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Pharmacology > Adrenergic transmission > Flashcards

Adrenergic transmission Flashcards

1
Q

Adrenergic receptors

-classification

A

-G protein coupled receptor, catecholamines bind to it

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2
Q

Adrenergic receptors

-types

A
  1. Alpha 1
  2. Alpha 2
  3. Beta 1
  4. Beta 2
  5. Beta 3
  6. Dopamine

LOOK AT TABLE IN THE SUMMARY

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3
Q

Presynaptic regulation

  • alpha 2 receptors
  • beta 2 receptors
A
  • Alpha 2 receptors: decrease further release of adrenaline

- Beta 2 receptors: facilitate the release of adrenaline

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4
Q

Main effects of adreno-receptors

A

LOOK AT TABLE IN THE SUMMARY

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5
Q

Noradrenergic junction (9)

A
  1. Tyrosine is transported into the noradrenergic ending by sodium-dependent carrier
  2. Tyrosine is converted into Dopamine by tyrosine hydroxylase
  3. Dopamine is transported into the vesicle by VMAT (inhibited by reserpine)
  4. Dopamine is converted to norepinephrine by dopamine-b- hydroxylase
  5. Release of transmitter
  6. Voltage-sensitive Ca2+ channels open
  7. Increase intracellular calcium
  8. Vesicle fuses with the membrane (inhibited by bretylium)
  9. Norepinephrine diffuses out or it is transported into the cytoplasma of the terminal by NET or uptake 2
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6
Q

Which adrenoreceptors does norepinephrine and epinephrine activate?

A

Norepinephrine –> alpha 1, alpha 2 and beta 1

Epinephrine –> ALL

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7
Q

Noradrenaline transport system (3)

A
  1. Vesicular monoamine transporter (VMAT) –> synaptic vesicle membrane, NA=A=ISO
  2. Uptake 1 (NET) –> neuronal membrane, NA>A>ISO
  3. Uptake 2 –> non-neuronal cell membrane, A>NA>ISO
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8
Q

Adrenergic drugs - agonists

-classification

A

Direct acting

  1. Alpha: nonselective (norepinephrine), alpha 1 selective (pheylephrine), alpha 2 selective (clonidine)
  2. Beta: nonselective (isoproterenol), beta 1 selective (dobutamine), beta 2 selective (albuterol)

Indirect acting

  1. Releasers (amphetamine)
  2. Reuptake inhibitors (cocaine)
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9
Q

Effects of adrenaline (6)

A
  • it is not selective, it has a balanced effect to all adreno receptors
  • increases heart rate
  • slightly decrease peripheral resistance
  • Beta 1 –> causes tachycardia
  • Beta 2 –> causes vasodilation
  • Systolic pressure would be elevated due to alpha 1 and alpha 2 (leads to vasoconstriction)
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10
Q

Effects of noradrenaline (6)

A
  • high potency to alpha receptors
  • increase blood pressure
  • increase peripheral resistance
  • decreases permeability of blood vessels
  • Decreased heart rate –> baroreceptors are activated
  • Increases systolic and diastolic blood pressure
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11
Q

Effects of isoproterenol (5)

A
  • tends equally on beta 1 and beta 2
  • By action on Beta 2 –> causes vasodilation on muscles
  • By action on Beta 1 –> tachycardia
  • No effect on systolic
  • Slight decrease in diastolic –> because main effect of this drug on blood vessels is on muscle via beta 2
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12
Q

Dopamine (5)

A
  • used in acute heart failure, hypotensive shock
  • activates alpha, beta and dopamine receptors in an independent manner
  • low doses –> dopamine receptors
  • higher doses –> b1 receptors
  • even higher doses –> alpha 1 receptors
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13
Q
  • Clinical uses of adrenaline (5)
  • Unwanted effects
  • Contraindications
A
  • cardiac arrest
  • anaphylatic shock
  • to reduce local bleeding
  • to prolong local anaesthetics action
  • angina pectoris, cerebral hemorrhages, arrhythmia
  • non selective b-adrenoreceptors antagonist users
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14
Q

Alpha 1 adrenoreceptors agonists

  1. Names
  2. Clinical use
  3. Unwanted effects
  4. Contraindications
A
  1. Pseudoephedrine, xylometazoline
  2. hypotension, nasal decongestion, to cause mydriasis, shock
  3. hypertension, arrhythmia, headache
  4. close-angle glaucome, severe hypertension
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15
Q

Alpha 2 adrenoreceptors agonists

  1. Names
  2. Clinical use
  3. Unwanted effects
  4. Contraindications
A
  1. Clonidine, Methyldopa
  2. in the CNS it inhibit sympathetic nervous system output and lower BP (clonidine), glaucoma, withdrawl in addicts, hypertension (in pregnancy methyldopa)
  3. sedation, bradycardia, sexual dysfunction
  4. depression, bradycardia, ischemic heart disease
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16
Q

