Alterations in contractile properties and expression of myofibrillar proteins in wobbler mouse muscles

Exp Neurol. 2000 Apr;162(2):311-20. doi: 10.1006/exnr.1999.7349.


The purpose of this study was to characterize the alterations in muscle contractile (tension-pCa relationship) and biochemical (myosin heavy and light chains, troponin C content) properties in a hereditary motoneuron disease. The study was performed on wobbler mouse mutants which presented a neuronal degeneration. The time course of the disease was followed at 5 and 7 weeks in sternocleidomastoid (SCM) and soleus muscles. The wobbler disease was found to induce a shift from fast to slow myosin heavy-chain isoform expression in SCM and soleus muscles. The analysis of the myosin light-chain (MLC) composition revealed, for the SCM muscles, the appearance of the slow isoforms at 5 weeks and an increase in the regulatory MLC2 content at 7 weeks. A significant increase in the slow troponin C isoform content was found in both types of wobbler muscles at 7 weeks. The wobbler soleus and SCM muscles presented an age- and fiber-type-related atrophy, characterized by a decline in absolute maximal tension and fiber diameter. A decrease in calcium sensitivity was observed at 7 weeks for the soleus fibers and at both 5 and 7 weeks for the SCM. The results indicated fast-to-slow changes in contractile and biochemical properties of the wobbler soleus and SCM muscles, which occurred during the motoneuron degeneration process previously described in the wobbler pathology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • In Vitro Techniques
  • Mice
  • Mice, Inbred C57BL
  • Mice, Neurologic Mutants
  • Motor Neuron Disease / metabolism
  • Motor Neuron Disease / pathology
  • Motor Neuron Disease / physiopathology*
  • Muscle Contraction*
  • Muscle Fibers, Fast-Twitch / metabolism
  • Muscle Fibers, Fast-Twitch / pathology
  • Muscle Fibers, Slow-Twitch / metabolism
  • Muscle Fibers, Slow-Twitch / pathology
  • Muscle, Skeletal / metabolism*
  • Muscle, Skeletal / pathology
  • Myofibrils / metabolism*
  • Myosin Heavy Chains / biosynthesis
  • Myosin Light Chains / biosynthesis
  • Protein Isoforms / biosynthesis
  • Troponin C / biosynthesis


  • Myosin Light Chains
  • Protein Isoforms
  • Troponin C
  • Myosin Heavy Chains
  • Calcium