Patch Clamp Configurations
The patch clamp technique is highly versatile and can be used in several different configurations, each with a specific purpose:
- Cell-Attached: The pipette forms a tight seal (giga-seal) with a small patch of the cell membrane, but the membrane remains intact. This configuration allows for the recording of single ion channel activity within that isolated patch.
- Inside-Out: Starting from a cell-attached configuration, the pipette is quickly retracted, excising the patch of membrane from the cell. The intracellular (cytosolic) side of the membrane is now exposed to the external bath solution, giving researchers direct access to the internal face of the ion channels.
- Whole-Cell: After forming a giga-seal, a pulse of suction is applied to the pipette, rupturing the membrane patch. This creates a low-resistance pathway into the cell’s interior, allowing for the measurement of currents across the entire cell membrane.
- Outside-Out: Similar to the inside-out configuration, but the pipette is retracted in a way that the patch of membrane reseals around the pipette tip. This configuration exposes the extracellular side of the channels to the bath solution, which is useful for studying the effects of drugs or other external ligands.