The
Goldman–Hodgkin–Katz flux equation (or GHK flux equation or GHK current density equation) describes the ionic
flux across a
cell membrane as a function of the
transmembrane potential and the concentrations of the ion inside and outside of the cell. Since both the voltage and the concentration gradients influence the movement of ions, this process is a simplified version of
electrodiffusion. Electrodiffusion is most accurately defined by the
Nernst–Planck equation and the GHK flux equation is a solution to the Nernst–Planck equation with the assumptions listed below.