adrenergic agents Flashcards
What kind of SM contraction motif do receptors w/ odd number subscript use
Phospholipase C, IP3, increased intracellular Ca via store-operated Ca channels
What kind of motif do receptors for Beta agonist use
Ad. cyclase activates cAMP, activates PKA(!) leading to phosphorylation of various enzymes
three ways alpha 2 inhibitory pathways work
increase K conduction, block Ca channels, inhibit ad cyclase, decreasing cAMP
beta stimulation activity of the three prototypes
iso»epi>ne
How do catecholamines affect HR? Force of contraction?
by stimulating If and Ca channels, increase SR Ca storage and Ca conductance
effect of NE on mean BP
slight increase
effect of ISO on mean bp
slight decrease
effect of epi on TPR in skin and mucosa
alpha only, increased tpr
effect of epi on TRP of liver and SKM
low dose- binds beta (more b than a) and decreases tpr. High dose- binds beta 1(^BP) then a (^TPR) then decreases as barostat affects and [epi] declines resulting in b2 activity
mydriasis can be induced by stimulating what receptors
alpha
What are the relevant Alpha 2 receptors?
heart (antagonize b1), GI, penis, CNS, pancreas
what kind of alpha receptors are in blood vessels
A2b (b=bloodvessels) which cause CONSTRICTION (same action as a1)
what does a typical dose of clonidine do? high dose?
stimulate central a2. peripheral postsynaptic a2b
clonidine suppression test
distinguishes essential htn (reduces plasma NE) from pheochromocytoma (no effect)
alpha methyl dopa: processing, use
taken in by uptake 1 and made into alpha methyl NE. alpha 2 stimulation. used for htn in pregnancy
dobutamine use
increase force of contraction only. CHF, cardiogenic shock
terbutaline
uterine relaxation during premature labor
ritodrine
only approved drug for premature labor
considerations fro salmeterol, formoteral
only use with corticosteroid
tyramine
uptake 1 then stimulates release of NE. Indirect sympathomimetic. Exhibits tachyphylaxis (depletion of NE)
how do tyramine and NE differ in response to cocaine
tyramine gives no response, NE response is amplified
how does an MAO inhibitor change NE signaling? tyramine?
it doesnt. Termination is by uptake, not degredation. potentiates tyramine b/c its not being degraded
explain toxicity of alpha 1 selective agonists
alpha 1 receptors in veins of nasal mucosa. OD can trigger histamine release and result in reactive hyperemia. Continued use->a2 vasoconstriction and damage
why is intracardiac EPI most useful
not just beta one but main benefit is form vasoconstriction
should you use dobutamine or dopamine in cardiogenic shock
use dopamine if systolic <80 and OLIGURIA
severe htn in ICU is usually treated with
levophed (NE)
effect of alpha 2 inhibition on heart, gi, corpus cavernosum, cns
increases HR, increases GI motility, increases NO (erection), stimulant
how does an nonspecific a blocker affect HR
results in tachycardia (blocks a2 on adrenergic nerve endings)
Tamulosin, alfuzosin, silodosin. uses and reasons. side effects
BPH tx. selevtive alpha1a antagonist. Get prostate relaxation w/o orthostatic HTN. Anejaculation
therapy for ED and mechanism
denafils. inhibit phosphodiesterase 5 (PDE5) which breaksdown cGMP
contraindication for propanolol
asthmatics, diabetics (masks signs of hypoglycemia)
metabolism of beta blockers
via cyp2d6
labetalol
HTN in pregnancy
