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Old 05-31-2011
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Drug Can't understand the effects of drugs working on Serotonin

I'm a little confused on the effects of serotonin and was wondering if some one could shed some light.

with carcinoid syndrome you find --> flushing, diarrhea, along with other things.

my question is this.

sumatriptan is a serotonin agonist and is used to treat cluster and migraine headache via vasoconstriction. so why is it that serotonin acts as an vasoconstrictor here and then work as a vasodilator in the face?

also, odansetron is a serotonin antagonist and its toxicity is headache and constipation. constipation makes sense but again antagonizing serotonin receptors seem to vasodilate vessels to the head?

any clarification would be greatly appreciated! thanks!
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Old 06-08-2011
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Carcinoid tumor releases many vasoactive substances, not just Serotonin, although Serotonin predominates.

Other substances that are released by carcinoid include Bradykinin and Prostaglandins (vasodilators)
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Pharmacology-, Physiology-

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