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Skeletal muscle ultrastructural and biochemical alterations induced by experimental hyperthyroidism
A Crespo Armas1, H J Finol, B Anchustegui
1Cátedra de Fisiología, Universidad Central de Venezuela, Caracas.
Acta Cientifica Venezolana
|January 1, 1993
Summary
High doses of thyroxine (T4) increased mitochondrial respiration in rat muscles. However, muscle fibers atrophied, and mitochondria showed structural changes and autophagic vacuoles, indicating cellular damage.
Area of Science:
- Biochemistry
- Cell Biology
- Physiology
Background:
- Thyroxine (T4) is a key thyroid hormone regulating metabolism.
- Understanding T4's effects on muscle mitochondria is crucial for metabolic research.
Purpose of the Study:
- To investigate the impact of high-dose T4 treatment on mitochondrial respiration and structure in rat skeletal muscles.
- To assess alterations in muscle fiber morphology and mitochondrial integrity.
Main Methods:
- Isolated mitochondria from Soleus (slow-twitch) and EDL (fast-twitch) rat muscles.
- Measured state 3 rate respiration and phosphorylation efficiency (ADP/O ratio).
- Examined muscle fiber and mitochondrial structure using microscopy.
Main Results:
- Increased oxygen consumption in state 3 respiration for both muscle types.
- No changes in phosphorylation efficiency or mitochondrial coupling.
- Observed muscle fiber atrophy and mitochondrial structural alterations.
- Detected abundant autophagic vacuoles containing mitochondrial debris and other cellular components.
Conclusions:
- High-dose T4 enhances mitochondrial respiration but induces muscle fiber atrophy and mitochondrial damage.
- Cellular damage is evidenced by mitochondrial structural changes and autophagosome accumulation.
- T4's metabolic effects are complex, involving both functional enhancement and structural toxicity in skeletal muscle.