Computational simulation of the intracellular pressure response to action potentials using the permeation flux model for multicomponent electrolyte solutions

Action potentials on axons are caused by the permeation of sodium and potassium ions through each ion channel, and water molecules also pass through the channels with ions. Although the Hodgkin-Huxley model[1] explains the electric properties of the axon membrane associated with the permeation of ions, their model neglects the effect of water permeation flux on the transport phenomena. Thus, this study develops a new permeation flux model taking into account the transportations of sodium ion, potassium ion, and water. For this purpose, a novel model is proposed for the relations of each coupling permeability coefficient by focusing on the structure of the ion channel, and the proposed model is implemented into the 2-D simulation. In the simulation, the typical response of intracellular pressure to the action potential is reproduced, and the time-response profiles show reasonable agreement to the experimental results by Tasaki et al.[2]. The simulation results indicates the controllability of the pressure response by the parameter of the ratio of the molar fluxes of water and ions in the ion channel, which further suggests the possibility that the water permeation flux caused by the action potential induces the variation of the intracellular pressure. In the presentation, we show that the parameter also provides a new insight into the lag between the time developments of the action potential and the pressure response.