Kinetics of DNQX and bicuculline?
jonesmat at physiology.wisc.edu
Mon Jul 12 15:52:37 EST 2004
tehgabriel at web.de (tomte) wrote in message news:<1adcf6cc.0407060340.4589c785 at posting.google.com>...
> I want to do a set of patch-clamp experiments with combined blockade
> of synaptic AMPA and GABA currents. For experimental reasons I'll have
> to do all recordings within a timespace of only a few minutes (5' up
> to max 10').
> Because I have rather few experience with DNQX/bic. I find it hard to
> forecast if this plan is feasible. So here is my question:
> How long does it take until DNQX and bicuculline respectively reach
> their full effect on synaptic transmission? And following wash-out:
> how long does it take until their effect is attenuated in such a
> degree that synaptic activity may be comparable to the control
> situation before application of blockers?
> Every comment is grateful appreciated!
Most of the time spent waiting for these drugs to wash in and out
comes from the time required to exchange the solutions, not from the
binding/unbinding kinetics of the drug at the receptor. For example,
if using a "fast-perfusion" system, the wash-in and wash-out times
will be of order tens of milliseconds (assuming about 10-50 uM drug).
If using bath exchange on a dish of cultured neurons, both times will
probably be of order a few tens of seconds to a few minutes.
In slices, it takes us about 5 minutes to achieve full effect of DNQX
(5-50 uM) or bicuculline (1-50 uM), and both drugs require 5-10
minutes or more of washout before control response amplitudes come
back. Our slice chamber holds about 500 ul, and we run the flow at
about 2 ml per minute.
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