Model of electrical conductivity of skeletal muscle based on tissue structure

Recent experiments carried out in our laboratory with the four-electrode method showed that the electrical conductivity of skeletal muscle tissue depends on the frequency of the injected current and the distance between the current electrodes. A model is proposed in order to study these effects. The model takes into account the structure of the tissue on the scale of individual fibres. It discerns three main components with respect to electrical properties: (a) extracellular medium with electrical conductivity σe; (b) intracellular medium with electrical conductivity σi; (c) muscle fibre membrane with impedance Zm. The model results show an apparent frequency dependence of the electrical conductivity of skeletal muscle tissue, as well as the way the conductivity is affected by the length the current is conducted

Intramuscular and epimuscular microstimulation of single motor units

A new epimuscular method for stimulating single motor units (m.u.'s) in free prepared muscle is described. Unit isolation is stable and can be continued for long periods. The method is compared with an intramuscular stimulation technique and histological evidence is presented to confirm the validity of both techniques