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FoM > Biochemical basis of drug action > Flashcards

Biochemical basis of drug action Flashcards

1
Q

What are the 4 types of receptor classes

A

ligand-gated ion channels
G protein-coupled receptors
kinase-linked receptors
nuclear receptors

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2
Q

What is an example of a ligand-gated ion channel

A

nicotinic ACh receptor (nAChr)

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3
Q

what is an example of a G protein-coupled receptor

A

Muscarinic ACh receptor (mAChr)

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4
Q

what is an example of a kinase-linked receptor

A

cytokine receptor

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5
Q

what is an example of nuclear receptors

A

steroid hormone receptors

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6
Q

What is the relative timescale for ligand gated ion channels mechanism

A

milliseconds

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7
Q

What is the relative timescale for G protein-coupled receptor mechanisms

A

seconds

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8
Q

What is the mechanism for ligand-gated ion channels

A

ligand binds to receptor
ion channel opens
influx on ions

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9
Q

How do agonists stimulate a response

A

work by binding to specific receptors to elicit a response.
signal molecule
exogenous drug

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10
Q

how do antagonists stimulate a response

A

bind to receptor
block action of biological molecule

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11
Q

What are nicotinic acetylcholine receptors permeable to

A

Na+
K+
Ca2+

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12
Q

What are the functions of ligand-gated ion channels

A

modulate fast synaptic excitation

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13
Q

How are Ca2+ channels activated in neurotransmission

A

by excitation

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14
Q

What causes vesicles to move down the pre-synaptic neuron

A

Ca+ ions flow down electrochemical gradient
move down to synaptic cleft

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15
Q

What happens after Acetylcholine diffuses across the cleft and binds to receptors on the post-synaptic membrane

A

Na+ ions move into cell via receptor conformational change
causes depolarisation

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16
Q

What drug acts as a full agonist at nicotinic acetylcholine receptors

A

nicotine

17
Q

what drug acts as a partial agonist at nicotinic acetylcholine receptors

A

varenicline

18
Q

How do partial agonists work

A

inhibits binding of biological molecule
binds to some receptors instead

19
Q

How can partial agonists be used to reduce drug craving

A

increases the amount of drug (eg nicotine) required for a maximum response

20
Q

What is the mechanism of G protein-coupled receptors

A

single peptide binds
initiates messenger system/cascade
causes cellular response

21
Q

What are the processes involved in the binding of adrenaline to B2-adrenoreceptors

A

adrenaline binds
receptor changes conformation
G protein binds
interacts with enzyme adenylyl cyclase

22
Q

When is the enzyme adenylyl cyclase inactivated

A

GTP hydrolysed

23
Q

What is the result of adrenaline binding to B2-adrenoreceptors

A

bronchodilation

24
Q

How are signals amplified by G proteins

A

ATP converted to cAMP
Activates kinase (via phosphorylation?)
sets of signalling pathway
amplification

25
Q

What part of the autonomous nervous system is adrenaline part of

A

sympathetic

26
Q

What response does adrenoreceptor a1 cause

A

vasoconstriction of blood vessels

27
Q

what response does adrenoreceptor a2 cause

A

relaxation of the GI tract

28
Q

what response does adrenoreceptor B1 cause

A

increase heart rate
increased cardiac muscle contraction

29
Q

what response does adrenoreceptor B2 cause

A

dilation of bronchi

30
Q

what response does adrenoreceptor B3 cause

A

thermogenesis in skeletal muscle

31
Q

Why do specific drugs need to be used instead or adrenaline which activates all adrenoreceptors?

A

want to activate specific receptors to get desired therapeutic effect

32
Q

which drug should be given for asthma

A

salbutamol
only activates B2
only causes bronchodilation

33
Q

what happens a receptor is continuously activated by drugs

A

receptors break down
less receptors on cell surface
desensitisation

34
Q

How can drugs that stimulate receptors be given chronically

A

via enzymes that stop the amplification of G proteins

35
Q

What inhibitor can be used to give salbutamol chronically for asthma

A

theophylline

36
Q

What are the main properties of kinase linked receptors

A

hormone binds
triggers multiple parallel responses
relay proteins

37
Q

what are the mechanisms of nuclear receptors

A

steroid hormone crosses bilipid layer
binds to receptor
moves to nucleus
causes changes in gene transcription

38
Q

What are the 4 drug targets

A

receptors
enzymes
ion channels
carrier proteins

FoM (38 decks)

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