The Nernst slope within the Association-Induction Hypothesis framework

The Goldman-Hodgkin-Katz (GHK) equation provides a quantitative description of the membrane potential, a quantity commonly ascribed to passive and active ion movements through channels and pumps in the plasma membrane. Consequently, the membrane potential is frequently viewed as a hallmark of living cells. In physiology, the Nernst equation is often treated as a simplified version of the GHK equation. The factor -eψ/zkT (z: ion valency; ψ: membrane potential), termed the Nernst slope, serves as a key marker of the Nernst equation's applicability and of cellular viability. Yet, nonliving systems can also develop potentials that exhibit the same characteristic slope, indicating that the Nernst slope is not necessarily a product of biological activity. An older, largely disregarded physiological model, the Association-Induction Hypothesis (AIH), explains membrane potential generation purely in terms of ion adsorption-desorption phenomena. Within the AIH framework, membrane potentials do not arise from ionic fluxes across the membrane but from equilibria that obey the law of mass action. In this study, we derive the Nernst slope using the AIH framework. This result suggests that the membrane potential may primarily reflect mass-action-determined equilibria rather than active physiological mechanisms.