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Sarcoplasmic reticulum Ca2+ pump expression in denervated skeletal muscle
L Schulte1, D Peters, J Taylor
1Department of Health Sciences, Boston University, Massachusetts 02215.
The American Journal of Physiology
|August 1, 1994
Summary
Denervation significantly reduces muscle mass and alters sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) expression in both fast-twitch and slow-twitch skeletal muscles. This impacts muscle contraction and relaxation, indicating impaired calcium handling.
Area of Science:
- Skeletal Muscle Physiology
- Molecular Biology
- Biochemistry
Background:
- Excitation-contraction coupling is crucial for skeletal muscle function.
- Contractile activity influences the phenotype of skeletal muscle.
- Sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) is vital for muscle relaxation.
Purpose of the Study:
- To investigate how denervation affects SERCA expression in different skeletal muscle types.
- To understand the impact of altered SERCA on muscle contractile properties.
- To analyze changes in excitation-contraction coupling following nerve injury.
Main Methods:
- Sciatic nerve transection in rats.
- Measurement of muscle mass, mRNA, and protein expression of SERCA isoforms (SERCA1 and SERCA2a).
- Assessment of contractile parameters including twitch contraction time and tension development.
Main Results:
- Denervation led to a significant decrease in muscle mass in both soleus (slow-twitch) and EDL (fast-twitch) muscles.
- Reduced expression of SERCA2a in soleus and SERCA1 in EDL muscles was observed.
- Prolonged contraction times and slowed tension development indicated impaired calcium handling.
Conclusions:
- Denervation alters skeletal muscle phenotype by affecting SERCA expression and calcium handling.
- These changes in excitation-contraction coupling are specific to muscle fiber type.
- The findings contrast with effects of biomechanical unloading on muscle.