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CPR Exam 1 > adrenergic receptors > Flashcards

adrenergic receptors Flashcards

1
Q

Alpha receptors generally mediate

A

Excitation

except in GI

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2
Q

Beta receptors generally mediate

A

Inhibition

except in heart

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3
Q

Alpha 1

A

Radial muscle - contracts
vascular smooth muscle, skin, splanchnic vessels - contracts
skeletal muscle vessels - contracts
GI - contracts sphincters

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4
Q

Alpha 2

A

GI - walls relax

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5
Q

Beta 1

A

SA node - accelerates
Ectopic pacemakers - accelerates
contractility - increases
renin release

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6
Q

Beta 2

A 
ciliary muscle - relaxes (lens thins) 
skeletal muscle - relaxes 
bronchiolar smooth muscle - relaxes 
GI smooth muscle - relaxes walls 
GU smooth muscle - bladder wall relaxes 
uterus - relaxes
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7
Q

What tissues have alpha receptors?

A 
vascular smooth muscle, skin, splanchnic vessels - contracts 
skeletal muscle vessels - contracts 
enteric NS - inhibits 
uterus - contracts 
Ejaculation 
pilomotor smooth muscle - contracts 
apocrine (stress) - increases 
liver gluconeogenesis and glycogenolysis
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8
Q

In general, Alpha 1 receptors are found on

A

postsynaptic sympathetic effector sites

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9
Q

In general, Alpha 2 receptors are found on

A

presynaptic neurons (some postjunctional sites)

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10
Q

In general, Beta 1 receptors are found on

A

adipocytes and the heart

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11
Q

In general, Beta 2 receptors are found on

A

smooth muscle (some presynaptic neurons)

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12
Q

In general, Beta 3 receptors are found on

A

adipocytes but has a low affinity for endogenous catecholamines

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13
Q

what type of receptors are alpha and beta adrenergic receptors?

A

G protein coupled

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14
Q

What effector systems does alpha 1 activate?

A

stimulates PLC-IP3-DAG-PKC pathway via the Gq protein
=similar to M1, M3,M5
pathway stimulates intracellular calcium signaling mechanisms (contraction of smooth muscle)

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15
Q

What effector systems does alpha 2 activate?

A

inhibit adenylylcyclase activity via Gi protein

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16
Q

what effector systems do Beta receptors activate?

A

all subtypes stimulate activity of adenylyl cyclase via Gs protein
though B1 also does increase L type Ca+2 channel activation

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17
Q

Alpha 1 agonists

A

phenylephrine

methoxamine

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18
Q

phenylephrine

A

potent vasoconstrictor
increases both systolic and diastolic pressure with little cardiac effect
induce reflex bradycardia
nasal decongestant (long term can damage mucosa)
mydriatic agent
not a substrate for COMT

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19
Q

Methoxamine

A

potent vasoconstrictor
used to treat hypotensive states (shock, spinal anesthesia)
induces reflex bradycardia

longer duration of action then Phenylephrine
not substrate for COMT or MAO

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20
Q

Alpha 2 agonists

A

clonidine

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21
Q

Clonidine

A

IV infusion causes acute increase in BP due to a2 stimulation in vascular beds. Hypertensive response is transient

followed by prolonged hypotension - due to stimulation of a2 in the CNS which depresses sympathetic outflow to periphery

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22
Q

Beta 1 agonists

A

dobutamine

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23
Q

Dobutamine

A

similar to dopamine in structure but has higher affinity for beta 1 receptors
Inotropic agent to tx CHF
greater affect on contractility than HR
dilates renal vasculature to preserve kidney function

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24
Q

beta 2 agonists

A

terbutaline

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25
Q

Terbutaline

A

bronchodilator with minimal cardiac effects at normal doses
inhaled to relieve bronchospasm
given orally, delay of 1 to 2 hours in effect, can be long term for Asthma, emphysema, bronchitis
inhibit premature labor
not metabolized by COMT or MAO and not taken up into adrenergic terminals

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26
Q

What drug is Albuterol similar to?

