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Response to caffeine and ryanodine receptor isoforms in mouse skeletal muscles
R Rossi1, R Bottinelli, V Sorrentino
1Institute of Human Physiology, University of Pavia, I-27100 Pavia, Italy.
Abstract:
The response to caffeine was studied in mouse muscles [diaphragm, soleus, and extensor digitorum longus (EDL)] with different ryanodine receptor isoform (RyR1, RyR3) composition and in single permeabilized muscle fibers dissected from diaphragm of wild-type (WT) and RyR3-deficient (RyR3-/-) mice at 1, 15, 30, and 60 postnatal days (PND). The caffeine response decreased during development, and, in adult mice, was greater in diaphragm, lower in EDL, and intermediate in soleus. This suggests a direct relation between response to caffeine and RyR3 expression. The lack of RyR3 reduced caffeine response in young, but not in adult mice, and did not abolish the age-dependent variation and the intermuscle differences. In diaphragm single fibers, the response to caffeine increased during development and was reduced in fibers lacking RyR3 both at 15 and 60 PND. A population of fibers highly responsive to caffeine was present in adult WT and disappeared in RyR3-/-. The results confirm the contribution of RyR3 to calcium release for contractile response and clarify the contribution of RyR3 to developmental changes and intermuscle differences.
Insights
Caffeine response in mouse muscles changes with age and muscle type, influenced by RyR3. Lack of RyR3 impacts young mice more, affecting calcium release for muscle contraction.
Area of Science:
- Muscle Physiology
- Calcium Signaling
- Developmental Biology
Background:
- Ryanodine receptors (RyRs) are critical for muscle excitation-contraction coupling.
- RyR isoforms, particularly RyR1 and RyR3, exhibit differential expression and function across muscle types and developmental stages.
- Understanding the specific role of RyR3 in caffeine-induced calcium release is essential for elucidating muscle function.
Purpose of the Study:
- To investigate the developmental and inter-muscle variations in caffeine response in mouse skeletal muscles.
- To determine the specific contribution of the RyR3 isoform to caffeine sensitivity during muscle development.
- To clarify the role of RyR3 in age-dependent and muscle-specific differences in calcium release.
Main Methods:
- Caffeine-induced responses were measured in diaphragm, soleus, and extensor digitorum longus (EDL) muscles from wild-type and RyR3-deficient mice at various postnatal days (PND).
- Single permeabilized muscle fibers from diaphragm were used to analyze caffeine sensitivity at the cellular level.
- Comparisons were made across different ages (1, 15, 30, 60 PND) and genotypes (WT, RyR3-/-).
Main Results:
- Caffeine response generally decreased with age across all studied muscles.
- In adult mice, diaphragm showed the greatest response, followed by soleus, and then EDL.
- RyR3 deficiency reduced caffeine response in young mice but not significantly in adults, while preserving age-dependent and inter-muscle variations.
- Diaphragm single fibers showed increased caffeine response with development, which was diminished in RyR3-deficient fibers.
Conclusions:
- RyR3 significantly contributes to calcium release for muscle contraction, particularly in younger mice.
- RyR3 plays a key role in mediating developmental changes and inter-muscle differences in caffeine sensitivity.
- The disappearance of a highly caffeine-responsive fiber population in adult RyR3-deficient mice highlights RyR3's importance in mature muscle function.