Pharmacology - alpha1 blockers and alpha2 agonists Flashcards
true or false
binding Gq causes vasoconstriction
true
causes calcium release and vasoconstriction
drugs that mimic the action of ___ or ___- have been termed sympathomimetic drugs
epinephrine or norepinephrine
alpha 1 receptors work through what GPCR?
what about alpha 2?
alpha 1 - Gq
alpha 2 - Gi
what does NE binding to alpha 1 receptors do to:
-blood vessels
-pupils
-urinary sphincter
CONTRACTS THEM
causes contraction of blood vessels (increased peripheral resistance)
dilation of pupils
contraction of sphincter, causing decreased urination
name 3 alpha 1 adrenergic blockers****
prazosin
doxasozin
terazosin
name 2 alpha 2 agonists
are they centrally acting?
yes
clonidine, methyldopa
rank the following according to their binding affinity to the alpha adrenoceptor:
-norepinephrine
-isoproterenol
-epinephrine
most - epi, then nor, least is isopoterenol
rank the following according to their affinity to bind the BETA adrenoceptor:
epinephrine
norepinephrine
isoproterenol
most - isoproterenol
epi
least is norepi
true or false
too much calcium supplementation will lead to Hypotension
FALSE
hypertension
alpha and beta adrenoceptors are what class of receptor?
GPCRs
when INACTIVE, the Gq receptor is bound to GTP or GDP?
GDP
bound to GTP when active
where are alpha 1 receptors located
the blood vessels
when the alpha 1 receptors are stimulated by epinephrine or norepinephrine, what happens??
they constrict
true or false
when stimulated, Gq coupled receptors decrease calcium release
FALSE - increase
true or false
stimulation of alpha 1 receptors by epi or norepi causes both pyloric sphincter contraction and urinary sphincter contraction
TRUE
thus decreases digestion and urination
explain how alpha 1 blockers like terazosin, prazosin, and doxazosin work in terms of blood pressure
they reduce the peripheral resistance by inhibiting constriction, and thus lower BP
true or false
prazosin, terazosin, and doxazosin are SPECIFIC for blocking alpa 1
TRUE
name some AE of alpha adrenergic blockers
postural hypotension
fluid retention
dry mouth
males cant ejaculate
first-dose effect of prazosin
syncopy (fainting) and depression
**aside from treating high blood pressure, what else can terazosin and other alpha 1 blockers treat????
BPH (benign prostatic hyperplasia)
bc they will RELAX the smooth muscle of the prostate
true or false
with other antihypertensive agents, alpha 1 blockers can cause hypotension
true
is there any DDI concern with alpha 1 blockers
yes - with other highly protein bound drugs like sulfa antibiotics, NSAIDS
alpha 2 agonists inhibit the….
sympathetic nervous system
true or false
alpha-methyldopa is a prodrug
true
alpha-methyldopa is a precursor of ___ and ___
dopamine and norepinephrine
rate limiting step to make NE
agonists binding to alpha 2 cause what
inhibitory effects (works through Gi) at presynaptic nerve terminals
inhibits sympathetic nervous system
alpha-methyldopa, and a2 agonist, is not used therapeutically now, except in…….
hypertension during pregancy
clonidine is not frequently used now whY?
bc of tolerance and withdrawal hypertension
explain the MOA of clonidine and how the BP is lowered
when synaptic NE levels rise at the presynaptic nerve ending, clonidine binds to the alpha 2 receptors IN THE BRAIN to shut down NE release through feedback inhibition
this results in decreased cardiac output and some decreased peripheral resistance, as well as potentially inhibitng renin release
true or false
clonidine increases the firing of sympathetic nerves
FALSE
decreases
clonidine binds at what specific site in the brain
the depressor site of the vasomotor center
**aside from treating hypertension, what else is clonidine/catepres used for
to help with nicotine and narcotic withdrawal symptoms
explain the MOA of methyldopa to help decrease BP
it acts as a false substitute of dopa.
this will form a FALSE norepinephrine called alpha methyl norepinephrine
thus, when this false NE binds to a2, it will NOT cause vasoconstriction like NE would
**which are true??
to lower BP you need:
-a1 agonist
-a2 agonist
-a1 blocker
-a2 blocker
alpha 2 agonist
a1 blocker
