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What are the orders of magnitude in synapses ?

elis f. stanley elis at helix.nih.gov
Sat Sep 24 03:12:20 EST 1994

In article <35mbqj$263 at vink.Univ-Angers.Fr> Nicolas Chambet writes:
>I'm looking again for some orders of magnitude on:
>   a typical number of postsynaptic receptors or channels in synapses;
>   a typical number of presynaptic vesicles activated by one AP.
>If you have any reference, thanks a lot for advance.

Your questions are hard to answer with any specificity without a location
and a context.  It sounds like you are looking for information that will
allow you to model?  If so then you probably want data restricted to the CNS?
The squid giant synapse activates 2,500 vesicles for a single action
potential whereas each bouton in the CNS (and each neuron to neron contact
may have many bouton contacts) release one or none/a.p.  Thus, your
question is impossibly broad.  Furthermore, the number of postsynaptic
receptors will tell you very little about the potential strength of a
synaptic contact since one quantum saturates its local area and much of the
transmitter goes to 'waste' (at least in cholinergic synapses). I don't
have my references handy right now but this was considered in some detail
by M. Salpeter in the early '80s (or late 70s).

Elis Stanley, Synaptic Mechanisms Section NINDS, NIH

PS last time I posted I received an E-mail from Israel.  I tried to respond
but the address did not work.  Try again!

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