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Updated: Aug 18, 2026
Isometric and Eccentric Force Generation Assessment of Skeletal Muscles Isolated from Murine Models of Muscular Dystrophies
Published on: January 31, 2013
A freeze-fracture study of normal and dystrophic C57BL mouse muscle
Abstract:
Freeze-fracture replicas of normal and dystrophic C57BL mouse muscle and kidney were examined to see whether here was a deficit in plasmalemmal particles which others suggest is a feature of dystrophies. When compared with normal membranes there was an increase in the particle density in dystrophic extensor digitorum longus muscle, a decrease in dystrophic soleus muscle, and no change in dystrophic kidney. Therefore there was not a general deficit in intramembrane particles in this dystrophic tissue. Indirect evidence supported the hypothesis that abnormalities in dystrophic mouse muscles are caused by abnormal motor input. The density of indentations, parallel to the T-tubule, on the flat surface of the terminal cisternae can be modulated by the motor nerve. Changes were found in indentation density in dystrophic muscle which were similar to changes seen after transection of the spinal cord in the mid-thoracic region. There were parallel changes in contractile properties and indentation density in dystrophic fibers.
Insights
This study investigated muscle and kidney membranes in dystrophic mice, finding no general deficit in plasmalemmal particles. Abnormalities in dystrophic muscles may stem from altered motor neuron input.
Area of Science:
- Biochemistry
- Cell Biology
- Neuroscience
Background:
- Duchenne muscular dystrophy is characterized by muscle degeneration.
- Previous research suggested a deficit in plasmalemmal particles in dystrophic tissues.
- The role of motor input in muscular dystrophy is not fully understood.
Purpose of the Study:
- To investigate the presence of plasmalemmal particle deficits in dystrophic mouse muscle and kidney.
- To explore the relationship between motor input and muscle abnormalities in muscular dystrophy.
Main Methods:
- Freeze-fracture electron microscopy was used to examine muscle and kidney membranes from normal and dystrophic C57BL mice.
- Particle density in plasmalemmal membranes was quantified.
- Indentation density on terminal cisternae was analyzed.
Main Results:
- No general deficit in intramembrane particles was observed in dystrophic mouse tissues.
- Particle density varied: increased in dystrophic extensor digitorum longus, decreased in dystrophic soleus muscle.
- Changes in indentation density in dystrophic muscle mirrored those seen after spinal cord transection.
- Contractile properties and indentation density showed parallel changes in dystrophic fibers.
Conclusions:
- The findings do not support a general deficit in plasmalemmal particles as a feature of this form of muscular dystrophy.
- Abnormalities in dystrophic mouse muscles may be linked to altered motor neuron input.
- Indentation density on terminal cisternae is modulated by motor nerve activity and altered in dystrophic muscle.
