Enter the membrane potential and the ion equilibrium potential into the calculator to determine the driving force. This calculator also includes several mechanics “driving force” calculations (vehicle traction, a block on an incline, and rotational torque).
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Driving Force Formula
The following equation is used to calculate the Driving Force.
Vdf = Vm - Veq
- Where Vdf is the driving force (mV or V)
- Vm is the membrane potential (mV or V)
- Veq is the equilibrium potential (mV or V)
To calculate the electrochemical driving force using this sign convention, subtract the equilibrium potential from the membrane potential.
What is a Driving Force?
Definition:
In membrane electrophysiology, the (electrochemical) driving force for a specific ion is the difference between the membrane potential (Vm) and that ion’s equilibrium (Nernst) potential (Veq).
A larger concentration gradient of the same ion across the membrane generally makes the magnitude of its equilibrium potential larger; the driving force magnitude depends on how far Vm is from Veq.
How to Calculate Driving Force?
Example Problem:
The following example outlines the steps and information needed to calculate the Driving Force.
First, determine the membrane potential. In this example problem, the membrane potential is measured as −70 mV.
Next, determine the equilibrium potential. In this case, this is calculated to be −90 mV.
Finally, calculate the electrochemical driving force using the formula above:
Vdf = Vm – Veq
Vdf = (−70) – (−90)
Vdf = 20 mV
