Adrenergic Agonist- T1 Flashcards
alpha1- adrenergic selective agonist
phenylephrine
alpha2- adrenergic selective agonist
- clonidine
- brimonidine
- tizanidine
- alpha-methyldopa
sympathomimetic amines (4)
- addy
- methylphen
- focalin
- vyvanse
alpha adrenergic (subtype non-selective)
- oxymetazoline–> afrin
- naphazoline–> visine
beta2- adrenergic selective agonist
- albuterol
- salmeterol–> advair
- Levalbuterol
sympathetic potency at alpha receptor
epi>norepi> isoproterenol
sympathetic potency at beta receptor
isoproterenol > epi > norepi
alpha receptors tend to
restrict
beta receptors tend to
relax, except at the heart where they constrict the cardiac muscle.
signal transduction for beta-adrenoceptor: beta receptors are coupled to…
adenylyl cyclase activation–> increase in cAMP helps to mediate cardiac cells
signal transduction for beta-adrenoceptor: alpha2 receptors are…
inhibitory on beta receptors if they are found in the same location. coupled to GI and tend to inhibit adenylyl cyclase synthesis. act like muscarinic M2 receptor which oppose beta receptors and slow HR by not allowing cAMP to be produced.
beta-adrenoceptor regulation of cardiac chronotropy (HR) and isotropy(contraction): PKA-
phosphorylates voltage-dependent Ca channel and the SR Ca-ATPase. calcium influx and depolarization which increases constriction and HR. Sarcoplasm Ca-ATPase increases calcium storage. Ca coming in from the outside is a trigger for Ca release from the SR.
beta-adrenoceptor regulation of smooth muscle relaxation. PKA phosphorylates
plasma membrane and Sr-Ca-ATPase to decrease inctracellular Ca.
signaling system for alpha1-adrenoceptor mediated effects
phosphoinositide hydrolysis and Ca mobilization. when you get more IP3, you get more Ca, which results in increase contraction.
mobilization of intracellular Ca in smooth muscle: contraction via activation of MLCK
ca released in sooth muscle binds to calmodulin and then the calmodulin activates MLCK.
MLCK phosphorylates…
light chain of myosin heads and increases affinity of myosin for actin once it phosphorylates myosin head.
mobilization of intracellular Ca in smooth muscle: alpha2 adrenoceptor in vascular smooth muscle may use coupling to
ROCs to produce smooth muscle contraction:
-presynaptically, alpha receptors are inhibitory and don’t allow norepi release.
effect of adrenergic agonist on cardiac parameters: phenylephrine
infusion of phenylephrine produces vasoconstriction and reflex decrease in HR. has affinity for alpha1 receptors. increase in MBP and decrease HR
effect of adrenergic agonist on cardiac parameters: isoproterenol
infusion of isoproterenol produces dramatic vasodilation and increase in HR with decrease in BP. affinity for beta receptors and decrease in MBP and increase in HR
effect of adrenergic agonist on cardiac parameters: epi
slow infusion of epi results in vasodilation and increase HR with little change in MBP. has affinity for alpha and beta receptors.
oxymetazoline is what receptor selective
alpha receptor selective. but doesn’t select between alpha subtypes.
brimonidine is a
alpha2 adrenergic agonist for open angle glaucoma. beta2 receptor increases aq humor and alpha2 receptor decreases aq humor.
