paralytic agents, Urethane- advice sought

Bill Skaggs bill at
Sun Dec 3 12:52:32 EST 1995

greggt at (Thomas R. Gregg) writes:

   > Please reply via email.  Thank you.

I am posting because your questions may be of interest to other

   > 2 projects in our lab:
   > 1) recording cortical auditory evoked potentials.  We want to
   > record from awake rats, but we need to keep them very still, to
   > avoid changes in stimulus volume (etc.) as the rats move.  We
   > want to find a paralytic drug (such as Flaxedil, curare,
   > methocarbamol) which does not cross blood-brain barrier, that
   > will reduce the rat's movements but not increase its
   > stress/arousal level.  Would methocarbamol be good for this? 
   > References are appreciated. 

You might want to check with your institutional animal care committee
before you go any further.  My understanding is that protocols
involving total paralysis of conscious animals are rarely if ever
approved nowadays.  In any case, there are good reasons to expect that
paralysis itself would cause changes in cortical evoked potentials.
If you're worried about stimulus volume, you might try using
headphones or a hearing aid.

   > 2)  recording rat hippocampal AEPs.  any problems with using
   > urethane anesthetic?  

Yes, in my experience urethane causes dramatic changes in hippocampal
activity patterns.  It greatly reduces the activity of CA1 pyramidal
cells, and I would bet that it has strong effects elsewhere as well.
I would be suspicious of any generalization from the urethane state to
the conscious state, without additional data to back it up.

	-- Bill

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