On the basis of experimental data the authors analyse some equations of mathematical biophysics in conditions of bilateral migration of ions across the plasmatic membrane and near-membrane layer--glycocalyx. Special attention is paid to the theory of the cation-exchange function of the glycocalyx in conditions of an electrolyte load.In particular, they propose the equation of change in the permeability of cations and ions on their passage through the glycocalyx (outer near-membrane layer measuring from 4 nm to 15 μm functioning as a cation exchanger): where C i (G) is the ion concentration within the glycocalyx, C i (∞) is the ion concentration in the intercellular medium, Q i (E) is the number of ions exported from the cell,Q i (I) is the number of ions imported into the cell, A i is a factor showing the adsorption capacity of the glycocalyx of the cells, R i is a factor showing the ionic lag of the potential capacity of the glycocalyx of the cell, S is the volume of the glycocalyx surrounding the cell, ΔT is the time of passage of ions through the glycocalyx.