Block 2: Serotonin and Smooth Muscle Flashcards
what is the enzyme responsible for serotonin metabolism?
monoamine oxidase
how is serotonin eliminated from the synapse? what drug inhibits this?
active reuptake, fluoxetine
where is the most serotonin found?
GI
effects of serotonin in GI (2)
causes contraction of GI smooth muscle
emesis (vomiting) can be induced by 5-HT3 receptors in brain and GI tract
effects of serotonin on CV system (3)
potent vasoconstriction of large arteries and veins (especially pulmonary and renal vessels)
vasodilation in coronary, skeletal muscle, and cutaneous vessels
platelet aggregation
fluoxetine: mechanism, therapeutic uses
SSRI, blocks active reuptake of serotonin into neurons
uses: affective disorders, OCD, panic attacks
phenelzine: mechanism, therapeutic uses, side effects
monoamine oxidase inhibitor, blocks metabolism of serotonin, norepinephrine, dopamine
uses: affective disorders, narcolepsy
side effects: hypertensive crisis
indirect agonists of serotonin
fluoxetine and phenelzine
serotonin antagonists
ondansetron and alosetron
5-HT3 receptor antagonists (2)
ondansetron and alosetron
ondansetron: mechanism, therapeutic use
5-HT3 receptor antagonist, acts both at GI and brain receptors
use: chemotherapy-induced nausea and vomiting
alosetron: mechanism, therapeutic use, side effects
5-HT3 receptor antagonist
use: diarrhea in women with IBS
side effects: severe GI effects
nitroglycerin: mechanism, preload vs afterload, therapeutic use
releases NO –> cGMP signaling, decreases preload
uses: heart failure, abort an acute attack of primary or secondary angina, prevent future angina
nitroprusside: mechanism, preload vs afterload, therapeutic use
releases nitric oxide –> cGMP signaling, decreases preload and aftterload
uses: hypertensiv emergencies, heart failure, lowers BP with little change in heart rate
name 2 direct vasodilators
hydralazine and minoxidil
hydralazine: preload vs afterload, therapeutic use
decreases afterload
uses: heart failure, hypertension
minoxidil: mechanism, preload vs afterload, therapeutic use, side effects
opens potassium channels –> hyperpolarization –> vasodilation, decreases afterload
uses: heart failure, severe hypertension
side effects: reflex tachycardia, headache, hair growth, fluid retention
diazoxide: mechanism, therapeutic uses, toxicity
opens potassium channels
uses: hypertensive emergencies, hypoglycemia
toxicity: reflex tachycardia, use with beta blocker (propranolol)
what does reflex tachycardia affect myocardial oxygen demand in what way?
reflex tachycardia –> increases myocardial oxygen demand –> angina
what drugs open potassium channels?
minoxidil and diazoxide
CCBs: mechanism, preload vs afterload, 2 drugs
decrease contraction in cardiac and vascular smooth muscle, decreases afterload, verapamil and diltiazem
name a PDE3 inhibitor
inamrinone
iamrinone: mechanism, second messenger, therapeutic use
inhibits PDE3, increases cAMP –> increased contractility in cardiac cells, relaxation in vascular smooth muscle
use: heart failure
what is the action of PDE3?
converts cAMP to AMP, preventing contraction
