How to Calculate Action Potential

Action potentials are integral in cell-to-cell communication.

An action potential is when the electrical membrane potential of a cell rises and falls over an extremely short period of time. This cellular mechanism is most commonly found in neurons and plays a vital role in cell-to-cell communication. Properly calculating the action potential of a cell network is extremely important in medicine and neuroscience research.

Things You'll Need

• Calculator

Instructions

1. Familiarize yourself with the Goldman-Hodgkin-Katz equation, also more simply known as the Goldman equation. This equation allows you to calculate the peak voltage of an action potential by using experimentally derived values for certain variables.

2. Derive for a present ion the permeability in meters per second, extracellular concentration in moles per cubic meter and the intracellular concentration in moles per cubic meter. All of these values must be collected at the peak of the action potential. If they are not collected at this time, the resulting answer will not be the true voltage of the action potential.

3. Measure the temperature, in Kelvin, at which the experiment was performed. This can simply be done by keeping a thermometer in the room while performing the experiments. If your thermometer is in Celsius, add 273 to get the temperature in Kelvin.

4. Write down the ideal gas constant and Faraday's constant. The ideal gas constant is 8.314 joules per Kelvin per mole while the Faraday's constant is 96485 coulombs per mole. These two values do not change unless the units are changed.

5. Plug all the experimentally derived values and constants into the Goldman equation. The resulting value is the membrane potential at the peak of the action potential, which is the peak voltage of the action potential.

Tips & Warnings

• All the experimentally derived values must be collected precisely at the peak of the action potential in order to properly calculate the voltage of the action potential.

• There are many calculators available online that will correctly do the math for your after inputting specific values for each variable. This is a great way to get the correct answer, but does not help you understand the mathematics behind the calculation.

References

• CSU Pomona: The Goldman-Hodgkin-Katz Equation
• World Lingo: Goldman Equation