Nernst slope and the constant surface charge density behind the ion adsorption-origin membrane potential

Although continuous mobile ion passage across the plasma membrane is responsible for the generation of the membrane potential, some experiments suggest that the membrane potential can be generated even without the ion passage across the membrane. This potential could be due to the ion adsorption–desorption phenomenon, and it is even possible to derive a potential formula under such a mechanism. This potential formula is somehow identical to the well-known Nernst equation. We investigated this potential formula in depth and found that the profile of “the membrane surface potential versus the logarithm of ion concentration” exhibits the Nernst slope, and this Nernst slope is the key to the identical potential formula to the Nernst equation even for the system without the passage of ions across the membrane. This work may trigger new information about the membrane potential generation mechanism. [Display omitted] •Nonzero membrane potential can be generated even across the impermeable membrane.•Nernst slope indicates the constant surface charge density of membrane.•The constant membrane surface charge density causes the ion adsorption-origin membrane potential.