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)
