Pharm 9.1 Flashcards
norepinephrin is an
adrinergic neurotransmitter (except in sweat glands)
Epinephrine is hormone secreted by
the adrenal madula
Dopamine a neurotransmitter is found in
the basal ganglia, limbic system, CTZ, and anterior pituitary
difference btw norepinephrine and epiephrine
NE is an NT secreted by neurons and does not act on beta 2 rec, Epi is a hormone secreted by adrenal medulla and acts on all recptros (low dose acts on beta rec)
Epinephrine, norepinephrine, and dopamine (catecholamines) synthesized form
tyrosine
what is the rate limiting step in the synthesis of catecholamines
tyrosine hydroxylase
Fates of NE
binds alpha 1 rec post synaptically, binds alpha 2 rec presynaptically for auto inhibition, gets metabalized by MAO in axoplasm and COMT in snapse, reuptake back into primary neuron
tyrosine to dopamine happens in
axoplasm
dopamine is stored in
vesicles to prevent degredation
dopamine to NE in
vesicles
transport of dopamien into vesicles is inhibited by
reserpine
release of NT from axon termila is caused by
influx of ca causing fusion of the vesicle with the cell membrane
release of catecholamine vesicle is blocked by
guanethidine and bretylium
reuptake of catecholamines is inhibited by
cocain and imipramine
where is dopamine beta hydroxylase
dopamine beta hydroxilase is in vesicles to convert dopamine to NE
how is Ne coverted to Epi
by PNMT (phenylethanolamine N methyltransferase) only in the adrenal medulla bc epinephrine is important in flight, fright, fight
granules take up dopamine from the
cytoplasme
conversion of dopamine to NE occurs in granules by
dopamine beta hydroxylase
where are the granules
in the adrenergic termina (NE is stored in them)
how are NE and other catecholamines released
exocytosis in response to stimulatory signal
indirectly acting amines like tyramine and amphetamines induce
release of NE by displacing it from the nerve endings
efficient mechanism of release of NE
uptake of Ca
the most important mechanism for the ermination of the NE action
axonal uptake–>i.e. reuptake
what ihibits reuptake
cocaine and imipramine
NE can bind all receptors EXCEPT
BETA 2
metabolism of NE occurs by two enzyme systmes
MAO and COMT
MAO
monoamine oxidase
COMT
catechol-O-methyl transferase
NE is acted upon by MAO in the
axoplasm
COMT acts on NE when
NE it diffuses out in circulation, mainly in the liver and in the blood stream
MAO-A is present
in the nerve/liver mainly or anywhere
MAO-A metabolizes
NE, 5HT, tyramine
MAO-A inhibitors
Phenelzine, Tyranylcypromine (antidepressants)
MAO-B is present in the
Brain
MAO-B metabolizes preferentially
dopamine
MAO-B inhibitor
Selegiline (antiparkinson)
COMT inhibitors
Tolcapone, Entacapone
Tolcapone is
long acting
Entacapone is
Short acting
major metabolites excreted in the urine are
VMA (Vanillyl mandelic acid), metanephrine, and dihydroxy mandelic acid
when do you see an increase in adrenergic metabolites
pheochromocytoma - tumor of adrenal gland
does metabolism play a significant role in the termination of action of NE?
