We do extracellular and patch clamp recordings using three
different rigs. People who are new to the field might find it useful to
see, which equipment can be used for these recording techniques. One should
consider, however, that electrophysiological setups are steadily under
construction, so that a list of the equipment used can be no more than
a snapshot. The links to the manufacturers might help, if someone wants
to install his own setup. This page focuses on the equipment we use. Other
manufacturers can be found on the Links
and Addresses page.
For patch clamp recordings we use an Axopatch-1D
and an Axopatch 200
B from Axon Instruments. These devices
offer a sophisticated electronic design and are well-suited for single
channel and whole cell recordings. They provide a lot of features, some
of which are a little tricky to use, however. You should make sure the
amplifier really does what you think you told it to, e.g. if you use Track
together with an external pulse generator or a software seal test.
Tip recordings generally could be performed using every intracellular recording amplifier. Most of these
devices do not provide a sufficiently high amplification (about 200 fold),
however. We use a relatively old device, which once was custom-built by
an electronic workshop, probably in Munich. Similar amplifiers are used
in the Max-Planck-Institut für
Verhaltensphysiologie in Seewiesen, and can be obtained from
Conditioning and Storing the
Although we try to do as much online analysis as possible,
we generally store all data on tape additionally. It is important to be
aware that most recorders designed for audio purposes apply a high pass
filter to the recorded signals. In many DAT recorders this filter appears
to be located in the digital part of the circuitry, and therefore is not
so easy to disable. So you should make sure the irresistible offer from
the discounter can be customized accordingly. We use a two-channel DAT
recorder from Bio-Logic and an elderly
4-channel FM tape recorder from RACAL.
In order to record more experimental parameters, we are currently trying
an 8-channel DAT recorder (DSR 8/3) from O-5.
To get a quick overview over the recorded data, we use to
write the recordings on strip chart recorders. For each rig we use one
unit with four input channels each, a Gould EasyGraf, and a WindoGraf.
These chart recorders must be equipped with separate signal condtioners
for each input channel. Since the signals are conditioned elsewhere in
the pathway, the basic signal conditioner in the series (13-6615-11) meets
our requirements best.
To deal with the inverted current polarity in cell-attached-
and inside-out recordings, one of the signal conditioners was customized
Before digitizing the signals must be passed through an anti-aliasing
filter. 4- or 8-pole bessel filters are common for this purpose. The Axopatch
amplifier is equipped with an internal filter, which can also be applied
to external signals, as from the tape. We additionally use two stand-alone
filters. Frequency Devices offers
a variety of filters for many applications. We use a 900C/9L8L, which provides
many additional features. The other filter was custom-built by E.S.F.
electronic and does no more than filtering.
For A/D conversion we use Axon
Instruments Digidata 1200 and
1322A digitizers. The Digidata 1200 is no longer produced, and is outperformed by the
1322A in all categories.
Data acquisition and evaluation is done using Axon
Instruments software. AxoScope
8 comes together with the digitizer and allows basic data aquisition
we use for the extracellular recordings. Patch clamp experiments require
a more sophisticated acquisition software. We use Clampex
8 from the recently upgraded software package pCLAMP.
See the Links and Addresses
page for other manufacturers of patch clamp hard- and software.
Drug Application and Bath Solution Switchers
Small drug quantities are applied to the cells or patches
using a General Valve Picospritzer. The flow
of the drug solution is visualized by adding 0.1 - 0.5 % food dye from
the supermarket. For special purposes we use theta capillaries from Sutter (BT-150-10).
Mechanics and Micromanipulators
The extracellular recordings are done with old mechanical
manipulators. They are the kind of device that either stand anywhere in
the lab, or else cannot be obtained anywhere. Provided they are halfway
maintained, these very solidly designed manipulators should work fine for
another 30 years.
For positioning the patch clamp headstage and drug application
pipettes, we employ three XYZ units of Luigs
& Neumann Mini 25 manipulators. These electrical manipulators combine
a minimum of drift with the possibility to store, and therefore quickly
find, different pipette positions. The manipulator units are attached to
aluminium profiles (X-95) using custom clamp mounts. Profiles, mounts,
and other mechanical equipment can be obtained from Luigs
& Neumann, Newport, or Spindler
Other patch clampers prefer hydraulic micromanipulators (e.g.
attached to the microscope's object table. This can also lead to satisfying
results, provided the manipulators are properly maintained. But even with
a lot of experience, bringing a drug application pipette in place cannot
be as fast as with a microprocessor-controlled device.
All devices within the (custom-built) faraday cage are screwed
to a steel plate with M6 thread wholes, which rests on a thin layer of
cork on top of a concrete plate. Vibration isolation is achieved with inflatable
tubes of the size used for wheelbarrows. Sheets of cardboard or thick paper
separate the tubes from the concrete plate and the table the entire construction
rests on, respectively, which prolongs their lifetime considerably. Nevertheless,
they must occasionally be replaced. So it is not a bad idea to put small
wooden blocks under the corners of the concrete plate. And remember, Murphy's
Law is always with you! So have a few spare tubes ready, they are hard
to get in the late afternoon, right during the recording of the week.
Patch clamp recordings on cultured cells require an inverted
microscope. We use a Zeiss Axiovert 35
and a 135, both equipped with phase contrast optics and additional heat
filters (KG 1). The condensors are used without front lenses, to allow
easier access to the preparation. This makes it impossible to precisely
adjust the optics according to Köhler. However, since the recording
pipette distorts the surface of the bath solution, and therefore prevents
ideal conditions anyway, one soon gets used to working with sub-optimal
optics. The lamp power supplies were customized to avoid electrical interference.
Any stabilized DC power supply placed outside the Faraday cage should serve
Pipette Pullers and Electrode Glass
Those tiny things, one can spend weeks to find
Certain compounds of electrophysiological setups use to lie
in a hidden corner of a hidden drawer in every lab. But, due to Murphy's
Law, you always need one more item than there is left. And no one remembers,
where that thing was bought many many years ago. Small
Parts Inc. offers a broad variety of this kind of things, including
tubing, tube connectors, syringe needles (even blunt ones and ones made
of teflon), tools, and so on...
Cell cultures are said to be very sensitive towards metal
ions. Therefore we use quartz
syringe needles (WPI) for filling
the recording pipettes. Polyethylene tubing pulled over an alcohol flame
may serve the same purpose.
Last Update: August 2, 2001
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