title: Ipsilateral inspiratory intercostal muscle activity after C2 spinal cord hemisection in rats.
abstract: BACKGROUND
  Upper cervical spinal cord hemisection causes paralysis of the ipsilateral hemidiaphragm; however, the effect of C2 hemisection on the function of the intercostal muscles is not clear. We hypothesized that C2 hemisection would eliminate inspiratory intercostal activity ipsilateral to the injury and that some activity would return in a time-dependent manner.
  
  
  METHODS
  Female Sprague Dawley rats were anesthetized with urethane and inspiratory intercostal electromyogram (EMG) activity was recorded in control rats, acutely injured C2 hemisected rats, and at 1 and 16 weeks post C2 hemisection.
  
  
  RESULTS
  Bilateral recordings of intercostal EMG activity showed that inspiratory activity was reduced immediately after injury and increased over time. EMG activity was observed first in rostral spaces followed by recovery occurring in caudal spaces. Theophylline increased respiratory drive and increased intercostal activity, inducing activity that was previously absent.
  
  
  CONCLUSIONS
  These results suggest that there are crossed, initially latent, respiratory connections to neurons innervating the intercostal muscles similar to those innervating phrenic motor neurons.
authors: M
authors: M
authors: Beth Zimmer
authors: Joshua S
authors: JS
authors: Grant
authors: Angelo E
authors: AE
authors: Ayar
authors: Harry G
authors: HG
authors: Goshgarian
mesh_terms: D000818:Animals; D066193:Cervical Cord / Q000293:injuries / Q000503:physiopathology*; D003964:Diaphragm / Q000294:innervation* / Q000502:physiology; D019054:Evoked Potentials, Motor; D005260:Female; D007366:Intercostal Muscles / Q000294:innervation* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013119:Spinal Cord Injuries / Q000503:physiopathology*
keywords: Intercostal muscles; Latent respiratory synaptic pathways; Spinal cord injury; Theophylline