antagonists

Question 1

what is a competitive antagonist

Answer 1

where the agonist and antagonist bind to the same site

Question 2

how can a competitive antagonist be overcome

Answer 2

by increasing the concentration of the agonist

Question 3

what is a non-compettive antagonist

Answer 3

binds to a different binding site of the receptor or acts irreversibly

Question 4

what are three features of the competitive agonism curve

Answer 4

• curve shifts to the right in a parallel fashion
  -there is no change in Emax
  -pD2 will decrease

Question 5

what are three features of the non-competitive agonism curve

Answer 5

• pD2 is not changed
• Emax decreases
  -curves will not be parallel

Question 6

what are the two factors that affect the ability to block response

Answer 6

• the relative affinity of the agonist and antagonist for the receptor
  -the relative concentrations of the agonist and antagonist

Question 7

what is the dose ratio

Answer 7

the fold of increase of agonist needed to achieve the same response at an antagonist concentration

Question 8

how can we work out the dissociation constant of the antagonist

Answer 8

sub the dose ratio into the gaddum-schild equation

Question 9

what are the three assumptions of the gaddum-schild eqation

Answer 9

-assumes simple competitive antagonism
-no assumptions about the number of receptors are made
-independent of agonists as long as they compete for the same receptor

Question 10

what does it mean when the dose ratio is 2

Answer 10

this means that it takes double the amount of agonist to overcome the antagonist

Question 11

when the dose ratio is 2, what will the -logKa be equal to

Answer 11

pA2

Question 12

what will pA2 always be

Answer 12

positive

Question 13

if the slope of a gaddum-schild plot = 1, what does this mean

Answer 13

simple antagonist