NO
what inteferes with the synthesis of catecholamines by intefering with tyrosine hydrolase
Metyrosine
what causes a blockade of storage in granule or granular uptake of catecholamines
Reserpine
what causes Displacement of NE from vesicles
amphetamine, tyramine (indirect sympathomimetic agents)
what causes Prevention of release of catecholamines
bertylium, guanethidine
wht causes block of reuptake at nerve terminal of chatecholamines
cocaine and imipramine
adrenergic receptors
alpha beta dopamine
aplpha receptors
alpha 1 (usually post synaptic) , alpha 2 (usually pre synaptic)
beta receptors
beta 1, 2, 3
dopamine receptors
D1, D2
type of receptors that adrenergic receptors are
g-proteins coupled receptors
adrenergic receptors act by either
increasing or decreasing syn of cAMP OR through IP3, DAG, and Ca2+ as second messengers
alpha 1 is a
Gq - inc PLC –> inc IP3, DAG, Ca2+
alpha 2 is a
Gi - dec Adenylyl cyclase –> dec cAMP
beta1/2 and D1 receptors are
Gs - inc Adenylyl cyclase –> inc cAMP
alpha 1 subtypes
A B D
alpha 2 subtypes
A B C
where do you find the alpha 1 subtype
SM of urethra – use drugs targetting this recptors in obstructions in BPH
alpha 1 on
eye (radial/dialator) muscle, Arterioles (skin, viscera), Veins, Bladder trigone and sphincter, Male sex organs, Liver, Kidney
alpha 1 in eye/dialator muscle
contraction - mydriasis
alpha 1 in the arterioles (skin, viscera)
contraction - incTPR - inc diastolic pressure - inc afterload –want to shunt blood away from the skin and viscera and more available for the heart
alpha 1 in the veins
contraction - inc venous return - inc preload
alpha 1 bladder trigone and sphincter
contraction - urinary retension
alpha 1 in male sex organs
vas deferens - ejaculation
alpha 1 in liver
inc glycogenolysis
alpha 1 in kidney
dec renin release
alpha 2 receptors are found in
prejunctional nerve terminals, platelets, pancrease
alpha 2 in prejunctional never terminals
dec transmitter release and NE synthesis
alpha 2 in platelets
aggregation - makes sense bc in fight or flight you want to prevent bleeding out
alpha 2 in pancreas
dec insuline secretion
beta 1 in the
heart, Kidney
beta 1 in the SA node
inc HR - positive chronotropy
beta 1 in the AV node
inc conduction velocitiy (positive dromotropy)
beta 1 in artiral and ventricular muscle
in force of contraction (positive inotropy), conduction velocity, CO and oxygen consumption
beta 1 in His-Purkinje
inc automaticity and conduction velocity
beta 1 in Kidney
inc renin release
beta 2 in the
blood vessels, uterus, bronchioles, skeletal muscle, liver, pancres
beta 2 in the blood vessels
vasodialation - dec TPR - dec diastolic pressure - dec afterload
beta 2 in the uterus
relaxation
beta 2 in the bronchioles
dialation
beta 2 in the skeletal muscle
inc glycogenolysis - contractility (tremor)
beta 2 in the liver
inc glycogenolysis
beta 2 in the pancreas
inc insuline secretion
what receptor is most important for glycogenolysis
beta 2 then alpha 1
D1 peripheral receptor actos on
renal, mesenteric, coronary vasculature, causing vasodialation, inc renal blood flow, inc GFR, inc Na secretion(natriuresis)
slective agonist of Alpha 1 receptors - alpha 1 mimetics
phenylephrine, methoxamine
selective antagonist of alpha 1 receptors
prazosin, doxazosin, tamsulosin (on alpha 1A)
alpha 2 receptor agonsit
clonidine, guanfancine, methyldopa
alpha 2 antagonist
yohimibine
beta receptors
beta 1, 2, 3
beta 1 rec
on heart
beta 2 on
SM
beta 3 on
fat cells (adipocytes)
selective beta 1 agonist
dobutamine
slective beta 1 antagonist
atenolol, metoprolol
beta 2 receptors are mostly
not innervated
selective beta 2 agonsit
albuterol (salbutamol), salmenterol (longer acting), terbutaline
selective beta 2 antagonist
butoxamine
why would a beta 2 antaganist be used
treat bronchospasm (w/ butoxamine) bc remember beta 2 dialate, they are the enemies of alpha 1 that constrict
classification of adrenergic drugs
direct, indirect, mixed
direct actiong adrenergic drugs
