The ionic fluxes and capacitances simulated in the CD model of skeletal muscle cable properties. A multi-compartment model was developed to model the cable properties of skeletal muscle. The muscle fiber was divided into 99 longitudinal segments, the length of which could be varied. Each cable segment contained a t-system compartment that could be simulated as a single compartment or further subdivided into several concentric shells. In each cable segment, ionic fluxes through background and voltage-gated ion channels, calculated using the Goldman equation, and Na⁺/K⁺-ATPase (pump) fluxes were simulated across the sarcolemma membrane (J_s), and across the membrane of each t-system shell (J_n). Ionic fluxes across the t-system access resistance (J_t(e→0)), between t-system shells (J_(n→n+1)), and between adjacent cable segments of the muscle fiber (J_(l)) were calculated using an electrodiffusion equation according to the prevailing concentration and electrical gradients. In addition to the depicted ionic currents, water fluxes were also modeled, allowing the model to reach a steady state that is independent of the initial concentration of any ion. Potential differences were calculated, as described in the Theory section, across the surface membrane capacitance (C_m), across the membrane capacitance of each t-system shell (C_n), between each cable segment, between the extracellular space and the outer shell of the t-system, and between each t-system shell.