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Published on: November 3, 2013
Desensitization in the innervated and in the chronically denervated soleus muscle of the mouse
Abstract:
1 A study was made of desensitization in chronically denervated and in normally innervated mouse soleus muscles. 2 Very high concentrations of acetylcholine produced small contractions of the innervated muscles; these were reduced in size when the addition was repeated 1 min after wash-out. 3 Desensitization in innervated muscles was receptor specific: contractions in response to KCl and caffeine were not reduced following acetylcholine, nor did KCl produce desensitization. 4 In chronically denervated muscles non-specific desensitization was observed if acetylcholine was added in the presence of low concentrations of acetylcholine or carbachol. Contractions to KCl but not to caffeine were reduced. KCl produced a similar kind of desensitization. 5 After washing out moderate or supramaximal concentrations from the chronically denervated muscle no desensitization was observed. However, 1 min after washout of very high concentrations the muscle was non-specifically desensitized. 6 It is concluded that relatively high concentrations of acetylcholine are required to produce specific desensitization in the soleus muscle. Chronically denervated muscles, being supersensitive, show non-specific loss of sensitivity with concentrations of acetylcholine too low to produce specific desensitization.
Insights
High acetylcholine concentrations cause specific desensitization in mouse soleus muscles. Denervated muscles show non-specific desensitization even at lower acetylcholine levels due to supersensitivity.
Area of Science:
- Neuroscience
- Muscle Physiology
Background:
- Muscle denervation leads to acetylcholine receptor supersensitivity.
- Understanding desensitization mechanisms is crucial for neuromuscular research.
Purpose of the Study:
- To investigate acetylcholine-induced desensitization in innervated and chronically denervated mouse soleus muscles.
- To differentiate between specific and non-specific desensitization pathways.
Main Methods:
- Comparative study of mouse soleus muscles (innervated vs. denervated).
- Application of varying acetylcholine concentrations and related compounds (KCl, carbachol).
- Assessment of muscle contraction responses and desensitization following washout periods.
Main Results:
- Innervated muscles showed receptor-specific desensitization to high acetylcholine concentrations.
- Denervated muscles exhibited non-specific desensitization with lower acetylcholine concentrations, affecting KCl but not caffeine responses.
- Very high acetylcholine concentrations induced non-specific desensitization in denervated muscles after washout.
Conclusions:
- Specific desensitization in soleus muscle requires high acetylcholine concentrations.
- Denervated, supersensitive muscles display non-specific desensitization at lower acetylcholine levels than needed for specific desensitization.
