nm_fournier at ns.sympatico.ca
Sat Apr 3 20:23:48 EST 2004
Thank you for the citation. I will get the paper on Monday.
"BilZ0r" <BilZ0r at TAKETHISOUThotmail.com> wrote in message
news:Xns94C1871B32D4CBilZ0rhotmailcom at 188.8.131.52...
> "NMF" <nm_fournier at ns.sympatico.ca> wrote in
> news:LvEbc.27452$j57.1390681 at news20.bellglobal.com:
> > I know of the theory that you are talking about regarding the action
> > of amphetamine. You probably know more about that literature then I
> > do. One of the problems I have had with this concept is that if the
> > vesicles have become "leaky", then the vesicle must already be primed
> > and partially docked at the release sites within the active zones.
> > However, those vesicles not docked would expel their content in the
> > intracellular compartment and be basically catabolized by intrinsic
> > enzymatic activity. However, spontaneous transmitter release has been
> > observed and this concept of already primed vesicles have also been
> > experimentally verified, thus it might be possible that amphetamine
> > may interact with the probability of spontaneous transmitter released
> > from already primed vesicles.
> Well I think vesicles are supposed to become leaky because either a)
> amphetamines cause the monoamine transporter to work in reverse, or b)
> amphetamine increase vesicle pH, causing monoamines to dissociated from
> chaperone proteins, practically increasing the concentration of free
> amphetamine in the vesicle, which alters the equilibrium accociated with
> the monoamine transporter so that now it works in reverse.
> The theory I've read about that I like that amphetamines cause calcium to
> leak from vesicles to such a degree that it causes exocytosis. At the
> same time the also do theory b) above. So you get a little bit of
> leaking, and a little bit of exocytosis.
> > But can't amphetamine also intefere with the reuptake mechanism of
> > various monoamines? Also doesn't amphetamine lack a hydroxyl group in
> > its ring structure and possesses a isopropylamine instead of
> > ethylamine side chain? I was under the assumption that these chemical
> > differences from other sympathomimetic amines allowed amphetamine not
> > to be destroyed by enzymes that normally affect noradrenaline? It's
> > an interesting theory, I just don't know of any evidence that
> > reserpine can trigger transmitter release in a manner that you have
> > asked which would be similar to amphetamine. If you find evidence
> > please post a response on it.
> There is:
> Mundorf ML, Troyer KP, Hochstetler SE, Near JA, Wightman RM.
> Vesicular Ca(2+) participates in the catalysis of exocytosis.
> J Biol Chem. 2000 Mar 31;275(13):9136-42.
> Which is a rather horriblely presented paper, but still has some
> interesting bits in it. They used resperine to show that it decreases
> catecholamine release induced by nicotine... and if you look at the
> graph, its a histrograph of spikes per second over time... when they put
> in the resperpine, it does kinda look like it causes catecholamine
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