Comments And Recommendations - Warner OC-725C User Manual

Comments and Recommendations

In addition to mechanical isolation, the setup must also be isolated from external
electrical noise sources. These include motors, lamps, and wiring. The platform should
be shielded from these sources of electrostatic radiation with a Faraday cage. All
equipment within the Faraday cage should be grounded to the rear panel instrument
circuit ground and is best achieved by connecting everything (including the cage) to a
ground bus within the cage. Then only one wire is run from the setup to the instrument
ground.
You will need to mount the voltage recording electrode headstage and the current
injecting electrode on micro-manipulators. They need not be hydraulically driven but
such drives will minimize the damage to the cell during and after penetration, and will
make for better seals around the electrodes. Another advantage gained by reducing
membrane damage by electrodes is to enhance the possibility of making subsequent
recordings from the same cell. These suggestions are also important for minimizing
mechanical noise in the recorded data
You will need a dissecting scope for viewing the placement of the electrodes. Anything
more powerful than 40x will just get in the way. The light source for your scope should
be DC and may need to be IR and UV filtered if you plan to use it during recording.
Minimally, the recording chamber can be a stable surface on which the oocyte will not
roll around. A disposable petri dish with a piece of nylon mesh on the bottom has been
successfully used for this purpose. The dish can be stabilized by a holder or by some
wax placed around its perimeter. The diameter of the dish needs to be large enough
to accommodate the oocyte and the two bath electrodes. The walls of the recording
chamber should be low enough to not interfere with electrode placement. Perfusion of
the chamber can be accomplished using a gravity fed system. Perfusate from the dish
can be evacuated using gentle vacuum. Use as small an aperture as possible to avoid
disturbing the surface of the perfusate in the dish.
NOTE: Specialized equipment suitable for oocyte studies (oocyte
chambers, perfusion systems, a Faraday cage, a noise-free DC lamp,
and micro-manipulators) are available from Warner Instruments.
Although it is not required, a computer can be employed to control the command
voltage. Acquisition and display of data is also usually handled by computer. The OC-
725C is fully compatible with all commercially available software packages designed for
electrophysiological research.
Finally, a microelectrode puller is necessary for making appropriately sized voltage and
current electrodes. Usually, the microinjection pipette puller can also be used to make
microelectrodes. You will need use of a microscope to break off the pipette tips.
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