A2 Agonists Flashcards
Ture or false agonists can be naturally occurring
True - the response for agonists can be excitatory or inhibitory
What does increase agonist conc do
increasing conc leads to larger & larger response until max response: Emax is reached
Linear plot of conc VS response produces what type of curve
rectangular hyperbola
Plotting the whole of a rectangular hyperbola on a semilog scale results in
an S shaped sigmoidal curve (w/ central portion linear) easier to read EC50
How would you determine receptor subtypes
by testing the rank order potency in receptors - if different tissue types result in different rank = subtypes
True or false: agonist conc curves can be used to calculate the affinity of a drug for its receptor
False - response is usually not proportional no. of occupied receptors
Define: Law of mass action
the rate of the chemical process is proportional to the concentration of the reacting substances
What happens to Kd as the affinity for the receptor increases
KD decreases
Describe Partial agonist
Have particularly low efficacies and cant produce the max response from the tissue no matter how high their conc
Can partial agonist reduce the action of full agoinsts
Yes - despite partial agonists have low efficacy it can occupy a large proportion of receptors therefore reducing action of full agonist
(partial: 100% occupancy vs full agonist: 20%)
what happens when partial agonist is applied in presence of full agonist
full + partial curve is displaced to the right + baseline is increased by partial –> shows partial is occupying large portion of receptors. Full agonist needs to displace large proportion to generate response
Describe Inverse agonist
has negative efficacy: reduces level of receptor activation (opposite effect of agonist)
drives Eq to left (R)
e.g. almost all H1 & H2 antishistamines are inverse a.
