Biological Membranes - A. N. Ogurtsov 2012

Electrogenesis of Biomembranes
Electrical Potentials of Biomembranes
Goldman Equation

Table 5 presents the Membrane Potential values calculated using the Nernst equation for various Cells and ions, alongside the experimentally obtained Resting Potential values for these cells, φeM. Comparing the calculated and experimental membrane potential values reveals that the resting potential is closest to the potential calculated via the Nernst equation for potassium ions.

At the same time, a significant discrepancy between the experimental and theoretical values is noteworthy. This discrepancy arises because the membrane permeability to other ions was not taken into account.

Simultaneous diffusion of K+, Na+, and Cl- ions through the membrane is described by the Goldman equation:

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where РК, РNa, РСl are the membrane permeabilities for the respective ions.

At rest, РK ≫ PNa, РK > РСl. For instance, in a squid axon

Let us rewrite the Goldman equation as

When the membrane permeability to sodium and chloride ions is significantly lower than that to potassium (РK ≫ PNa, РK ≫ РCl), the Goldman equation simplifies to the Nernst equation for the resting membrane potential:

Thus, the Nernst equation is a special case of the Goldman equation under the condition that РK ≫ (PNa, PCl).



Last update: 13/08/2026

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