Differential susceptibility of muscles to myotonia and force impairment in a mouse model of myotonic dystrophy

M Moyer, DS Berger, AN Ladd… - Muscle & nerve, 2011 - Wiley Online Library
M Moyer, DS Berger, AN Ladd, E Van Lunteren
Muscle & nerve, 2011•Wiley Online Library
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 (HSALR) mouse DM model. Muscle contraction was compared among
diaphragm, extensor digitorum longus (EDL), and soleus muscles. Results: Myotonia was …
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 (HSALR) 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. Muscle Nerve, 2011
Wiley Online Library
Show moreShow less
Save Cite Cited by 8 Related articles All 6 versions