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Soleus-specific myopathy induced by passive stretching under local tetanus
Muscle & Nerve
|October 1, 1990
Summary
Tetanus toxin injection into rat gastrocnemius muscle induced myopathic changes in the soleus muscle, including fiber damage and fibrosis. These changes were accompanied by elevated muscle enzymes and T-tubule alterations.
Area of Science:
- Muscle pathology
- Neuromuscular disorders
Background:
- Tetanus toxin is known to cause muscle spasms.
- The effects of sustained muscle stretch following tetanus toxin exposure on muscle histology are not well understood.
Purpose of the Study:
- To investigate the histopathological changes in the soleus muscle of rats after tetanus toxin injection and sustained dorsiflexion.
- To examine the temporal progression of these myopathic alterations.
Main Methods:
- Adult albino rats were injected with tetanus toxin in the gastrocnemius muscle.
- The ankle joint was subjected to sustained dorsiflexion for 2 to 14 days.
- Histological, electron microscopy, and serum enzyme analyses were performed on soleus muscles.
Main Results:
- Histology revealed myopathic changes: fiber diameter variation, myonecrosis, fibrosis, and regeneration.
- Electron microscopy showed T-tubule derangement in the early degenerative phase.
- Soleus muscle size and weight increased; serum GOT, LDH, and CK levels were elevated.
- Fibrosis developed progressively from 3 days post-tetanus.
Conclusions:
- Sustained dorsiflexion following tetanus toxin injection induces significant myopathic changes in the soleus muscle.
- Early T-tubule abnormalities and subsequent fibrosis are key features of this induced myopathy.
- The findings provide insights into the pathomechanisms of toxin-induced muscle damage and repair.