Week 6: Adrenergic Agonists Flashcards Preview

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Flashcards in Week 6: Adrenergic Agonists Deck (74):
1

Where are alpha 1 receptors found?

vascular smooth muscle of skin and splanchnic regions, GI and bladder sphincters

2

What is the effect of alpha 1 receptor stimulation?

Contraction/constriction

3

Which G protein is associated with alpha 1 receptors?

Gq

4

How do alpha 1s exert their effects?

Gq protein -> stim of phospholipase C -> increased IP3 -> inc intracellular [Ca]

5

Where are alpha 2 receptors found?

sympathetic post-gang nerve terminals (autoreceptors), platelets, fat cells, walls of GI tract

6

What is the effect of alpha 2 receptor stimulation?

Relaxation or dilation. Inhibition of neural NE release.

7

Which G protein is associated with alpha 2 receptors?

Gi

8

How do alpha 2s exert their effects

Gi protein -> activates Na/H antiporter OR inhibits adenylate cyclase -> dec cAMP

9

Where are beta 1 receptors found?

Heart: SA node, AV node, ventricular muscle, JG apparatus, adipose tissue

10

What is the effect of beta 1 stimulation

Increased HR (chronotropic), inc conduction velocity (dromotropic), inc contractility (inotropic)

11

Which G protein is associated with beta 1 and 2 receptors?

Gαs

12

How do beta 1 and 2s exert their effects?

Gαs -> stimulation of adenylate cyclase -> inc cAMP

13

Where are beta 2 receptors found?

vascular smooth muscle of skeletal muscle, bronchial smooth muscle, walls of the GI tract and bladder

14

What is the effect of beta 2 stimulation?

Relaxation e.g. dilation of vascular smooth muscle and bronchioles, relaxation of bladder wall.

15

Compare isoproterenol, epi, and NE sensitivity of beta 1 receptors

isoproterenol > epi = NE

16

Compare isoproterenol, epi, and NE sensitivity of beta 2 receptors

isoproterenol > epi >> NE

17

Compare isoproterenol, epi, and NE sensitivity of alpha 1 receptors

epi >/= NE >> isoproterenol

18

Compare isoproterenol, epi, and NE sensitivity of alpha 2 receptors

epi >/= NE >> isoproterenol

19

alpha 1 agonists

NE, phenylephrine

20

Alpha 1 antagonists

-zosin e.g. Prazosin

21

Alpha 2 agonist

Clonidine

22

Beta 1 agonists

NE, isoproterenol, dobutamine

23

Beta 1 antagonists

Propranolol (non-selective), Metoprolol

24

Beta 2 agonists

Isoproterenol, albuterol

25

Beta 2 antagonists

Propranolol, butoxamine

26

-terol suffix

B2 agonist

27

What components of the CV system are innervated by sympathetics?

Atria, ventricles, arterioles, and veins

28

How are NE and Epi synthesized?

Tyrosine -> DOPA -> Dopamine -> NE -> Epi (in adrenal medulla)

29

What enzyme is rate limiting in sympathetic neurotransmitter synthesis?

Tyrosine hydroxylase

30

What does Reserpine do?

Irreversibly blocks vesicular monoamine transporter -> no sequestration of free NE -> NE degraded by MAO and COMT

31

Where does the cholera toxin act?

Irreversibly activates Gsalpha -> secretion from colon -> death by dehydration

32

What does Dobutamine do?

Selective B1 agonist. Increases HR and contractility.

33

Albuterol MOA

B2 agonist -> relaxation of smooth muscle of bronchioles and uterine lining. Decreases BP via dec TPR.

34

Phenylephrine MOA

Alpha 1 agonist -> inc BP.

35

Isoproterenol MOA

Nonselective Beta agonist

36

How does epinephrine reversal work?

Give epi -> rise in BP. Then give α-antagonist -> no α actions from epi. E.g. vasoconstriction is interrupted, but vasodilation of other vascular beds caused by stimulation of β receptors is not blocked. Therefore alpha antagonist -> dec BP in response to epi

37

Where are muscarinic receptors?

Postganglionic parasympathetic targets (heart and vessels) + sweat glands and vessels (postganglionic sympathetic cholinergic)

38

How are adrenergic amines released?

