This page is, for the most part, my notes on Chapter 3, "Ionic Basis of the Resting Potential" in From Neuron to Brain by Nicholls, Martin and Wallace.
This formula is used to calculate the equilibrium potential required to balance a ion concentration difference across a membrane.
R T Extra_Con_i
E = ----- ln( ------------- )
i z F Intra_Con_i
The Variable Definitions
RT/F is defined in units of volts and
- Ei : The equilibrium potential for the ion i.
- R : the thermodynamic gas constant
- T : the absolute temperature
- z : the charge/valence of the ion
- F : the Faraday (96485.309 C/mol)
- Extra_Con_i : the extracellular concentration of the ion i.
- Intra_Con_i : the intracellular concentration of the ion i.
= about 25 mV at room temperature/20 degrees Celsius in log e units
= about 58 mV at room temperature/20 degrees Celsius in log 10 units
= about 61 mV at mammalian body temperature/37 degrees Celsius in log 10 units
Note that RT/Fz can be easily calculated by dividing by the ion's charge.
Back to Models and Math
Back to general retina list
visit(s) to this page.
© 1995 Lance Hahn (email@example.com)