Goldman-Hodgkin-Katz Equation
An equation calculating resting membrane potential considering relative membrane permeabilities (P_Na, P_K, P_Cl) and concentrations of multiple key ion species.
Governing formula
V_m = (R T / F) ln((P_Na[Na]_out + P_K[K]_out + P_Cl[Cl]_in) / (P_Na[Na]_in + P_K[K]_in + P_Cl[Cl]_out))
SI unit
mV (Membrane Potential)
In depth
Extends the single-ion Nernst equation to multi-ion systems. Because resting membrane permeability to potassium is ~40 times higher than to sodium (P_K ≫ P_Na), the resting potential rests near E_K (-70 to -90 mV).
Examples in the real world
Predicting resting cell membrane potential changes caused by extracellular hyperkalemia.