A three-phase multi-species electro-chemo-mechanical model of articular cartilage was developed in a companion paper, Loret and Simões (in Biomech Model Mechanobiol, in press, DOI 10.1007/s10237-004-0062-7). The model can handle mechanical and chemical loadings and unloadings involving the two salts, NaCl and CaCl2. In order to reproduce experimental data, the shielding effects are made cation-dependent. In a tensile experiment, at constant axial strain, refreshment of the bath in contact with the cartilage is observed, and simulated, to induce a much different increase in tension depending on the order of the chemical sequence to which the cartilage is exposed. For example, the sequence dw (distilled water)–NaCl–dw–CaCl2–dw results in a decrease in tension. But the initial tension is recovered if the chemical sequence is pursued by NaCl–dw. Therefore, ionic replacements are essentially reversible, as evidenced when the chemical loading events respect a certain symmetry. Distinct shielding effects by cations sodium and calcium stem from two main features: (1) different free enthalpies of formation that represent different affinities of the proteoglycans for these ions and that result in an equilibrium constant not equal to 1; (2) distinct valences but approximately the same diameter, which results in a more efficient shielding by cations calcium. The model accounts also: (1) for the anisotropy of the mechanical properties that are due to the strong orientation of collagen fibers; (2) for large deformations that occur during uniaxial traction with deionized water.