Chronically ischemic mouse skeletal muscle exhibits myopathy in association with mitochondrial dysfunction and
Iraklis I Pipinos1, Stanley A Swanson, Zhen Zhu
1Department of Surgery, University of Nebraska Medical Center, Omaha, Nebraska 68198-3280, USA. ipipinos@unmc.edu
Abstract:
A myopathy characterized by mitochondrial pathology and oxidative stress is present in patients with peripheral arterial disease (PAD). Patients with PAD differ in disease severity, mode of presentation, and presence of comorbid conditions. In this study, we used a mouse model of hindlimb ischemia to isolate and directly investigate the effects of chronic inflow arterial occlusion on skeletal muscle microanatomy, mitochondrial function and expression, and oxidative stress. Hindlimb ischemia was induced by staged ligation/division of the common femoral and iliac arteries in C57BL/6 mice, and muscles were harvested 12 wk later. Muscle microanatomy was examined by bright-field microscopy, and mitochondrial content was determined as citrate synthase activity in muscle homogenates and ATP synthase expression by fluorescence microscopy. Electron transport chain (ETC) complexes I through IV were analyzed individually by respirometry. Oxidative stress was assessed as total protein carbonyls and 4-hydroxy-2-nonenal (HNE) adducts and altered expression and activity of manganese superoxide dismutase (MnSOD). Ischemic muscle exhibited histological features of myopathy and increased mitochondrial content compared with control muscle. Complex-dependent respiration was significantly reduced for ETC complexes I, III, and IV in ischemic muscle. Protein carbonyls, HNE adducts, and MnSOD expression were significantly increased in ischemic muscle. MnSOD activity was not significantly changed, suggesting MnSOD inactivation. Using a mouse model, we have demonstrated for the first time that inflow arterial occlusion alone, i.e., in the absence of other comorbid conditions, causes myopathy with mitochondrial dysfunction and increased oxidative stress, recapitulating the muscle pathology of PAD patients.
Insights
Peripheral arterial disease (PAD) causes myopathy with mitochondrial dysfunction and oxidative stress. This study in mice shows chronic arterial occlusion alone induces these muscle pathologies, mimicking PAD.
Area of Science:
- Cardiovascular Biology
- Skeletal Muscle Physiology
- Mitochondrial Medicine
Background:
- Peripheral arterial disease (PAD) is associated with skeletal muscle myopathy, mitochondrial dysfunction, and oxidative stress.
- Patient presentation in PAD varies, complicating direct study of arterial occlusion's effects.
- A controlled model is needed to isolate the impact of arterial occlusion on muscle pathology.
Purpose of the Study:
- To investigate the direct effects of chronic inflow arterial occlusion on skeletal muscle.
- To analyze microanatomy, mitochondrial function, and oxidative stress in an ischemic hindlimb mouse model.
- To establish if isolated arterial occlusion recapitulates PAD-related muscle pathology.
Main Methods:
- Hindlimb ischemia induced by staged arterial ligation in C57BL/6 mice; muscles harvested after 12 weeks.
- Microanatomy assessed via microscopy; mitochondrial content by citrate synthase activity and ATP synthase expression.
- Electron transport chain (ETC) complex respiration, oxidative stress markers (protein carbonyls, HNE), and MnSOD analyzed.
Main Results:
- Ischemic muscle showed myopathy histological features and increased mitochondrial content.
- Significant reductions in ETC complexes I, III, and IV respiration were observed.
- Elevated protein carbonyls, HNE adducts, and MnSOD expression indicated increased oxidative stress, with potential MnSOD inactivation.
Conclusions:
- Inflow arterial occlusion alone induces myopathy with mitochondrial dysfunction and oxidative stress.
- This mouse model effectively recapitulates the skeletal muscle pathology seen in PAD patients.
- Findings highlight the direct role of reduced arterial blood flow in PAD-induced muscle damage.
