in vitro nerve experiments
rsnorman at mediaone.net
Tue Apr 18 09:09:41 EST 2000
You must use a properly balanced salt solution with proper concentration
of Na, K, Ca, pH, etc and osmotic pressure. These go by different names:
Ringer, Krebs, etc. Find a materials and methods section from anybody
who works with rat nerves and use that. A paper that happens to be on hand
(P. Shrager et al, J Physiol 79:529-536(1988)) uses a "Locke" solution for
rat sciatic nerve (values in mM):
154 NaCl, 5.6 KCl, 2 CaCl2, 5.6 d-glucose, 10 HEPES pH 7.4.
Peripheral nerve is not particularly temperature sensitive (the conduction
velocity changes, but the excitability doesn't particularly) but, still,
mammalian tissue is tradionally done at 37C.
The 95%O2-5% CO2 gas mixture is necessary both to oxygenate the tissue
and to maintain the pH when a bicarbonate buffer is used. Although
mammalian tissue is normally subject to a pCO2 level of 40 mm Hg (which
corresponds to 5% of atmospheric pressure), if you use a non-bicarbonate
buffer this is not really necessary, especially on isolated peripheral
Of course, you must keep the nerve moist. If your recording technique
keeping the nerve in air, it must be in an enclosed chamber fully saturated
with water vapor.
And, of course, you must avoid overstimulation. Leave the stimulator set to
10/second for five or ten minutes while you are fussing with something and
you have just run thousands of action potentials through cells which already
are in some metabolic difficulty!
Stefan de Kool <dekool at plch.azr.nl> wrote in message
news:8dhnlp$gie$1 at nnrp1.deja.com...
> Dear anybody,
> I'm doiing in vitro measurements of compound action potentials of rat
> peripheral nerves. Can anyone tell me what is the best way to unsure the
> nerve keeps functioning upon electrical stimulation? In literature
> people use different kinds of buffer solutions and sometimes bubble
> there solutions with carbonate (95%O2,5%CO2), but it's not clear to me
> which way is the best. I'll be glad to hear anything.
> Thanks for your attention. bye
> Stefan de Kool,
> Research assistant
> Erasmus University Rotterdam
> email: dekool at plch.azr.nl
> Sent via Deja.com http://www.deja.com/
> Before you buy.
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