Editing Patch clamp (section)

=== Set-up ===
[[File:Patch Clamp Rig classic.jpg|thumb|right|Classical patch clamp setup, with [[microscope]], antivibration table, and [[micromanipulator]]s]]
During a patch clamp recording, a hollow glass tube known as a [[Pipette#Glass micropipette|micropipette]] or patch pipette filled with an electrolyte solution and a recording [[electrode]]  connected to an amplifier is brought into contact with the membrane of an [[Cell isolation|isolated cell]].  Another electrode is placed in a bath surrounding the cell or tissue as a reference [[Ground (electricity)|ground]] electrode. An electrical circuit can be formed between the recording and reference electrode with the cell of interest in between.

[[File:Pipette Puller-en.svg|thumb|left|Schematic depiction of a pipette puller device used to prepare micropipettes for patch clamp and other recordings]]
[[File:Patch clamp schematic 1.png|thumb|Circuit formed during whole-cell or perforated patch clamp]]
The solution filling the patch pipette might match the ionic composition of the bath solution, as in the case of cell-attached recording, or match the [[cytoplasm]], for whole-cell recording. The solution in the bath solution may match the physiological extracellular solution, the cytoplasm, or be entirely non-physiological, depending on the experiment to be performed. The researcher can also change the content of the bath solution (or less commonly the pipette solution) by adding ions or drugs to study the ion channels under different conditions.

Depending on what the researcher is trying to measure, the diameter of the pipette tip used may vary, but it is usually in the [[micrometre|micrometer]] range.<ref name=Bannister>{{cite book|last1=Bannister|first1=Niel|editor1-last=Langton|editor1-first=Phil|title=Essential Guide to Reading Biomedical Papers: Recognizing and Interpreting Best Practice|date=November 1, 2012|publisher=Wiley-Blackwell|isbn=9781118402184|doi=10.1002/9781118402184}}</ref> This small size is used to enclose a [[cell membrane]] surface area or "patch" that often contains just one or a few ion channel molecules.<ref name= Sakamann>{{cite journal|last1=Sakmann|first1=B.|last2=Neher|first2=E.|title=Patch clamp techniques for studying ionic channels in excitable membranes|journal=Annual Review of Physiology|date=1984|volume=46|pages=455–472|doi=10.1146/annurev.ph.46.030184.002323|pmid=6143532|hdl=21.11116/0000-0000-D552-3|hdl-access=free}}</ref> This type of electrode is distinct from the "sharp microelectrode" used to puncture cells in traditional [[Electrophysiology#Intracellular recording|intracellular recordings]], in that it is sealed onto the surface of the cell membrane, rather than inserted through it.

[[File:Patch clamp schematic 2.png|thumb|left|Typical equipment used during classical patch clamp recording]]
In some experiments, the micropipette tip is heated in a microforge to produce a smooth surface that assists in forming a high [[electrical resistance|resistance]] seal with the cell membrane. To obtain this high resistance seal, the micropipette is pressed against a cell membrane and suction is applied. A portion of the cell membrane is suctioned into the pipette, creating an [[omega]]-shaped area of membrane which, if formed properly, creates a resistance in the 10–100 [[Ohm (unit)|gigaohms]] range, called a "gigaohm seal" or "gigaseal".<ref name=Sakamann /> The high resistance of this seal makes it possible to isolate electronically the currents measured across the membrane patch with little competing [[electronic noise|noise]], as well as providing some mechanical stability to the recording.<ref>{{cite journal|last1=Sigworth|first1=Fredrick J.|last2=Neher|first2=E.|title=Single Na+ channel currents observed in cultured rat muscle cells|journal=Nature|date=October 2, 1980|volume=287|issue=5781|pages=447–449|bibcode=1980Natur.287..447S|doi=10.1038/287447a0|pmid=6253802|s2cid=4238010}}</ref>