Effect of immobilization by plastering on the level of various energy metabolites in skeletal muscle.

The effect of 1 to 6-week limb immobilization by plaster fixation and the resulting skeletal muscle inactivity-atrophy was studied by analysing isotachophoretically the ATP, ADP, AMP, CrP, NAD+ and Pi content of the slow-oxidative soleus, and the fast-glycolytic gastrocnemius muscle of the rabbit. ATP and CrP levels were higher in the glycolytic while NAD+ content was higher in the oxidative skeletal muscle under normal conditions. Energy homeostasis of the muscles disturbed during the first week of immobilization, and subsequently it is adapted to the inactivity by reaching a new steady state at lower energy levels. This new level as characterized by the high energy phosphate content shows no significant difference between the two muscle types.