Systemic inflammatory response syndrome increases immobility-induced neuromuscular weakness.
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.
Fink
Heidrun
H
Klinik für Anaesthesiologie, Technischen Universität München, Klinikum rechts der Isar, Munich, Germany. h.fink@lrz.tum.de
Helming
Marc
M
Unterbuchner
Christoph
C
Lenz
Andrea
A
Neff
Frauke
F
Martyn
J A Jeevendra
JA
Blobner
Manfred
M
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*