Patchclampteknikken

Patchclampteknikken, commonly called the patch-clamp technique, is an electrophysiological method used to measure ionic currents through individual ion channels or across the whole cell membrane. The technique made it possible to record voltages and currents with high temporal and spatial resolution. It was developed in the 1970s by Erwin Neher and Bert Sakmann, whose work earned them the Nobel Prize in Physiology or Medicine in 1991.

Principle and modes: A glass micropipette, with a tip on the order of a micrometer, forms a tight seal (gigaohm seal) with a small patch of cell membrane. A low-noise amplifier controls the membrane potential or the current, enabling voltage clamp or current clamp experiments. The main configurations are cell-attached (recording current through a small patch without breaking the seal), whole-cell (rupturing the patch to access the interior), inside-out (exposed intracellular surface by withdrawing the pipette), and outside-out (extracellular surface exposed by retraction).

Applications: The method is used to study properties of single ion channels, their conductance, gating kinetics, pharmacology, and ion selectivity. It is widely used in neuroscience to investigate neuronal excitability, synaptic transmission, and ion-channelopathies, as well as in cardiology and cell physiology.

Limitations and developments: The technique requires skill and careful handling, with challenges including access resistance, series resistance, and run-time stability. It is relatively low-throughput compared with newer methods. Developments include automated patch-clamp platforms and planar patch-clamp, increasing throughput, as well as in vivo and subcellular patch-clamp adaptations.