Physiology and Pharmacology 1: (Evans)

Question 1

Occupancy equation

Answer 1

receptors occupied / total number of receptors

Question 2

How can occupancy be measured directly? Method?

Answer 2

Radioligand binding (radiolabelled agonist)

Method
- Prepare cells or membranes e.g. guinea pig ileum - detergent treatment and cetrifugation

• Aliquot out cells/membranes to filters
• Add radiolabel to samples/filters at different concentrations and equilibrate
• When equilibrated, remove unbound drug by filtration
  (bound drug remains attached)
• Count radioactivity of filter

Question 3

drug graphs

Answer 3

look at radio ligand binding curves

• non-specific binding
• semi-log plots

Question 4

Specific binding = ?

Answer 4

specific binding = total bound - non-specific

Question 5

What is Mass Action?

Answer 5

RATE of a reversible chemical reaction is proportional to the product of the concentration of the reactants

Question 6

Explain Model for drug-receptor binding? forward rate / backward rate + equilibrium

this might be pointless

Answer 6

Agonist + Receptor – K + 1 –> Agonist-receptor complex

Agonist + Receptor

Question 7

What is the dissociation constant?

Answer 7

Kd = agonist conc. required to occupy 50% of the receptors