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Morphogenesis of the mitochondrial alterations in muscle diseases
Abstract:
In this paper we present sequential morphologic changes produced in rat muscle mitochondria. Respiratory toxins such as crotoxin (rattle-snake venom) and 2,4-dinitrophenol (DNP-an uncoupler of oxidative phosphorylation) were injected in rat quadriceps muscle and the mitochondrial alterations were studied at various time intervals. The series of mitochondrial changes consisted of rounding and swelling of mitochondria, unfolding of the cristae as straight lines, formation of the concentric rings, appearance of paracrystalline inclusions, formation of multiple vesicles and finally vacuole formation. These changes were comparable to the range of mitochondrial alterations seen in the human material examined. Similarity of the time-related mitochondrial changes in the rat to the spectrum of changes observed in human muscle biopsies suggests that the mitochondrial alteration in the human muscle disorders is a stepwise process in which respiratory alterations and calcium ion may play a role.
Insights
Mitochondrial changes in rat muscle, induced by toxins, follow a sequential pattern. These observed changes in rat muscle mitochondria are comparable to those seen in human muscle disorders, suggesting a stepwise process.
Area of Science:
- Mitochondrial biochemistry
- Cellular pathology
- Toxicology
Background:
- Mitochondria are crucial for cellular energy production.
- Disruptions in mitochondrial function are implicated in various human muscle diseases.
- Understanding the dynamic changes in mitochondria is key to understanding disease progression.
Purpose of the Study:
- To document the sequential morphologic changes in rat muscle mitochondria following exposure to respiratory toxins.
- To compare these induced changes with alterations observed in human muscle biopsies.
- To elucidate the potential role of respiratory dysfunction and calcium ions in mitochondrial pathology.
Main Methods:
- Injection of respiratory toxins (crotoxin and 2,4-dinitrophenol) into rat quadriceps muscle.
- Microscopic examination of mitochondrial morphology at various time points post-injection.
- Comparative analysis of rat mitochondrial changes with human muscle biopsy data.
Main Results:
- A distinct series of mitochondrial alterations was observed, including rounding, swelling, cristae unfolding, concentric ring formation, paracrystalline inclusions, vesicle formation, and vacuolation.
- These sequential changes occurred in a predictable, time-dependent manner.
- The observed spectrum of mitochondrial alterations in rats closely mirrored those found in human muscle disorders.
Conclusions:
- Mitochondrial alterations in human muscle disorders likely represent a stepwise process.
- Respiratory toxins can induce a range of mitochondrial changes similar to those seen in human myopathies.
- Further research should investigate the roles of impaired respiration and calcium ion dysregulation in the pathogenesis of mitochondrial myopathies.