Electrolytes in Denervated Muscle

Abstract

The mechanism of muscle atrophy is hitherto unknown. It is necessary to investigate the exact sequence of processes beginning with interruption of the neuromuscular connection and ending by disintegration of muscle fibres. This problem is difficult to solve. One of the first tasks is analysis of changes in various substances during the course of denervation atrophy which will provide fundamental data concerning the denervated muscle. Inorganic ions, especially sodium and potassium, belong to this class of substances characterizing the muscle tissue. Sodium and chloride ions can provide information concerning the extracellular fluid volume in muscle due to a primarily extracellular distribution (Hastings and Manery 1939). It is true that sodium ions diffuse into the cell. They are transported back into the extracellular fluid, however (see Ussing 1958, Conway 1958). Potassium, on the other hand, is retained primarily in the intracellular fluid and represents the osmotic medium of intracellular fluid, being the main intracellular ion. These ions play a very important role in muscle metabolism and its functional activity. Potassium ions can affect various enzymatic reactions in the metabolism of proteins (Iacobelis et al. 1956), carbohydrates (Hastings et al. 1956) as well as lipids (Geyer et al. 1953a, 1953b). According to Szent-Györgyi (1952) potassium ions are indispensible for maintaining myosin in colloidal state, and Hodgkin and Horowitz (1959) have shown the significance of equilibrium between K and Na ions for conduction of the electric stimulus along the muscle fibre.