Pflügers Archiv

, Volume 375, Issue 2, pp 219–228 | Cite as

The extracellular patch clamp: A method for resolving currents through individual open channels in biological membranes

  • Erwin Neher
  • Bert Sakmann
  • Joe Henry Steinbach
Excitable Tissues and Central Nervous Physiology


The current contributions of individual ionic channels can be measured by electrically isolating a small patch of membrane. To do this, the tip of a small pipette is brought into close contact with an enzymatically cleaned membrane of a hypersensitive amphibian or mammalian muscle fiber. Current flowing through the pipette is measured. If the pipette contains cholinergic agonist at μ-molar concentrations, square pulse current waveforms can be observed which represent the activation of individual acetylcholine-receptor channels. The square pulses have amplitudes of 1 to 3 pA and durations of 10–100 ms.

In order to obtain the necessary resolution, a delicate compromise had to be found between different experimental parameters. Pipettes with 1–3 μm internal diameter and a steep final taper had to be used, extensive enzyme treatment was necessary, and conditions had to be found in which channels open at a relatively low frequency.

Key words

Receptor Cholinergic Ionic channels Voltage clamp Membrane current Muscles 


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Copyright information

© Springer-Verlag 1978

Authors and Affiliations

  • Erwin Neher
    • 1
  • Bert Sakmann
    • 1
  • Joe Henry Steinbach
    • 2
  1. 1.Abteilungen Molekularer Systemaufbau und NeurobiologieMax-Planck-Institut für Biophysikalische ChemieGöttingenGermany
  2. 2.Neurobiology DepartmentThe Salk InstituteSan DiegoUSA

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