Measurements of Gm using the classical technique. Two electrodes were inserted into the same fiber: one electrode was used for injection of square current pulses, and the other electrode penetrated the fiber at three locations (i, ii, and iii) to record the membrane voltage deflection associated with the current pulses. The steady-state amplitudes of these voltage deflections were then plotted against the distance between the electrodes and fitted to a two-parameter exponential decaying function whereby Gin and λ were obtained (Eq. 1). (A) Representative membrane potential deflections during current injections in a muscle fiber in the standard Krebs-Ringer solution. (B) A plot of the amplitude of the steady-state voltage deflection against the interelectrode distance of this fiber. The solid line illustrates the fit from which Gin and λ were extracted.
