Comparison between single-pulse experimental data and radial cable model predictions. (A) Di-8-ANEPPS transients recorded in response to −120, −80, −40, 0, 40, and 80-mV pulses from VH = −20 mV (black, red, blue, green, dark blue, and orange traces, respectively). The deconvolution of ΔF/F (left vertical axis) into membrane potential (right vertical axis) was done according to the regression formula Vm = (ΔF/F − 0.016)/6.93 x 10−4 (in mV). (B) Model predictions of the TTS membrane potential assuming equal chloride permeability density in the TTS and surface membranes and the geometrical parameters of the fiber (see below). (C) Model predictions of the TTS membrane potentials assuming that ICl is located only in the surface membrane. (D) Experimental ionic currents corresponding to the optical records in A. E and F are the predicted ionic currents associated with the simulated traces in B and C, respectively. Fiber parameters: radius = 24 μm; length = 360 μm; capacitance: 6.4 μF/cm2.
