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Ultrastructural changes in the cardiomyopathy of dystrophic hamsters and mice
1University of Liverpool, Department of Zoology.
Insights
In animal models of muscular dystrophy, cardiac and skeletal muscle cells show similar damage. This suggests a shared genetic cause and implicates calcium dysregulation in muscle cell degeneration.
Area of Science:
- Cell Biology
- Biochemistry
- Genetics
Background:
- Muscular dystrophy in animals affects both skeletal and cardiac muscle.
- Understanding the cellular mechanisms underlying muscle damage is crucial.
Purpose of the Study:
- To investigate the ultrastructural changes in cardiac muscle cells of dystrophic mice and hamsters.
- To compare cellular damage in cardiac and skeletal muscles.
- To explore the role of calcium ions ([Ca]i) in muscle cell degradation.
Main Methods:
- Ultrastructural analysis of cardiac muscle cells from dystrophic mice and hamsters (22-40 weeks).
- Comparison of cellular damage patterns between cardiac and skeletal muscles.
- Experimental manipulation of intracellular calcium levels ([Ca]i) in normal cardiac muscle.
Main Results:
- Severe cardiomyopathy observed in dystrophic mice and hamsters, correlating with skeletal muscle damage.
- Degradative changes in the myofilament apparatus and mitochondrial ultrastructure (swelling, septation, division) were characteristic.
- Similar ultrastructural changes were induced in normal cardiac muscle by experimentally raising intracellular calcium ([Ca]i).
Conclusions:
- A single gene likely underlies the myopathy affecting both skeletal and cardiac muscles in animal dystrophy.
- Elevated intracellular calcium ([Ca]i) levels are implicated in the degenerative processes observed in muscle cells.
Abstract:
Changes in the ultrastructure of the cardiac muscle cells have been followed in dystrophic mice and hamsters (22-40 weeks of age) and in both species a severe cardiomyopathy accompanies the cellular damage of the skeletal muscle. The degradative changes of the myofilament apparatus of the heart cells and the specific changes in mitochondrial ultrastructure (including swelling, septation and apparent division) are characteristic of the cellular damage of both the dystrophic skeletal muscle and of normal cardiac muscle in which [Ca]i has been experimentally raised, confirming the suggestions that (i) the same gene is responsible for the myopathy of skeletal and cardiac muscle in animal dystrophy and (ii) that changes in [Ca]i are implicated in the degradative changes of muscle cells.