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Intermittent claudication and muscle fiber fine structure: morphometric data on mitochondrial volumes
Ultrastructural Pathology
|October 1, 1980
Summary
Patients with intermittent claudication show increased mitochondrial volume in oxidative muscle fibers, suggesting adaptation to leg ischemia. This mitochondrial increase correlates with disease severity and impacts walking tolerance.
Area of Science:
- Muscle physiology
- Mitochondrial biology
- Ischemia research
Background:
- Intermittent claudication is characterized by leg pain during exercise due to peripheral artery disease.
- Mitochondrial dysfunction is implicated in various muscle pathologies.
- Understanding muscle fiber adaptations in response to ischemia is crucial for therapeutic development.
Purpose of the Study:
- To investigate mitochondrial volume densities (Vmit) in different muscle fiber types (Type 1, Type 2A, Type 2B) in patients with unilateral intermittent claudication.
- To compare Vmit between asymptomatic and symptomatic legs and correlate findings with clinical data and disease severity.
- To explore fiber type-specific adaptations to ischemia and the influence of hypoxia on mitochondrial content.
Main Methods:
- Bilateral muscle biopsies were obtained from 22 patients with unilateral intermittent claudication.
- Mitochondrial volume densities (Vmit) were estimated for Type 1, Type 2A, and Type 2B fibers.
- Vmit data were compared between asymptomatic and symptomatic legs and correlated with clinical parameters like walking tolerance and lesion severity.
Main Results:
- In both legs, Vmit followed the order: Vmit 1 > Vmit 2A > Vmit 2B.
- Total mitochondrial volume (Vmit Tot) was higher in symptomatic legs, primarily due to increased Vmit in oxidative fibers (Type 1 and Type 2A).
- Vmit in asymptomatic legs correlated with functional tests, while in symptomatic legs, only Vmit 2A showed correlation; Vmit Tot correlated with stenosis severity.
Conclusions:
- Fiber type-specific adaptation to ischemia occurs, characterized by increased mitochondrial content in oxidative fibers.
- Hypoxia associated with intermittent claudication may influence the regulation of mitochondrial protein synthesis or degradation.
- Mitochondrial adaptations in oxidative fibers represent a compensatory response to chronic ischemia, impacting exercise capacity.