBJECTIVE
  To examine differences in energy metabolism and neuromuscular transmission failure in rat hindlimb muscles subjected to electric stimulation at different frequencies.
  
  
  METHODS
  Experimental animal study.
  
  
  METHODS
  Bioenergetic Research Center at Otsuka Pharmaceutical Company, Otsuka, Japan.
  
  
  METHODS
  Thirty-two 25-week-old male Wistar-Kyoto rats.
  
  
  METHODS
  With the rat under general anesthesia, the sciatic nerve was electrically stimulated at 30Hz and 100Hz to induce muscle contraction.
  
  
  METHODS
  Energy level and intracellular pH of muscles by phosphorus-31 magnetic resonance spectroscopy ((31)P-MRS); M-wave amplitude of muscles by electromyography.
  
  
  RESULTS
  During the first 4 minutes under stimulation at 30Hz and at 100Hz, energy level and intracellular pH dropped to their lowest values (p <.05 or p <.01); the values then recovered with time. Recovery rates of energy level and intracellular pH during stimulation at 100Hz were greater than those observed during stimulation at 30Hz. The M-wave amplitude during 100-Hz stimulation was permanently and significantly lower than that measured during 30-Hz stimulation (p <.01), and the recovery rate of M-wave amplitude after stimulation at 100Hz was slower than that after stimulation at 30Hz.
  
  
  CONCLUSIONS
  Neuromuscular transmission failure was greater with 100-Hz stimulation than with 30-Hz stimulation. This finding may account for the rapid recovery of energy level and intracellular pH that occurs with stimulation at 100Hz.
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, University of Tokushima, Tokushima, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Takata
authors.forename: T
authors.initials: T
authors.lastname: Ikata
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D004576:Electromyography; D004734:Energy Metabolism / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D007424:Intracellular Fluid / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D009469:Neuromuscular Junction / Q000502:physiology*; D010759:Phosphorus Isotopes; D005082:Physical Exertion / Q000502:physiology; D051381:Rats; D011921:Rats, Inbred WKY; D012584:Sciatic Nerve / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D010759:Phosphorus Isotopes