Differential susceptibility of muscles to myotonia and force impairment in a mouse model of myotonic dystrophy.
Muscle Nerve
; 43(6): 818-27, 2011 Jun.
Article
in En
| MEDLINE
| ID: mdl-21404300
ABSTRACT
INTRODUCTION:
Myotonic dystrophy, or dystrophia myotonica (DM), is characterized by prominent muscle wasting and weakness as well as delayed muscle relaxation resulting from persistent electrical discharges.METHODS:
We hypothesized heterogeneity among muscles in degree of weakness and myotonia in an expanded [(CUG)(250)] repeats transgenic (HSA(LR)) mouse DM model. Muscle contraction was compared among diaphragm, extensor digitorum longus (EDL), and soleus muscles.RESULTS:
Myotonia was found only in EDL, as manifested by longer late-relaxation time and elevated myotonic index. EDL, but not the other two muscles, had impaired force over a wide range of stimulation frequencies. During fatigue-inducing stimulation, DM EDL muscle force per cross-sectional area was significantly impaired during 25-Hz stimulation, whereas there were no differences in fatigue response for DM diaphragm or soleus.CONCLUSION:
In an expanded repeats model of DM the EDL is more susceptible to myotonia and force impairment than muscles with lower proportions of fast-twitch fibers.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Muscle, Skeletal
/
Muscle Weakness
/
Genetic Predisposition to Disease
/
Muscle Strength
/
Myotonic Dystrophy
Type of study:
Diagnostic_studies
/
Prognostic_studies
Limits:
Animals
Language:
En
Journal:
Muscle Nerve
Year:
2011
Document type:
Article
Affiliation country:
United States