What lowers the potential of neurons?

Richard Norman rsnorman at mediaone.net
Mon Dec 3 08:47:47 EST 2001


On 3 Dec 2001 06:03:23 GMT, dag.stenberg at nospam.helsinki.fi wrote:

>Richard Norman <rsnorman at mediaone.net> wrote:
>> And don't even think about a synapse that actually DEcreases ion
>> permeabilities! 
>
>Well, but there are synapses that do so indirectly: an axon terminal may
>release a transmitter that binds to a postsynaptic receptor that via a
>G-protein in the membrane induces closure of a K+ channel, which is a
>depolarizing, i.e. excitatory action.
>
>Dag Stenberg

Exactly.  That makes defining just what is an "excitatory" or an
"inhibitory" synapse very complicated.  Let's see, its not the
transmitter -- ACh and NE can do either.  Its not depolarization vs
hyperpolarization -- a Cl channel can depolarize but still be
inhibitory. Its not the type of ion involved -- you have given a case
of an excitatory synapse that affects K channels.  So it is a little
tricky.  That is what makes neurobiology such fun.  That is also what
drives newcomers crazy.
 




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