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22 Cards in this Set
- Front
- Back
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Which 5-HT receptor types are G-protein coupled receptors?
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5-HT1, 5-HT2, and 5-HT4. (5,6, and 7 are also coupled to G-protein receptors but are not well characterized).
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Which 5-HT receptoris directly activated by 5-HT.
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5-HT-3
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What is the functional mechanism of 5-HT1 receptors?
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They function as inhibitory autoreceptors by increasing K conductance. They inhibit serotonin release.
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Where are 5-HT1 receptors found?
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Raphe nuclei of the brainstem.
(5-HT1d receptors are found in the basal ganglia and they inhibit serotonin release and help regulate dopamin release) |
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What is the mechanism of 5-HT2 receptors?
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They are linked to phospholipase C transmission activating diacylglycerol and inositol triphosphate second messanger systems.
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Where are 5-HT2 receptors found?
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They are distributed throughout the CNS but are concentrated in the prefrontal cortex.
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What is the machanism of 5-HT3 receptors?
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5-HT binding causes Na influx and depolarization.
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Where are 5-HT3 receptors found?
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The parasympathetic terminals in the GI tract and the areas of the CNS invovled in the emetic response.
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Which cells in the GI tract secrete 5-HT and what is its effect?
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Enterochromaffin cells. 5-HT causes smooth muscle contraction and increased GI motility.
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Which hematologic cell stores and releases 5-HT and what is its effect?
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Platelets. Release causes vasoconstriction. Released due to tissue injury.
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What effect does 5-HT have on the heart?
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Causes an overall positive inotropic and chronotropic effect.
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Bezold-Jarisch reflex
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5-HT induced vagal tone to the heart that results in 3rd degree heart block. Seen in patients with CVD.
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Buspirone
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Antianxiety agent. 5-HT1a agonist.
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Triptans
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Antimigraine agents. Selective 5-HT1b and 1d agonists. Induce vasoconstriction of cerebral blood vessels.
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What is the prototype triptan
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Sumatryptan
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What are the toxic side effects of triptan use?
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Heart block and coronary artery spasm. Triptans are contraindicated in patients with heart disease.
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Ergots and Ergot Alkaloids
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Promiscous agonist activity at 5-HT and alpha adrenergic activity. Used to treat migraines. Constrics blood vessels in the brain.
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Toxic effects of ergots
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Cardiac valvular lesions and retroperitoneal fibroplasias.
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Lysergic Acid Diethylamide (LSD).
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Hallucinongenic agent. No therapuetic use.
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Ketanserin
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5-HT1c and HT2 receptor antagonist. used to treat hypertension.
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Ondansetron
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Antiemetic agent. Selective blocker of 5-HT3 receptors. Used to treat chemotherapy-induced emesis.
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Ritanserin
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Selective 5-HT2 receptor antagonist. In phase 3 trials to prevent thromboembolism.
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