[Neuroscience] Aspiration of buffer during electrophysiology

r norman via neur-sci%40net.bio.net (by r_s_norman from _comcast.net)
Mon Aug 6 07:44:15 EST 2007


On 06 Aug 2007 09:30:30 GMT, fburton from nyx.net (Francis Burton) wrote:

>In article <mailman.532.1186371982.11350.neur-sci from net.bio.net>,
>Trevor Lewis  <t.lewis from unsw.edu.au> wrote:
>>I have a couple of tricks that I use to reduce both the electrical 
>>noise and the changes in bath solution level. Rather than use a very
>>[...]
>>With both these tricks I find that I can get away with a much less 
>>powerful suction and still get efficient solution exchange.
>
>Good advice! Another tip which may help is to use grotty glass
>tubing for suction. By 'grotty' I mean that one has allowed the
>glass to become dirty and coated with algal (or maybe bacterial)
>growth. This reduces surface tension locally and encourages a
>continuous withdrawal of solution rather than it breaking up
>into discrete 'slurps'. Obviously if cleanliness is especially
>important, you may want to avoid any extraneous source of micro-
>organisms. In my experience, however, this isn't a problem,
>presumably due to the through-flow nature of perfusion.
>
>(This tip was given to me by my PhD supervisor, Otto Hutter.)
>

That reminds me of another potential problem:  You need some kind of
vacuum line to connect to the aspiration glass actually touching the
chamber.  When this line gets "grotty" and lined with a moist coat, it
becomes a good electrical conductor and acts as a very long antenna
pulling in all sorts of noise and interference into the system, not to
mention being a capacitor storing static charge. So periodic
electrical connection of this line to your chamber will introduce all
sorts of problems.  Keep this line very short and make sure the
perfusion collection bottle is inside the shielded cage and that the
real vacuum line that leaves the cage stays clean and dry (and
electrically insulating).



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