Nernst equation
Definition:
An equation used to calculate the equilibrium potential (
Veq.) of an ion. The equilibrium potential for an ion is also referred to as the Nernst potential for that ion. It is the membrane potential at which no net movement of the ion in question occurs across the membrane.

where
Veq. is the equilibrium potential,
R is the
universal gas constant,
T is the temperature in Kelvin,
z is the valence of the ionic species,
F is the
Faraday's constant, and [
X]
o and [
X]
i are the extracellular and intracellular, respectively, concentrations of the ion in question.
See also:
Resting Membrane Potential - Nernst Equilibrium PotentialDerivation of the Nernst Equation
Posted: Monday, March 3, 2014
Last updated: Wednesday, March 12, 2025