Patch Clamp Explained (Cell-Attached, Whole Cell, Inside Out, Outside Out Configurations) | Clip

The video explains why single-channel recordings are needed to understand voltage-gated ion channel behavior. A micropipette containing aqueous solution is pressed against the neuronal membrane and suctioned to create a tight electrical seal, with a metal electrode connected to an amplifier measuring current.

The cell-attached patch clamp setup is presented as the basic configuration that directly measures current from individual ion channels in the intact cell membrane.

Retracting the micropipette while maintaining the seal removes a patch of membrane from the cell, creating the inside-out configuration that gives the experimenter control over the internal medium bathing the channels.

Increasing suction on the cell-attached patch breaks the membrane patch, allowing the pipette to access the entire cell interior and record measurements of membrane potential from the whole-cell configuration.

Retracting the micropipette from whole-cell configuration with the seal maintained causes the membrane to break and reform around the pipette tip, creating the outside-out configuration for controlling extracellular medium composition.

Using outside-out configuration with 140 mM internal and 5 mM external potassium (equilibrium potential -88 mV), the patch clamp is clamped at various voltages and microscopic currents show stochastic opening and closing behavior of individual channels.

The recorded data demonstrates that current magnitude and direction depend on driving force and conductance; clamping at equilibrium potential produces no current, while voltage changes alter the driving force and current direction accordingly.

Patch clamp recordings of voltage-gated channels reveal that potassium currents are delayed and sustained while sodium currents open rapidly and inactivate, demonstrating that macroscopic differences arise from distinct molecular structures of each channel type.