Pharmacology

Question 1

What are adrenoceptors?

Answer 1

GDPRs activated by adrenaline/noradrenaline

Question 2

The potency of agonists in alfa and beta-adrenoceptors

Answer 2

• ⍺-adrenoceptor: noradrenaline > adrenaline > isoprenaline
• β-adrenoceptor: isoprenaline > adrenaline > noradrenaline

Question 3

What do each adrenoreceptor works and do?

Answer 3

GPCR adrenoceptor subtypes

• β1: coupled with Gs → stimulation of adenylyl cyclase → increase heart rate and force of contraction
• β2: coupled with Gs → stimulation of adenylyl cyclase → relaxation of bronchial and vascular smooth muscle
• ⍺1: coupled with Gq → stimulation of phospholipase C → contraction of vascular smooth muscle
• ⍺2: coupled with Gi → inhibition of adenylyl cyclase → inhibition of NA release

Question 4

What does each muscarinic cholinoceptors subtypes work and do?

Answer 4

• M1: coupled with Gq → stimulation of phospholipase C → increases stomach acid secretion
• M2: coupled with Gi → inhibition of adenyl cyclase; opening of K+ channels → decreases heart rate
• M3: coupled with Gq → stimulation of phospholipase C → increases secretion of saliva and contraction of visceral smooth muscle in the bronchioles. Vascular smooth muscle indirectly relaxed via NO

Question 5

How do you block cholinergic transmission?

Answer 5

• Depolarization block - high concentration of agonists
• Competitive antagonism
• Non-competitive antagonism

Question 6

What is the drug action of Cocaine?

Answer 6

• Blocks U1, increasing the concentration of NA in the synaptic cleft, resulting in increased adrenoreceptor stimulation
• Peripheral actions cause vasoconstriction (⍺1 stimulation) and cardiac arrhythmias (β1 stimulation)

Question 7

What is the drug action of Amphetamine?

Answer 7

• Substrate for U1, enters NA terminal where it inhibits MAO, enters the synaptic vesicle and displaces NA into the cytoplasm
• NA exits the terminal on U1 and accumulates in the synaptic cleft causing increased adrenoceptor stimulation

Question 8

What is the drug action of Prazosin?

Answer 8

• Selective, competitive antagonist of ⍺1
• Vasodilator, anti-hypertensive

Question 9

What is the drug action of Atenolol?

Answer 9

• Selective, competitive antagonist of β1
• Anti-anginal, anti-hypertensive

Question 10

What is the drug action of Salbutamol?

Answer 10

• Selective antagonist at β2 (does not block ⍺1, ⍺2 or β1)
• Bronchodilator in asthma

Question 11

What is the drug action of Atropine?

Answer 11

• Competitive antagonist of muscarinic ACh receptors
• Block all muscarinic receptors with equal affinity
• Widespread effects - blockade of parasympathetic division
• Used to reverse bradycardia following MI and in anticholinesterase poisoning