Voltage clamp

The voltage clamp operates by negative feedback. The membrane potential amplifier measures membrane voltage and sends output to the feedback amplifier; this subtracts the membrane voltage from the command voltage, which it receives from the signal generator. This signal is amplified and output is sent into the axon via the current-passing electrode.

The voltage clamp is an experimental method used by electrophysiologists to measure the ion currents through the membranes of excitable cells, such as neurons, while holding the membrane voltage at a set level.[1] A basic voltage clamp will iteratively measure the membrane potential, and then change the membrane potential (voltage) to a desired value by adding the necessary current. This "clamps" the cell membrane at a desired constant voltage, allowing the voltage clamp to record what currents are delivered. Because the currents applied to the cell must be equal to (and opposite in charge to) the current going across the cell membrane at the set voltage, the recorded currents indicate how the cell reacts to changes in membrane potential.[2] Cell membranes of excitable cells contain many different kinds of ion channels, some of which are voltage-gated. The voltage clamp allows the membrane voltage to be manipulated independently of the ionic currents, allowing the current–voltage relationships of membrane channels to be studied.[3]

  1. ^ Nowotny T, Levi R (2014). Jaeger D, Jung R (eds.). Encyclopedia of Computational Neuroscience. Springer New York. pp. 1–5. doi:10.1007/978-1-4614-7320-6_137-2. ISBN 9781461473206.
  2. ^ Cite error: The named reference Hernandez-Ochoa was invoked but never defined (see the help page).
  3. ^ Kandel ER, Schwartz JH, Jessell TM, eds. (2000). Principles of Neural Science (4th ed.). New York: McGraw-Hill. pp. 152–3. ISBN 978-0-8385-7701-1.