Beta 1 adrenoreceptors agonists

  1. Names
  2. Clinical use
  3. Unwanted effects
  4. Contraindications
A
  1. Dobutamine
  2. cardiogenic shock, acute heart failure, after heart surgery
  3. tachycardia, arrhythmia, increase of myocardial damage
  4. hypertension, narrowing of aortic heart valve, atrial fibrillation
17
Q

Beta 2 adrenoreceptors agonists

  1. Names
  2. Clinical use
  3. Unwanted effects
  4. Contraindications
A
  1. Salbutamol
  2. asthma, chronic obstructive pulmonary disease, premature labor
  3. tachycardia, arrhythmia, tremor, hypotension
  4. recent myocardial infarction, coronary heart disease, hypertension
18
Q

Ephedrine and Pseudoephedrine (4)

A
  • mixed action agonists
  • cause activation of adrenergic receptors by direct binding and release of stored NE from pre synaptic terminals
  • Ephedrine: vasoconstriction, bronchodilation
  • Pseudoephedrine: vasoconstriction, bronchodilation, decrease mucus production
19
Q

Amphetamine (4)

A
  • treatment of attention-deficit/hyperactivity disorders (ADHD)
  • stimulate CNS
  • it binds to transporter proteins for amines, enters the neurons and disrupts the storage of monoamines in synaptic vesicles.
  • it is able to cause the monoamine transporter proteins to run in reverse, increases the release of monoamines (dopamine and NE) in the synaptic cleft
20
Q

Adrenoreceptors antagonists t

-classification

A
  • alpha and beta blockers
  • can be either selective or non-selective

Alpha
Alpha 1 selective - prazosin
Alpha 2 selective - yohimbine
nonselective - irreversible (phenoxybenzamine) or reversible (phentolamine)

Beta 
Nonselective (propanolol)
Beta 1 selective (atenolol)
Beta 2 selective (butoxamine)
21
Q

Alpha adrenoreceptors antagonists: non selective, a1, a2

  1. Names
  2. Clinical use
  3. Unwanted effects
  4. Contraindications
A
  1. Prazosin (a1 selective), Doxazosin (a1 selective), Tamsulosin (a1 selective), Yohimbine (a2 selective)
  2. severe hypertension, benign prostatic hypertrophy
  3. hypotension, tachycardia, nasal congestion, impotence, failure to ejaculate
  4. intra-operative floppy iris syndrome, painful erection
22
Q

B- adrenoreceptors antagonists

  1. Names
  2. Clinical use
  3. Unwanted effects
A
  1. Timolol, propranolol, metoprolol, labetalol, nebivolol
  2. glaucoma, anxiety, migrane, angina, heart failure, hypertension
  3. bronchoconstriction, bradycardia, fatigue, hypoglycemia, cardiac depression
23
Q

Drugs used in open angle glaucoma (2)

A

Pilocarpine –> ciliary muscle contraction, opening of trabecular meshwork, increased outflow

Beta blockers - timolol –> decreased aqueous secretion from the ciliary epithelium

24
Q

Beta blockers (4)

A
  1. Propranolol: non selective –> beta 1 and beta 2 antagonism
  2. Metoprolol: beta 1 selective blockers
  3. Labetolol: mixed antagonist for beta and alpha 1, non selective for beta 1 and beta 2 antagonism, ISA
  4. Nebivolol: beta 1 selective blocker
25
Q

Intrinsic sympathomimetic activity (ISA) (5)

A
  • Both agonism and antagonism at a given b receptor
  • Labetalol –> exhibit ISA
  • not used after myocardial infarction, may also be less effective in the management of angina and tacharrhythmia
  • it depends on the concentration of beta blocker and concentration of the antagonized agent
  • Very low amount of noradrenaline –> when the drug binds –> it has agonist activity
  • If the amount of norepinephrine increases –> the drug function will change –> it will have antagonist activity
26
Q

How does the sympathetic system affects…?

  1. Brain
  2. Eyes
  3. Respiratory system
  4. Heart
  5. GI
  6. Bladder
  7. Immune system
A
  1. do not remember anything –> degeneration of cholinergic centers
  2. pupils dilate in order to see things better
  3. bronchodilation, stop secretion of respiratory system –> we need more O2
  4. BP increases
  5. shut down, sphincter is constricted but the rest is relaxed
  6. relaxed but sphincters are constricted
  7. shut down, because it is an energy demanding system
27
Q

Clonidine

-what is it used for? (6)

A
  1. treat high blood pressure
  2. attention deficit
  3. hyperactivity disorder,
  4. drug withdrawal,
  5. menopausal flushing,
  6. diarrhea
28
Q

Adrenergic vs. cholinergic neurons

A

Cholinergic –> acetlycholine is metabolized by acetylcholinesterase

Adrenergic –> noradrenaline is uptaken, there are NO enzymes to degrade it

29
Q

What happens in the eye by action of ….?

  1. alpha 1
  2. alpha 2
  3. beta 2
A
  1. stimulatory effect –> contraction of iris radial muscle –> dilation of pupils
  2. decrease aqueous humor formation and increase uveoscleral outflow
  3. increase aqueous humor formation and decrease uveoscleral outflow

Pharmacology (29 decks)

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