epinephrine, norepinephrine, phenylephrine (beta 1), albuterol (beta 2)
indirect acting adrenergic drugs
acts by releasing NE, Tyramine, Amphetamine
Mixed acting adrenergic drugs
Ephedrine, Phenylpropanolamine (not on market bc caued stroke after it was in cough mixture)
naturally occuring catecholamines includes
epinephrine, norepinephrine, dopamine
catecholamines sturcture
catechol moiety and an ethylamine side chain
catecholamines are rapidly inactivated by
MAO and COMT (inactivation starts from the gut)
the catecholamine epinephrine acts on
alpha 1, alpha 2, beta 1, beta 2
the catecholamine norepinephrine acts on
alpha 1, alpha 2, beta 1
the catecholamine isproterenol acts on
beta 1, beta2, like epinephrine on steroides bc it vasodialates and decreases heart rate? And there is a reflex tachycardia
the catecholamine dobutamine acts on
beta 1
the catecholamine dopamine acts on
D1 ( beta 1 and alpha 1 at high doses)
the non-catecholamines that work on alpha 1 only
oxymetazolin, phenylephrine, methoxamine
non catecholamines that work on beta 2 only
albuterol, pirbuterol, terbutaline, salmeterol, formeterol
non catecholamines that acts more on beta 2 than beta 1
metaproterenol
non catecholamines that work on alpha and beta
ephedrine, psuedoephedrine
action of alpha 1 agonists
inc TPR, inc BP, potential reflex bradycardia, no change in pulse pressure
when could you use an alpha 1 agonist
tachycardia
action of beta 2 agonists
beta 1 actions increase HR, SV, CO, and pulse pressure, beta 2 actions decrease TPR and BP, overall increase/widening in pulsepressure
normal SV is
70 ml/beat
Epinephrine is a potent activator of
alpha and beta adrenergic receptors and have prominent cardiovascular effects
Epinephrine is involved in the sympathetic
fight flight fright
epinephrine on beta 1 receptors in CVS
inc rate of depolarization in cardiac myocytes, inc inotropy, inc chronotropy, inc CO, inc in BP
how does activating beta 1 receptors in CVS lead to faster depolarization
cardiac myocytes always leak out potassium, but activation of beta 1 receptors closes the potassium gates faster, depolarizing the SA-AV purkinje, increasing the rate of contraction and heart reate
when is activating beta 1 receptors important
asystole (no contraction)
epinephrine on alpha 1 receptors in CVS
at high dose causes vasoconstriction (vasopressor effect) via alpha 1, but at low does epi causes vasodialation (vasodepressor effect) via beta 2, produces a biphasic response
biphasic response
different effect based on dose
Dale’s vasomotor reversal (Epinephrine Reversal)
when alpha 1 receptors are blocked, epinephrine will produce hypotension because of unmasking of beta 2 receptor activation
low dose epiniephrine
beta 1 and beta 2 stimulation
high dose epinephrine
alpha 1, beta 1(beta2) stimulation —but beta 2 effect is masked
high dose epinephrine on alpha 1
inc TPR, inc BP, potential reflex bradycarida
high dose epinephrine on beta 1
inc HR, inc SV, inc CO, inc pulse pressure
high dose epinephrine on beta 2
dec TPR, dec BP —> masked at the high dose
epinephrine on beta 2 receptors in Respiratory system
bronchodialation
alpha 2 receptors work by
stimulating Gi path, decreasing cAMP, stimulating nitric oxide release
anaphylaxis
bronchospasm + anaphylactic shock or low BP
how is Epinephrine used in anaphylaxis
beta 2 action decreases bronchospasm increasing partial pressure of O2; alpha 1 action increases CO, systolic BP, pulse pressure, tissue perfusion; decrease in eosinophil count reducing anaphylatoxin release
Gs
increases cAMP that inhibits MLCK (myosin light chain kinase)
Epinephrine metabolic effect
hyperglycemia, lipolysis
hyperglycemia by epinephrine
inc glycogenolysis in muscle and liver (beta 2), inc in gluconeogenesis (due to inc release of glucagon -( beta 2), dec insulin secretion (alpha 2)
lipolysis by epinephrine
beta 3 - inc cAMP in adipose tissue stimulating hormone sensitive lipase, leading to hydrolysis of TGs to FFA and glycerol