Agonists, Dose-Response Curves, and Partial Agonists

Question 1

What is EC50?

Answer 1

Agonist concentration that gives response that is 50% of max. response strength

Question 2

What is receptor occupancy (pAR)?

Answer 2

Proportion of receptors occupied by ligand

Question 3

What is the law of mass action?

Answer 3

Rate of reaction is proportional to product of concentrations of reactants

Question 4

What are the two assumptions of A + R AR?

Answer 4

Law of mass action applies

System at equilibrium - net rate of forward and reverse reactions is equal

Question 5

What is the dissociation equilibrium constant?

Answer 5

KA = (k-1)/(k+1)

Question 6

What is the Hill-Langmuir equation?

Answer 6

PAR = [A]/(KA+[A])

Question 7

What is the Hill-Langmuir equation rearranged to create a Hill plot?

Answer 7

log(PAR/(1-PAR)) = log[A] - log(KA)

Question 8

Give an example of one full agonist and one partial agonist of beta-adrenoceptors

Answer 8

Partial - prenalterol

Full - adrenaline

Question 9

Give an example of one full agonist and one partial agonist of mAChRs

Answer 9

Partial - pilocarpine

Full - acetylcholine

Question 10

Give an example of one full agonist and one partial agonist of H2 receptors

Answer 10

Partial - impromidine

Full - histamine

Question 11

What is efficacy?

Answer 11

Ability of agonist to activate receptor

Question 12

What is the del-Castillo and Katz mechanism?

Answer 12

A+R AR AR*