1.2 Drug , receptor interactions

Question 1

What do drugs bind to?

Answer 1

receptors enzymes, ion channels and carrier molecules

Question 2

Define agonist

Answer 2

– An agonist is a ligand (drug, hormone or neurotransmitter) that combines with receptors to elicit a cellular response

Question 3

Define antagonist

Answer 3

– An antagonist is a drug which blocks the response to an agonist

Question 4

What effect do drugs have on carriers?

Answer 4

Either transported in the place of the endogenous substrate or inhibit transport

Question 5

Why does NSAID stand for?

2) What is their target?
3) What effect would the drug have?

Answer 5

1) Non steroidal anti-inflammatory drugs (NSAIDs) e.g. ibuprofen and aspirin
2) the enzyme. Cyclooxygenase
3) inhibit enzyme, preventing conversion of arachidonic acid to prostoglandins which causes inflammation, pain and fever.

Question 6

What occurs to phospholipids in cell membrane following immune activation or cell injury?

Answer 6

Phospholipase A2 , converts it to arachidonic acid, then cycloxygenase converts it to porstoglandins which causes inflammation, pain and fever.

Question 7

orthosteric vs allosteric

Answer 7

orthosteric, which bind at the active site; and allosteric, which bind elsewhere on the protein surface

Question 8

What do bensodiazepines do?

2) Can effect of benzodiazepines always be seen?

Answer 8

1) allosterically inhibit GABA alpha receptors,

2) only when GABA is present

Question 9

tell me about histamine

Answer 9

an agonist that binds to H1 receptor in smooth muscle to increase blood flow

Question 10

What are the similatities and differences between receptors part of the same family but different sub-types?

2) Why do histamine receptors have in common?
3) What is their difference?

Answer 10

a) similar structures
B)differences in their pharmacological response due to different specificities for what activates or inhibits them and different signal transduction mechanisms
3) histamine is their agonist
4) have different antagonists

Question 11

What is an agonist of nicotinic-acetyl choline?

2) what is the effect?
3) What is an antagonist?
4) what is the effect?
5) describe structure of this receptor:

Answer 11

1) acetyl choline
2) muscle contraction
3) nicotine
4) muscle relaxation
5) • Pentermeric structure ( 2 beta, 2 alpha, 1 delta, 1 gamma) have a kink in it,

Question 12

ionotropic vs metabotropic

Answer 12

Ionotropic receptors form an ion channel pore. In contrast, metabotropic receptors are indirectly linked with ion channels on the plasma membrane of the cell through signal transduction mechanisms,

Question 13

e.g. metabotropic receptor?

Answer 13

G-protein receptor

Question 14

What G-protien linked receptor do these bind to and what is the affect:

1) epinephrine
2) salbutamol

Answer 14

• α/β adrenoceptors – epinephrine ( a naturally endogenous agonist)
• β2 adrenoceptors – salbutamol (used to treat asthma)

Question 15

What is the action of Gs protein ?

Answer 15

Activates adenylyl cyclase Activates Ca2+ channels

Question 16

What is the action of Gi protein ?

Answer 16

Inhibits adenylyl cyclase Activates K+ channels

Question 17

What is the action of Gq protein ?

Answer 17

Activates phospholipase C

Question 18

What G protein is coupled to

1) alpha 1 adrenoreceptors
2) alpha 2 adrenoreceptors
3) beta 1 adrenoreceptors
4) beta 2 adrenoreceptors
b) What effect do they have in the body when activated?

Answer 18

1) Gq, b)vasoconstriction
2) Gi b) autoinhibition of neurotransmitter release
3) Gs b) accelerated HR
3) Gs b) bronchodilation

Question 19

Give the 7 steps of a G protein coupled receptor going from inactive form to active then inactive again?

Answer 19

1. Unoccupied receptor does not interact with Gs protein
2. Hormone or neurotransmitter binds to receptor
3. Occupoed receptor changes shape and interacts with Gs protein
4. Gs protein release GDP and binds to GTP
5. Alpha subunit of Gs protein dissociates and activates adenylyl cyclase
6. Adenylyl cyclase catalyses formation of cAMP and PPi.
7. When hormone is no longer present, the receptor reverts to its resting state. GTP on the alpha subunit is hydrolysed to GDP, and adenylyl cyclase is deactivated.