A

Terbutaline

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27
Q

Indirect adrenergic agonists

A

Amphetamine
Dextroamphetamine
methamphetamine

promote the release of NE from adrenergic nerve terminals

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28
Q
  • Heart failure (inotropic > chronotropic), cardiac stress testing
A

Dobutamine

b1>b2,a

29
Q
  • hypotension (vasoconstrictor), ocular procedures (mydriatic), rhinitis (decongestant)
A

phenylephrine

a1>a2

30
Q

Acute asthma*

A

Albuterol

b2>b1

31
Q

salmeterol*

A

long term asthma or COPD control

b2>b1

32
Q

*Reduce premature uterine contractions

A

Terbutaline

b2>b1

33
Q

*indirect general agonist, releases stored catecholamines

nasal decongestant, urinary incontinence, hypotension

A

Ephedrine

34
Q

Ephedrine

A

releases NE from nerve terminals
effects resemble NE - both alpha and beta
also has some direct agonistic effects on alpha and beta
Alpha - tx urinary incontinence
Beta - bronchodilation
CROSSES BBB - potent CNS stimulant = high dose Insomnia and hypertension

35
Q

Primary use of Ephedrine

A

beta - relieve bronchoconstriction and mucosal congestion associate with asthma, bronchitis and bronchial spasms. Effective oral and long lasting. not metabolized by MAO or COMT

Alpha - pressor agent and nasal decongestant and tx stress incontinence in women

36
Q

What is gradually replacing Ephedrine as a bronchodilator?

A

Terbutaline and Albuterol

they are more selective for bronchiolar receptors

37
Q

Amphetamine

A

induces NE release, indirectly stim a and b receptors
systolic and diastolic pressure are increased
powerful CNS stimulants
highly potent sympathomimetic - increases alertness and decreases fatigue, relieves narcolepsy, elevates mood, and improve concentration
suppresses appetite, tolerance rapidly develops

38
Q
  • Narcolepsy, obesity, ADD

indirect general agonist, reuptake inhibitor, release stored catecholamines

A

Amphetamines

39
Q

mixed acting adrenergic agonists

A

Ephedrine

metaraminol

40
Q

Metaraminol

A

similar to phenylephrine
a1 agonist, weak b effects
false neurotransmitter (may be uptaken into vesicles with NE)
Pressor agent - both direct and indirect a1 in VSM
Tx hypotensive states (shock)

41
Q

Tx bouts of paroxysmal atrial tachycardia

A

Metaraminol (a1 agonist)
txs hypotensive states
get reflex suppression of cardiac activity in response to increased pressure

42
Q

Alpha adrenoreceptor antagonists

A

Phenoxybenzamine
phentolamine
prazosin

43
Q

Phenoxybenzamine

A

alpha1 and 2, irreversible block
mostly a1
Prevent hypertensive crisis associated with pheochromocytoma
pre-op for to prevent dangerous elevation in BP
BPH - blocks alpha in the SM of the prostate and bladder to alleviate obstructive symptoms
control autonomic hyperreflexia with spinal cord injuries

44
Q

Adverse effects of phenoxybenzamine

A

orthostatic hypotension and reflex tachycardia

Ejaculatory dysfunction - impaired smooth muscle contraction

45
Q
  • Pre-op for Pheochromocytoma removal to prevent catecholamine crisis
    Tox - orthostatic hypotension, reflex tachycardia
A

Phenoxybenzamine

46
Q

Phentolamine

A

reversible blockade of a1 and a2
a1 = a2
blocks hypertensive response to alpha agonists
tx hypertension associated with pheochromocytoma
tx erectile dysfunction

47
Q

Side effects of Phentolamine

A

orthostatic hypotension
reflex cardiac stimulation
may augment NE release
“dirty” drug does more than just block alpha receptors, also hits serotonin, K+ channels, causes histamine release

