SfM - Pharmacology

Question 1

4 different types of plasma membrane receptors

Answer 1

• ionotropic (receptors act as ion channels - fast EPSP/IPSP)
• receptor/enzyme (receptors w/ intrinsic enzyme activity - tyrosine kinases - prolif/differ)
• receptor/kinase (receptors interact with JAK kinases - protein synthesis)
• metabotropic (receptors interact with G-proteins)

Question 2

what is a G-protein coupled receptor?

Answer 2

• receptor has 7 transmembrane spanning domains
• chemical signal binds outside cell and elicits signal transduction intracellularly (G-protein dissociates once messenger binds, regulates enzyme responsible for producing secondary messenger)

Question 3

what is a Gs receptor?

Answer 3

• messenger binding stimulates adenylyl cyclase

- produces cyclic AMP which regulates/activates kinases (PKA) - phosphorylates proteins/activates them

Question 4

what is a Gi receptor?

Answer 4

• messenger binding inhibits adenylyl cyclase/cAMP

- dephosphorylation that occurs stops protein function

Question 5

how is phospholipase C involved?

Answer 5

• there is a GpCR that is linked to PLC
• when messenger binds it activates PLC
• this produces 2 secondary messengers - IP3/DAG
• DAG activates protein kinase C
  IP3 causes release of Ca2+ from ER which indirectly activates protein lipase C

Question 6

what is Ca2+ role as a secondary messenger?

Answer 6

• Ca2+ directly affects target protein (PKC)
• binds to calmodulin which then activates target protein
• works via some other Ca2+ binding protein i.e troponin

Question 7

what are drugs?

Answer 7

• drugs are a chemical agent that effect biological systems

Question 8

what are drugs mechanism of action?

Answer 8

• drugs act by interacting with a binding site (mostly receptors)
• drug binding gives characteristic properties (drug binds to a specific site & exerts action giving a specific response)

Question 9

what is EC50?

Answer 9

half the maximal response

• can be used to quantify affinity/efficacy
  i. e low EC50 suggests high affinity and high efficacy

Question 10

define drug affinity

Answer 10

• how well does the drug bind to the receptor

Question 11

define drug efficacy

Answer 11

• how good is the drug at activating receptor/eliciting a response

Question 12

define agonist

Answer 12

• drug that binds to the receptor and produces an enhanced normal response
• mimic normal affect of receptor

Question 13

define antagonist

Answer 13

• antagonist binds to the same receptor & blocks the endogenous messenger from having an effect (block normal action of R)
• competitive antagonist - competes with agonist for binding site (require higher conc of substrate to elicit same response)

Question 14

what is a selective agonist?

Answer 14

• they can bind to and activate some receptors