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Pharmacology II > Lect 5: adrenergic stimulants > Flashcards

Lect 5: adrenergic stimulants Flashcards

1
Q

What is the rate limiting step in the conversion from tyrosine to NE

A

conversion of tyrosine to l-dopa

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2
Q

Where is NE converted to epinephrine

A

adrenal medulla

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3
Q

effect of tyramine and amphetamine on NE release

A

increase or cause the release of NE from the presynaptic terminal. Therefore these drugs have an effect only if noradrenergic innervation is intact.

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4
Q

antidepressants and cocaine effect on NE

A

block the reuptake of NE into the presynaptic terminal

  • This is the main mechanism for termination of the action of NE in the synaptic cleft.
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5
Q

NE is metabolized by what two enzymes

A

monoamine oxidase (MAO) and catechol-O-methyl transferase (COMT).

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6
Q

List the steps from tyrosine to NE

A

Tyrosine -> L-DOPA-> dopamine -> NE

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7
Q

What are adrenergic receptors

A

alpha and beta receptors

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8
Q

differentiate between direct and indirect drugs

A
  • direct: act on receptors to mimic sympathetic stimulation
  • indirect: increase synthesis, cause release, or inhibit re-uptake/breakdown
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9
Q

what happens to effect of direct and indirect drugs with denervation

A
  • abolish effect of indirect drugs
  • may enhance effect of direct drugs
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10
Q

NE, epinephrine, and isoproterenol: list order of effect on alpha receptors

A
  • epi > NE > > isoproterenol
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11
Q

what is phenylephrine

A

an alpha 1 agonist

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12
Q

alpha 1 acts via what G protein

A
  • Gq
  • excitatory
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13
Q

alpha 2 acts via what G protein

A
  • Gi
  • inhibitory
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14
Q

what is clonidine

A

alpha 2 agonist

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15
Q

which adrenergic receptor is responsible for constriction of blood vessels to skin, kidneym mucous membranes

A

alpha 1

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16
Q

which adrenergic receptor is responsible for the relaxation of BV to skeletal muscle

A

beta 2

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17
Q

which adrenergic receptor is responsible for relaxation of gut wall and bronchioles

A

beta 2

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18
Q

which adrenergic receptor is responsible for cardiac excitatory

A

beta 1

19
Q

which adrenergic receptor is responsible for lipolysis in fat cells

A

beta 3

20
Q

which adrenergic receptor is responsible for modulation of insulin and renin

A

beta 1

21
Q

Which drug has a high affinity for all beta receptors

A

Isoproterenol

22
Q

NE does not have much of an effect on which beta receptor

A

Beta 2

23
Q

Epi and NE affinity for B1 receptors

A

same effect; but less than isoproterenol

24
Q

what is dobutamine

A

beta 1 agonist

25
Q

function of dobutamin on heart and renin secretion

A
  • increase HR and contractility
  • increase renin secretion
26
Q

what is albuterol

A

a beta 2 agonist

27
Q

function of albuterol on bronchiol smooth muscle, skeletal muscle BV, uterus, bladder, and GI muscle?

A

Relax

28
Q

which adrenergic receptor is responsible for glycogenolysis/gluconeogenesis

A

beta 2

29
Q

function of dopamine 1 receptors

A
  • Dilate renal BV, increase renal blood flow
30
Q

alpha receptor stimulation by NE effect on cardiovascular function

A
  1. Skin and splanchnic blood vessels have mainly α receptors
    • Smaller blood vessels are more densely innervated than larger ones, therefore the largest effect is on small blood vessels.
  2. Net effect is to increase blood pressure.
    • Peripheral artery resistance is increased and venous capacity is decreased
    • Increased blood pressure will stimulate baroreceptors, which then increase vagal input to slow the heart
31
Q

what happens to cardiovascular response if atropine is given prior to norepinephrine

A

the vagal reflex is inhibited, the baroreceptor effect will not occur, and heart rate will increase

32
Q

NE must be injected; why is it used only rarely, for severe hypotensive crisis

A

NE can cause severe vasoconstriction at the infusion site and can cause necrosis

33
Q

NE has what strength of effect on alpha, beta 1 and beta 2 receptors?

A

stimulates α and β1 receptors, with little effect on β2 receptors

(α = β1>> β2)

34
Q

epinephrine has what strength of effect on alpha, beta 1 and beta 2 receptors?

A

Epinephrine stimulates α, β1 and β2 receptors, which makes the effect complex

***the effect depends upon the dose administered

35
Q

which receptors are most sensitive to epinephrine

A
  • B2 receptors in blood vessels supplying skeletal muscle are more sensitive to epinephrine than alpha receptors
36
Q

what effect does low dose epinephrine stimulation have on alpha, beta 1 and beta 2 receptors

A
  • beta1 receptors increase heart rate, conduction, contractility
    • (inc systolic pressure)
  • alpha receptors constrict blood vessels in the skin, mucosa and kidney
    • increased systolic
  • beta2 receptors relax blood vessels supplying skeletal muscle
    • decrease in diastolic pressure
    • pulse pressure increases
    • since mean blood pressure is unchanged, there is little reflex slowing of the heart rate -> heart rate is increased
37
Q

what effect does high dose of epinephrine have on systolic, diastolic, and mean arterial pressure

A
  • alpha receptors in blood vessels supplying skeletal muscle are stimulated
    • diastolic pressure increases
  • increases blood pressure substantially
    • both systolic and diastolic pressure will increase
    • mean pressure increases
      • ​there is less increase in heart rate
38
Q

epinephrine has a short duration of action and must be administered via

A

injection

39
Q

Explain how an alpha block can be used to reverse the effect on high dose epinephrine and not norepinephrin

A
  • taking out alpha receptors from high dose epinephrine leaves beta 2 receptor activation which causes vasodilation of BV to skeletal muscle and BP drops
  • NE has no effect on B2 receptors
40
Q

what are the primary uses of epinephrine

A
  • bronchodilation in severe asthma attack via B2
  • vasoconstrictor: decrease diffusion of injected drugs such as local anesthetics
  • anaphylactic shock to restore blood pressure, decrease bronchospasm, decrease congestion and angioedema, and reverse cardiovascular collapse
41
Q

what are some side effects of epinephrine

A

tremor, throbbing headache, increased blood pressure, tachycardia, angina

42
Q

why is epinephrine contraindicated in people taking beta-blocker

A

unopposed effects on α receptors may lead to severe hypertension!

43
Q

what is Ephedrine

A
  • a drug that : stimulates α and β receptors similar to low-dose epinephrine, and also increases NE release
  • long duration of action
    • CNS stimulant
    • bronchodilator
  • taken off market due to deaths from high BP and stroke

Pharmacology II (9 decks)

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