Figure 4. Analysis of action potential waveform and resting membrane potential during activity in rat and mouse fibres.

A shows overlays of V₂ and V₃ recordings of the first action potential in the first (First AP), 20^th (1001^th AP) and the 78^th (3851^th AP) run of current injections in a representative rat EDL fibre. The shaded area in the V₃ recording indicates the part of the action potential waveform above −20 mV. B, action potential peak (AP peak) and resting membrane potential (V_m rest) measured by V₃ during the experiments using rat (n = 14) and mouse (n = 7) EDL fibres. C shows the changes in relative waveform area above −20 mV (RAA) of the first action potential recorded by V₃ in each run during the experiments as illustrated in A, together with the calculated G_m. n = 7 or 14 (mouse and rat, respectively). Plots in B and C have been shown on the same time axis displayed below C. Average data shown as mean ± SEM.