THE PHYSIOLOGICAL AND METABOLIC CONSEQUENCES OF MUSCLE DENERVATION

Fundamental metabolic changes occur in muscle following damage of the nerve supply. These changes include alterations in the enzyme activiti es associated with oxidative phosphorylation and glycolysis, an altera tion in the metabolism of cAMP, changes in the sensitivity to insulin and other alterations of the handling of glucose and probably also an alteration in the metabolism of Ca2+ possibly resulting in a metabolic myopathy. There are also changes in the turnover of acetylcholine rec eptors and possibly cytoskeletal proteins such as dystrophin-related p rotein. The biochemical changes are paralleled by similar alterations in physiological parameters such as electromyographic measurements and structural changes such as those that occur at the endplate. Similar genes to those which are active during muscle cell development may be ''switched-on'' following a nerve injury. The return of these paramete rs to normal after reinnervation is variable and may be incomplete.