title: Systemic inflammatory response syndrome increases immobility-induced neuromuscular weakness.
abstract: OBJECTIVE
  Inflammation and immobility are comorbid etiological factors inducing muscle weakness in critically ill patients. This study establishes a rat model to examine the effect of inflammation and immobilization alone and in combination on muscle contraction, histology, and acetylcholine receptor regulation.
  
  
  METHODS
  Prospective, randomized, experimental study.
  
  
  METHODS
  Animal laboratory of a university hospital.
  
  
  METHODS
  Sprague-Dawley rats.
  
  
  METHODS
  To produce systemic inflammation, rats (n = 34) received three consecutive intravenous injections of Corynebacterium parvum on days 0, 4, and 8. Control rats (n = 21) received saline. Both groups were further divided to have one hind limb either immobilized by pinning of knee and ankle joints or sham-immobilized (surgical leg). The contralateral nonsurgical leg of each animal served as control (nonsurgical leg).
  
  
  RESULTS
  After 12 days, body weight and muscle mass were significantly reduced in all C. parvum animals compared with saline-injected rats. Immobilization led to local muscle atrophy. Normalized to muscle mass, tetanic contraction was reduced in the surgical leg after immobilization (7.64 +/- 1.91 N/g) and after inflammation (8.71 +/- 2.0 N/g; both p < .05 vs. sham immobilization and saline injection, 11.03 +/- 2.26 N/g). Histology showed an increase in inflammatory cells in all C. parvum-injected animals. Immobilization in combination with C. parvum injection had an additive effect on inflammation. Acetylcholine receptors were increased in immobilized muscles and in all muscles of C. parvum-injected animals.
  
  
  CONCLUSIONS
  The muscle weakness in critically ill patients can be replicated in our novel rat model. Inflammation and immobilization independently lead to muscle weakness.
authors.affiliation: Klinik für Anaesthesiologie, Technischen Universität München, Klinikum rechts der Isar, Munich, Germany. h.fink@lrz.tum.de
authors.forename: Heidrun
authors.initials: H
authors.lastname: Fink
authors.forename: Marc
authors.initials: M
authors.lastname: Helming
authors.forename: Christoph
authors.initials: C
authors.lastname: Unterbuchner
authors.forename: Andrea
authors.initials: A
authors.lastname: Lenz
authors.forename: Frauke
authors.initials: F
authors.lastname: Neff
authors.forename: J A Jeevendra
authors.initials: JA
authors.lastname: Martyn
authors.forename: Manfred
authors.initials: M
authors.lastname: Blobner
mesh_terms: D000818:Animals; D007103:Immobilization / Q000009:adverse effects*; D008297:Male; D018908:Muscle Weakness / Q000209:etiology*; D009422:Nervous System Diseases / Q000209:etiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018746:Systemic Inflammatory Response Syndrome / Q000150:complications*