Biochemical basis of drug action

Question 1

What are the 4 types of receptor classes

Answer 1

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

Question 2

What is an example of a ligand-gated ion channel

Answer 2

nicotinic ACh receptor (nAChr)

Question 3

what is an example of a G protein-coupled receptor

Answer 3

Muscarinic ACh receptor (mAChr)

Question 4

what is an example of a kinase-linked receptor

Answer 4

cytokine receptor

Question 5

what is an example of nuclear receptors

Answer 5

steroid hormone receptors

Question 6

What is the relative timescale for ligand gated ion channels mechanism

Answer 6

milliseconds

Question 7

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

Answer 7

seconds

Question 8

What is the mechanism for ligand-gated ion channels

Answer 8

ligand binds to receptor
ion channel opens
influx on ions

Question 9

How do agonists stimulate a response

Answer 9

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

Question 10

how do antagonists stimulate a response

Answer 10

bind to receptor
block action of biological molecule

Question 11

What are nicotinic acetylcholine receptors permeable to

Answer 11

Na+
K+
Ca2+

Question 12

What are the functions of ligand-gated ion channels

Answer 12

modulate fast synaptic excitation

Question 13

How are Ca2+ channels activated in neurotransmission

Answer 13

by excitation

Question 14

What causes vesicles to move down the pre-synaptic neuron

Answer 14

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

Question 15

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

Answer 15

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

Question 16

What drug acts as a full agonist at nicotinic acetylcholine receptors

Answer 16

nicotine

Question 17

what drug acts as a partial agonist at nicotinic acetylcholine receptors

Answer 17

varenicline

Question 18

How do partial agonists work

Answer 18

inhibits binding of biological molecule
binds to some receptors instead

Question 19

How can partial agonists be used to reduce drug craving

Answer 19

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

Question 20

What is the mechanism of G protein-coupled receptors

Answer 20

single peptide binds
initiates messenger system/cascade
causes cellular response

Question 21

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

Answer 21

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

Question 22

When is the enzyme adenylyl cyclase inactivated

Answer 22

GTP hydrolysed

Question 23

What is the result of adrenaline binding to B2-adrenoreceptors

Answer 23

bronchodilation

Question 24

How are signals amplified by G proteins

Answer 24

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

Question 25

What part of the autonomous nervous system is adrenaline part of

Answer 25

sympathetic

Question 26

What response does adrenoreceptor a1 cause

Answer 26

vasoconstriction of blood vessels

Question 27

what response does adrenoreceptor a2 cause

Answer 27

relaxation of the GI tract

Question 28

what response does adrenoreceptor B1 cause

Answer 28

increase heart rate increased cardiac muscle contraction

Question 29

what response does adrenoreceptor B2 cause

Answer 29

dilation of bronchi

Question 30

what response does adrenoreceptor B3 cause

Answer 30

thermogenesis in skeletal muscle

Question 31

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

Answer 31

want to activate specific receptors to get desired therapeutic effect

Question 32

which drug should be given for asthma

Answer 32

salbutamol only activates B2 only causes bronchodilation

Question 33

what happens a receptor is continuously activated by drugs

Answer 33

receptors break down less receptors on cell surface desensitisation

Question 34

How can drugs that stimulate receptors be given chronically

Answer 34

via enzymes that stop the amplification of G proteins

Question 35

What inhibitor can be used to give salbutamol chronically for asthma

Answer 35

theophylline

Question 36

What are the main properties of kinase linked receptors

Answer 36

hormone binds triggers multiple parallel responses relay proteins

Question 37

what are the mechanisms of nuclear receptors

Answer 37

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

Question 38

What are the 4 drug targets

Answer 38

receptors enzymes ion channels carrier proteins