Adrenoreceptor Agonists Part 2 Flashcards
alpha 1 receptor activation causes vaso____ and a ____ in blood pressure
vasoconstriction and rise in blood pressure
in general, a2 receptor activation does what do blood pressure?
when can the opposite happen?
decrease in blood pressure
when a2 agonists are given IV or very high oral doses they may cause vasoconstriction – not normally
a2 agonists can be used as ________ in the treatment of hypertension
sympatholytics
effect of BETA receptor activation on the heart
increases cardiac output, incrased contractility, increased heart rate
beta receptor activation causes vaso______
dilatio
what is isoproterenol and what is it used for
NONSELECTIVE BETA AGONIST
binds b1,b2,b3
goal is to slightly increase systolic blood pressure and to lower diastolic, so that the overall BP is decreased
beta receptor activation results in positive ____, ___, and ____ effect
chronotropic, dromotropic, and inotropic
increased heart rate, electrical conduction, and increased contractility
beta blockers are able to reduce these influences
what does inotropic mean
NOT related to ion increase
relates to contractility force
what does lusitropy mean
relaxation of the heart
what effect does dopamine have on the heart***
activates beta 1 receptors, resulting in an increased heart rate
what happens when dopamine is administered IV
vasodilation of renal/splanchic/coronary/cerebral vessels
at HIGH doses of infucion, may cause vasoconstriction and MIMICS THE ACTIONS OF EPINEPHRINE
Name 2 drugs that can be used to treat glaucoma
cholinergic agonist
beta antagonist
______ are important in the treatment of asthma
beta 2 agonists
bronchial smooth muscle dilates
effect of phenylephrine on the eye
the eye contains alpha receptors - specifically the radial pupillary dilator muscles
phenylephrine will activate these alpha receptors and cause mydriasis (dilation)
true or false
beta agonists can be used to treat glaucoma
FALSE - beta antagonists
by decreasing the production of aqueous humor in the eye
what do alpha2 agonists do to the eye
increase the outflow of aqueous humor and thus reduce intraocular pressure
what is urinary continence
ability to control bladder function without any leaks
what drug can be used to promote urinary continence**?
the bladder base/urethral sphincter/prostate contain alpha 1 receptors
therefore, an alpha 1 agonist will mediate contraction and promote urinary continence
what drug can play a role in normal ejaculation?
alpha receptor activation in the ductus deferens/seminal vesicles/prostate
name a sympathomimetic drug that produces symptoms of dry mouth
clonidine
what are apocrine sweat glands?
NONthermoregulatory sweat glands that respond to stress and adrenoceptor stimulation
under control of SYMPATHETIC nervous system
true or false
beta adrenoceptor activation in fat cells leads to INCREASED lipolysis
true
what receptors INHIBIT lipolysis and how?
alpha 2 receptors****
inhibit lipolysis by decreasing intracellular cAMP levels (works through Gi!)
when beta adrenoceptors in fat cells are activated, what happens?
increased lipolysis
release of free fatty acids and glycerol into the blood
what kind of drugs enhance GLYCOGENOLYSIS in the liver?
sympathomimetics (beta)
leads to increased glucose in circulation
true or false
beta adrenoceptor stimulation leads to both increased lipolysis AND glycogenolysis
true
enhanced activation of the beta adrenergic system will lead to…………***
metabolic acidosis
true or false
sympathomimetic drugs lead to glycogen synthesis
FALSE
glycogenolysis
effect of sympathomimetic drugs on the liver
glycogenolysis - glucose dumped into bloodstream and may cause METABOLIC ACIDOSIS**
TRUE OR FALSE
sympathomimetic drugs will lead to decreased glucose levels in the blood
FALSE - increased bc of increased glycogenolysis
INSULIN SECRETION is stimulated by _____ and inhibited by______
stimulated by beta receptors (Gs) inhibited by alpha 2 receptors (Gi)***8
where is insulin stored and what is needed to push it out?
need calcium
in vesicles in the pancreas
renin secretion is stimulated by ____ and inhibited by ______**
stimulated by B1 and inhibited by a2
effect of sympathomimetics on the CNS
catecholamines almost completely excluded from the CNS bc of the BBB
only at very high rates of infusion are CNS effects observed - like adrenaline rush and impending doom feeling
NONCATECHOLAMINES, however, that are INDIRECT adrenergic agonists like amphetamine, READILY ENTER THE CNS FROM CIRCULATION and provide mild altering effects and improved attention
true or false
epinephrine binds both alpha and beta receptors
true
since epinephrine binds both alpha and beta receptors, explain its effects
a very potent vasoconstrictor and cardiac stimulant
HOW does epinephrine cause a rise in blood pressure?
can the total diastolic pressure ever decrease?
has positive inotropic and chronotropic effects on the heart (B1) and causes vasoconstriction (alpha receptor)
HOWEVER, also activates B2 bc it’s not selective. this causes vasodilation and thus the total diastolic pressure may actually decrease
epinephrine’s activation of _____ receptors in the skeletal muscle contributes to the incresed blood flow during exercise
B2
Which receptor does norepinephrine have little effect on?
