Patch clamp techniques for single channel and whole-cell recording

The patch clamp technique was first used by Neher and Sakmann (1976) to resolve currents through single acetylcholine-activated channels in cell-attached patches of membrane of frog skeletal muscle. The method they used (described by Neher, Sakmann & Steinbach, 1978) and subsequent refinements (Hamill, Marty, Neher, Sakmann & Sigworth, 1981) have led to techniques for high resolution recording of current in excised membrane patches in addition to those that remain cell-attached. Single channel recording yields information about unitary conductance and kinetic behaviour of ionic channels already partly investigated by classical voltage clamping and by noise analysis; it is also leading to the discovery of new classes of ion channel. Together with the method of whole-cell recording, which permits the application of voltage clamping to cells that are too small for microelectrode methods, patch clamp techniques also permit investigations of the physiological role of ionic channels in cells otherwise inaccessible to voltage clamp and to cells that are not electrically excitable.