Hyperpolarization of Neurons

Fred Livingston livingst at pharm.med.upenn.edu
Mon May 2 19:55:56 EST 1994


In article <jstream-020594151513 at 129.106.4.46>,
jstream at girch1.med.uth.tmc.edu (Rifle River) wrote:
> 
 
> I never thought of this.  That's a valuable two cents you added.
> 
> One question though, why a wicked increase?  Is there such a thing as a
> non-wicked increase?  Or, were you merely emphasizing the point that the
> permeability for Cl- would have to be very high? 
> 


I suppose it depends on the amount of excitatory input the post synaptic
cell is receiving. If the poostsynaptic cell receives, let us just say 8
excitatory inputs at the same time, then a large Cl conductance may be
required for inhibition. However, say the cell receives two excitatory
inputs,let us say the minimum for an action potential, then a small Cl
conductance may be enough to inhibit. (One may refer to pages 160-162 of
Kandel et. al, Principles of Neuroscience.)

 At the single channel level, in reference to fast inhibitory synapses,
GABA induces the opening of GABA(A) channels. Alcohol, benzodiazepines
(increasing the number of open channels), and barbituates (increasing burst
time) are all strong potentiators of GABA(A) channels. A nice review and a
list of references can be found in Ionic Channels of Excitable Membranes by
Bertil Hille.

																											-Fred Livingston



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