How do you calculate voltage using Nernst equation?

The Nernst equation is E = ((-2.3RT)/zF)*(log10 [Ci/Co])

E = equilibrium potential (mV)

z = charge on the ion

(2.3RT)/F = constant (60mV at 37C)

Ci = intracellular concentration

Co = extracellular concentration

The Nernst equation is important because it shows what the equilibrium potential would be for one ion.

E.g. The resting membrane potential is normally ~70mV. So during an action potential Na channels open their gates briefly and Na rush inside the cell. Na is ionized and carries a positive charge. So when Na rushes into the cell it makes the inside of the cell more positive. If you were to break off the gate and allow Na to move freely back and forth, the Nernst equation shows us that the equilibrium point for Na is ~+65mV.

•deltaG - DG0 = R T ln Q

• deltaG = nFE

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•E = E0+ (RT / nF) ln Q