Chapter 10: Adrenergics Flashcards
What are the catecholamines?
Norepinephrine, Epinephrine, Dopamine
What is VMAT?
Vesicular MonoAmine Transporter (1 = peripheral, 2 = CNS): a catecholamine/H+ antiporter
Catecholamine pathway of synthesis
Tyrosine --(tyrosine hydrolase)--> L-DOPA --Aromatic L-AA decarboxylase--> Dopamine --(Dopamine beta-hydroxylase)--> NE
2 enzymes of norepinephrine metabolism, and final product
COMT (liver cytosol) and MAO (neuron mitochondria)
***both lead to VMA, a metabolite in urine
Which receptors, alpha1, alpha2, beta1, or beta2, are presynaptic and regulate feedback inhibition of sympathetic transmission?
alpha2
alpha1 receptor: signaling mediatior + overall effects
- Gq (PLC)/Go/Gi,
- contraction of heart(BP), Urogenital, vessels, liver breakdown,
relaxation of GI
alpha2 receptor: signaling mediatior + overall effects
- Gi (decrease cAMP), Go ( dec Ca+2),
- vessel contraction,
“slow stuff down”: platelet aggregation, decreased insulin and NE release
beta1 receptor: signaling mediatior + overall effects
- Gs (increase cAMP),
contraction of heart (BP, HR), increase renin
beta2 receptor: signaling mediatior + overall effects
- Gs (increase cAMP),
relaxation of bronchial and GI smooth muscle,
skeletal muscle and liver breakdown
beta3 receptor: signaling mediatior + overall effects
- Gs (increase cAMP),
lipolysis of adipose tissue
Epinephrine has agonist effects on what receptors?
What does it treat?
beta1 and beta2 at low conc, alpha1 at high conc
beta2 = bronchial, so decreases diastolic BP and treats anaphylaxis
Norepinephrine has agonist effects on what receptors?
What does it treat?
alpha1 and beta1
increases systolic & diastolic BP, TPR, treating shock
Dopamine has agonist effects on what receptors?
What does it treat?
Low doses on D1, high dose on beta1 (heart contractility), highest dose on alpha1 (vasoconstriction)
-trearts shock
What drug is used to treat pheochromocytoma-associated HTN by inhibiting tyrosine hydroxylase?
alpha-methyltyrosine
What treats HTN(but is mostly used experimentally) by irreversibly inhibiting VMAT and can lead to a bad side effect of psychotic depression?
reserpine
What treats HTN by getting transported by NET and concentrating in the transmitter vesicles and displacing norepinephrine, leading to its depletion? This also has a side effect of postural hypotension.
guanethidine, guanadrel