Stim of nicotinic receptors on postganglionic nerve

39

How does NE inhibit own release?

Via alpha 2 autoreceptor

40

Action of cocaine

Inhibits axoplasmic pump -> potentiates sympathetic response

41

What does Guanethidine do?

Induces release of NE from vesicle leading to degradation by MAO -> reduced sympathetic response

42

What does pargyline do? (IMPORTANT!)

MAO inhibitor (potentiates sympathetic responses), blocks Guanethidine effects

43

What 2 enzymes degrade adrenergic amines, and where are they located?

COMT (catechole-O-methyl transferase) in cytoplasm, MAO in mitochondria

44

Effect of dopamine?

Dilation of renal and mesenteric vasculature (dopaminergic) vasoconstrictor (alpha 1) at higher doses. Positive inotrope (B1), release NE from nerves

45

Dobutamine therapeutic use

CHF, AMI with HF

46

What adrenergic agonist can raise HR, SV, and TPR respectively?

HR and SV: B1, TPR: alpha 1

47

What autonomic activity can result in decreased HR, SV, and TPR respectively?

HR: muscarinic, SV: none, TPR: beta 2 and muscarinic

48

Therapeutic use of dopamine

shock (maintains renal perfusion at low dose via dopaminergic receptor), hypotension (inc BP and CO), chronic refractory HF

49

What is midodrine? What is it used for?

Alpha 1 agonist for orthostatic hypotension

50

What is phenylephrine? What is it used for?

Alpha 1 agonist. Treats hypotension, paroxysmal atrial tachycardia, decongestant, topical vasoconstrictor and mydriatic

51

B2 selective agonists

Metaproterenol, Terbutaline, Albuterol, Ritodrine, Salmeterol

52

Uses for B2 selective agonists

asthma (except Ritodrine which does not result in bronchodilation

53

B2 agonists for delaying labor

Ritodrine, terbutaline

54

Major side effects of B2 agonists

Tremor (skel muscle B2 stim), HA (B2 vasodilation), tachycardia, palpitations (b1)

55

What is isoproterenol?

Synthetic catecholamine that stimulates beta receptors -> vasodilation (b2) and tachy (b1)

56

NE effects

Vasoconstriction (alpha 1), Inc HR and force (B1)

57

NE therapeutic use

hypotension

58

Epi effects

vasoconstricts (a1) vasodilates (b2) - vasoconstriction generally wins therapeutically, inc HR, force (can have reflex vagal stim -> dec HR)

59

Epi uses

Hypersensitivity reaction, low BP, bronchospasm (a1 and B2). With anesthetic -> vasoconstrict, prevent diffusion away

60

How do indirectly acting sympathomimetics work? What is an example?

Release NE from nerves by reversing catecholamine axoplasmic uptake pump. Phenylethylamines e.g. amphetamine.

61

Amphetamine therapeutic uses

Narcolepsy, obesity, hyperkinetic syndrome

62

How does Ephedrine work?

releases NE -> inc BP via a1 and b1, vasodilates via B2

63

Therapeutic uses of ephedrine

Bronchospasm. For colds: NE -> vasoconstriction -> dec mucosal congestion (a1), bronchodilates (b2)

64

How does pseudoephedrine work?

Same as ephedrine, just a stereoisomer.

65

Which drugs block accumulation of NE in nerves, potentiating sympathetic action? (2)

Cocaine, Imipramine

66

Which drugs reverse the axoplasmic transporter, mimicking symp stim (3)?

Tyramine, amphetamine, ephedrine

67

Which drug blocks vesicular accumulation of NE leading to its degradation?

Reserpine

68

Which drugs release NE from vesicles -> depletion? (2)

Guanethidine, guanadrel

69

Epi acts on what adrenergic receptor(s)?

a1, a2, b1, b2

70

NE acts on what adrenergic receptor(s)?

a1, a2, b1

71

Phenylephrine acts on what adrenergic receptor(s)?

alpha 1

72

Dobutamine acts on what adrenergic receptor(s)?

B1

73

Ritodrine and Terbutaline act on what adrenergic receptor(s)?

B2

74

Albuterol and other -terols work on what adrenergic receptor(s)?

B2