inthemist wrote:
2
Amphetamine indirectly induces release of NE
this is how id say it
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| HILFIGER
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Agree
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| spjokes
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Amphetamine acts by releasing NE stored in the adrenergic nerve endings in CNS
(pre synapse).
Laurence p 349 (e- 8)
my old (9) edition G&G tells the same.
But Kaplan notes gives more details that it is released from the mobile pool (not the vesicle) but the cytoplasmic NE.
There is only a limited amount of NE in this mobile pool. Therefore, tachyphylaxis to the sympathomimetic actions of amphetamine can develop. Amphetamine can also block the reuptake of norepinephrine.
SO BOTH 1 AND 2 ARE CORRECT TO MY UNDERSTANDING.
PLEASE CORRECT ME IF I AM WRONG
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| drpkaur
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Amphetamines release stores of norepinephrine and dopamine from nerve endings by converting the respective molecular transporters into open channels. Amphetamine also releases stores of serotonin from synaptic vesicles. Like methylphenidate (Ritalin), amphetamines also prevent the monoamine transporters for dopamine and norepinephrine from recycling them (called reuptake inhibition), which leads to increased amounts of dopamine and norepinephrine in synaptic clefts.
These combined effects rapidly increase the concentrations of the respective neurotransmitters in the synaptic cleft, which promotes nerve impulse transmission in neurons that have those receptors.
but it also causes release of NE from mobile pool...so i think both are right...
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| robin082006
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1. displace Norepi from the mobile pool--> Ephedrine
2. stimulate its release from the nerve terminal--> Amphetamine
Edited by robin082006 on 06/18/06 - 02:11 PM
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| alexaE
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I'd go with the first, mobile pool ...
but i also think both are somehow correct, however
kaplan doesnt say anything about the vesicle release by amphetamine, nor does lippincott if i can remember correctly- though im not sure about lippincotts
but my choice would be the 1st
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| DrVirgo
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I asked this question because in kap it says Ephedrine, Amphetamine and Tyramine ALL displace NE from the mobile pool, whereas in FA there is a picture of the nerve terminal and Amphetamines stimulating release from the nerve (or at least thats what it looks like)... so which one is it? or is it both????
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| rman
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Does "mobile pool" refer to free neurotransmitters (ie, not bound by vesicles) floating around in the cytoplasm?
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| DrVirgo
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rman: yes.
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