Amadeus Schmidt wrote:
>
> Hans Kylberg wrote:
> >At 13:40 1999-10-06 +0200, Amadeus wrote:
> >>Possibly by additional detoxifying capacity of the liver.
> >>Coffee hasn't the equal strong effects after getting used to it.
>
> >Getting used to coffein is another thing. It's certain receptors
> >in the nervous system that get blocked by coffein, this is why
> >You feel more alert. But quite soon there will be more receptors
> >to adjust, so You need more coffee a. s. o.
>
> Yes, the alertness caused by caffein is a different thing,
> as you described with the receptors. Annother kind of
> "getting used to" as detixifying enzymes.
I don't think caffeine effect has anything to do with blocking receptors.
Caffeine deactivates the enzyme that breaks down cAMP (a second messenger),
thus effectively telling a cell that there are a lot more peptide hormones
bound to its receptors (because there is now more cAMP present within the
cell, which normally would happen when there are more hormones bound to
cell receptors). With constant use of caffeine the body lowers the amount
of affected hormones it produces, thus you are back to some semblance of
balance on a constant use of caffeine.

Ilya