48
Q

*give to pts on MAO inhibitors who eat tyramine-containing foods

A

Phentolamine

49
Q

Prazosin

A

1000x affinity for a1 over a2
effective inhibitor of cyclic nucleotide phosphodiesterase - block contributes to direct vasodilatory effect
can act in CNS to depress sympathetic outflow
tx - hypertension, lowers BP by promoting dilation of arterial and venous smooth muscle
Both peripheral resistance and venous return are diminished

50
Q

Side effects of Prazosin

A

tends less to produce orthostatic hypotension

dizziness

51
Q

Terazosin

A

analogue to Prazosin

tx hypertension but can also tx of BPH b/c reduces obstructive symptoms and urinary urgency

52
Q

Major potential adverse effect of prazosin and terazosin

A

first dose phenomenon or marked postural hypotension and syncope. Tell pts to take first does at bedtime

53
Q

*For BPH, PTSD, HTN

has first dose effect (hypotension, dizzy,HA)

A

alpha 1 selective blockers

Prazosin - PTSD
Terazosin
Doxazosin
Tamsulosin

54
Q

Beta blockers

A

end with olol
may cause slight, transient increase in BP acutely, but long term effect will be lowering of blood pressure
decrease HR, contractility, CO and conduction velocity (increased PR interval) with high sympathetic activity
decreased renin release, effective hypotensive agents when renin is low
CNS effects

55
Q

Propranolol

A

blocks b1 and b2 competitively, b1 = b2
tx - HTN, angina, MI, glaucoma (due to depression of aq. humor secretion), reduce peripheral manifestations of hyperthyroidism (cardiac stimulation, tremor), anxiety, migraine,

56
Q

Propranolol contraindications

A

can produce life threatening bronchoonstriction in pts with asthma or COPD
potentiate hypoglycemia by antagonizing catecholamine induced mobilization of glycogen - used with great caution in diabetics
CNS - fatigue, sleep disturbances, nightmares, and depression
membrane stabilizing effect - leads to depression of membrane excitability
undergoes extensive first pass metabolism

57
Q

Metoprolol

A

cardioselective beta blocker, high affinity for b1

used to induce beta blockade in patients prone to bronchoconstriction

58
Q

Agents that inhibit NE release/storage

A

Gaunethidine

Reserpine

59
Q

Guanethidine

A

produce sympathoplegia by depleting neuronal storage of NE

transported into adrenergic neurons by uptake 1 and enters storage vesicles, release of NE causes NE to be depleted

60
Q

Primary use of Guanethidine

A

powerful hypertensive agent, to tx severe hypertension that is resistant to other agents
lowers both arterial and venous tone
among most potent orally effective hypotensive agents

61
Q

Side effects of Guanethidine

A

imbalance btw sympathetic and parasympathetic tone (orthostatic hypotension, diarrhea)
sexual dysfunction - delayed or retrograde ejaculation into the bladder
no direct effect on catecholamines in adrenal medulla
does NOT cross BBB

62
Q

Reserpine

A

inhibits uptake of catecholamines (both dopamine and NE) into neuronal storage vesicles
depletes NE
reduces catecholamine concentration in adrenal medulla

63
Q

Reserpine treats

A

mild to moderate HTN

64
Q

Side effects of Reserpine

A

orthostatic hypotension is less than guanethidine
can have more prominent CNS effects
sedation, nightmares, severe mental depression and thoughts of suicide

65
Q

Methyl Tyrosine

A

inhibits tyrosine hydroxylase, rate limiting enzyme

for management of Pheochromocytoma

66
Q

Methyldopa

A

false transmitter
analog of L-DOPA
stored in granules of adrenergic nerve terminals
used as antihypertensive agent, probably due to its action on the CNS
valueable in tx HTN complicated by renal disease

67
Q

side effects of methyldopa

A

CNS - sedation, drowsiness

sympathetic depression - orthostatic hypotensin, nasal congestion

68
Q

Cocaine

A

local anesthetic
inhibitor of uptake 1, which is primary mens of removing NE from synaptic cleft after release = leads to local accumulation of NE t receptors and overstimulation of postsynaptic effector site.

CPR Exam 1 (2 decks)

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