B2
true or false
norepinephrine increases peripheral resistance and increased both diastolic and systolic blood pressure
true
however, reflexes tend to overcome to positive chronotropic effects of NE (speed of heart rate) but the inotropic effects remain (increased contractility)
what leads to parkinsons disease and what is the treatment?**
deficiency of dopamine in the basal ganglia
treated with the precursor of dopamine - levodopa
what is dopamine?
a neurotransmitter in the CNS whose reward stimulus is associated with addiction
dopamine receptors are targets for what kind of drugs
antipsychotics
ENDOGENOUS dopamine has important effects in regulating what?
sodium excretion and renal function
explain the use of phenylephrine.
include its:
-selectivity
-clinical use
-duration of action compared to the catecholamines
selective alpha 1 agonist
used as a nasal decongestant - causes vasoconstriction
it has a longer duration of action than the catecholamines because it is NOT inactivated by COMT
(catechol-O-methyltrasnferase)
what is midrodrine used for and what is it’s selectivity**
prodrug - hydrolysied to desglymidodrine
selective a1 receptor agonist (like phenylephrine)
used to treat ORTHOSTATIC HYPOTENSION
What are alpha 2 selective agonists used for?
they decrease blood pressure (unless directly applied to a blood vessel)
so used for the treatment of hypertension
effect and selectivity of isoporterenol
potent beta receptor agonist (binds all) - has little effect on a receptors
positive chronotropic and inotropic actions
potent vasodilator and decreases BP, INCREASES cardiac output
what is oxymetazoline
direct acting alpha agonist
used as a decongestant bc it constricts nasal mucosa
** beta 2 selective agonist agents are important in the treatment of…..
give a specific drug
ASTHMA
terbutaline
causes bronchodilaiton and vasodilation
what is the effect of Beta1 selective agents?
incresaed cardiac output
selectivity and effects of dobutamine compared to isoproterenol
beta selective agonist
greater inotropic than chronotropic effects compared to isoprotereno
name 2 mixed acting sympathomimetics and what they are used as***
ephedrine and pseudoephedrine
decongestants
what is the duration of action of ephedrine?
what was it originally used as?
high bioavailability and long duration of action - hours
activates B receptors so used earlier in asthma treatment
ephedrine effects on CNS
mild stimulant
amphetamine is a CNS _____**
stimulant
the action of amphetamine is mainly through the release of ____ but also ____
mainly through release of norepinephrine but also dopamine
name 2 drugs that are very similar to amphetamine
which has an even higher ratio of central to peripheral actions than amphetamine
methamphetamine and methylphenidate
methamphetamine has even higher rate of central to peripheral actions
amphetamine-like indirect acting sympathomimetics can also be called……..
displacers
what is tyramine***
a byproduct of tyrosine metabolism
produced in high conc in protein rich foods
what is modafinil
a psychostimulant
what metabolizes tyramine?
MAO (monoamine oxidase)
MAO inhibitors should not be taken with ______ and why?
should not be taken with high tyramine diet
tyramine is a regulator of blood pressure.
if a MAO inhibitor is taken, there will be too much tyramine in the body bc it can’t be metabolized by MAO —– increased BP
name some drugs that are indirect acting adrenergic agonists and are catecholamine reuptake inhibitors
tricyclic antidepressants and other antidepressants, cocaine
atomexetine (used for ADHD - selective for NE)
reboxetine - same
sibutramine - serotonin and NE
duloxetine - same
tricyclic antidepressants are reuptake inhibitors.
they are selective for inhibiting the reuptake of what 2 things?
norepinephrine
serotonin
explain the MOA of cocaine
inhibits dopamine reuptake into neurons in the CNS
readily enters the CNS and produces amphetamine-like effect that is shorter but more intense than amphetamine
what type of drugs are used for asthma treatment
b2 selective drugs
what drug is used for mydriasis in ophthalmic examination
phenylephrine
what kind of drugs relax the uterus and are used to suppress premature labor>
beta 2 selective
drugs used for ADHD
low dose methylphenidate
alpha 2 agonists like clonidine and guanficine
atomexitine - norepinephrine reuptake inhibitor
