basic question

Pflieger Jean-Francois pfliegej at ERE.UMontreal.CA
Mon Sep 30 15:28:00 EST 1996


Richard Hall <hall at charon.ns.utk.edu> writes:
...
>Here's a follow-up:
>If synapses are, in fact, unidirectional, impulses moving in the
>opposite direction can not proceed beyond the synapse, but would such an
>impulse inhibit or disrupt the transmission of impulses moving in the
>other direction.  That is, what happens when an antidromic signal
>reaches a synapse?

First, synapses are not always unidirectional: a) Gap-junction are 
bidirectional (even if not equally in the two direction, and b) a large 
number of molecules which could act as retrograde messengers are now known 
(arachidonic acid, NO...), and evidence accumulates for their role as 
retrograde messengers. Second a antidromic action potential is 
(generally?) stoped by the absence of Na-voltage dependent channels in the 
body and dendrites of neurons. Third, an antidromic impulse could, 
theorically, inhibit a receptor or synaptic potential; but I don't know 
if there is proof or example for that. 

			Jean-Francois
-- 
Jean-Francois Pflieger		      "DINANZI A ME NON FUR COSE CREATE,
Universite de Montreal		       SE NON ETERNE ED IO ETERNA DURO:
Sciences Neurologiques		       LASCIATE OGNI SPERANZA, VOI CH'ENTRATE"
pfliegej at alize.ere.umontreal.ca	      (Dante, "l'Enfer, Chant III, vers 7 a 9)



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