Driving force (DF) refers to the force that determines the movement of ions across a membrane. It is calculated using the electrochemical driving force equation:
Driving force = Membrane potential − Equilibrium potential
Interpretation:
• If DF is positive, a positively charged ion (e.g., Na⁺, K⁺) will move out of the cell and a negatively charged ion (e.g., Cl⁻) will move into the cell.
• If DF is negative, a positively charged ion will move into the cell, and a negatively charged ion will move out of the cell.
• If DF = 0, the ion is at equilibrium, and there is no net movement.