Electrochemical driving force

In physiology, the electrochemical driving force for a certain ion is the difference between the membrane potential and the equilibrium potential for this ion.

Just as a voltage difference in electrical engineering determines the strength of the current through a constant resistance , so the electrochemical driving force determines the strength of the ion flow through a given number of open ion channels . The greater the electrochemical driving force, the greater the ion flow through the individual ion channel.

The membrane current carried by the ion of type i at a certain point in time depends on the membrane potential and equilibrium potential of this ion as follows: ${\displaystyle I_{i}}$ ${\displaystyle V_{m}}$ ${\displaystyle E_{i}}$

${\displaystyle I_{i}=g_{i}(V_{m}-E_{i})}$

${\displaystyle V_{m}-E_{i}}$ = electrochemical driving force for the ion i.

${\displaystyle g_{i}}$is the membrane conductivity for the ion i. It is determined by the number of open ion channels for ion i and the conductivity of a single such channel for ion i.

The electrochemical driving force not only has an amplitude , but also a direction. It is directed in such a way that when an ion channel which is specific for a certain ion is opened, the membrane potential changes in the direction of the equilibrium potential for this ion.

See also

• Electrochemical potential
• Electrochemical gradient
• Electrochemical equilibrium
• Concentration gradient