From Action Potential-Clamp to "Onion-Peeling" Technique – Recording of Ionic Currents Under Physiological Conditions

Upon stimulation, excitable cells generate a transient change in the membrane potential called Action Potential (AP). The AP is governed by numerous ionic currents that flow in or out of the cell membrane. The goal of cellular electrophysiology is to understand the role of individual ionic currents and the interplay between currents in determining the profile and the time course of AP. A critically important question of the field is how different ionic currents behave individually and interact collectively during the AP cycle in an excitable cell. To answer this question we need to know the dynamic behavior of ionic currents during AP and how these currents work in concert to determine the cell’s membrane potential at every moment.