The Electrical Constants of the Skeletal Muscle Fibres of the Stick Insect, Carausius Morosus

The electrical constants of the ventral longitudinal muscle fibres of the stick insect Carausius morosus were determined by analysing the low-frequency cable properties of the fibre using short cable theory. At 20 °C in normal Ringer the membrane conductance (Gm) was 0·32 mmho.cm’, the sarcoplasmic conductivity (Gi) was 6·69 mmho/cm and the membrane capacity (Cm) was 12·2 μF/cm2. In this solution the length constant (λ) was 2·13 mm and averaged 130% of the fibre length. Hypertonic ( × 2) Ringers had no significant effect on Gt but increased the membrane conductance by about 35%. The effect of temperature on the electrical constants was also investigated: the temperature coefficient (Q10) of Gm was 1·44 and that of Gi was 1·41. The Q10 of the membrane capacity was1 ·11.