Mg2+ for synaptic Isoloation of leech Neurons

Tobias Rose TRose at t-online.de
Sun Feb 18 11:42:47 EST 2001


Hi!

I'm trying to isolate my leech neurons (Retzius) from synaptic input by
using High Mg2+ (20mM) Ringer fluid.
My question: What is the exact explanation for the achieved PSP depression?
Is it just a competitive effect of Mg2+ instead of Ca2+ running through the
presynaptic Ca2+ channels and thus preventing the intracellular vesicle
exocytosis because of the absence of appropriate binding sites? Or am I
missing something?

Addtitional: To achieve te same (and some other) effects I'm using
lowCa2+/EGTA Ringer. Does anyone know a URL where I can find a table of
binding rates, affinity constants etc.  for EGTA/Ca2+ to calculate the exact
concentration of remaining free Ca2+?

And last: Is there anyone out there experienced in pharmacological effects
on leech neurons? I'm looking for some methodical knowledge exchange...

best regards,
Tobias






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