Essential Pharmacology & Autonomic and Neuromuscular Pharmacology Flashcards
(48 cards)
Describe the basic functions of receptors.
Enable specificity, evoke an appropriate response.
What is the function of the G-protein receptor?
Regulate protein function
What is the largest class of receptor?
G-protein receptors
What is the secondary messenger commonly associated with the G-protein receptor?
cAMP - by the adenyl cyclase associated with the receptor or phospholipase C.
What is the function of G-protein receptors that are coupled to ion channels?
Evoke slow EPSPs or IPSPs.
What are the two main locations of receptors?
Transmembrane and intracellular.
Define agonist.
Mimic normal effect of the receptor.
Define antagonist.
Block normal action of receptor.
Describe the affinity and efficacy of agonists.
Full agonist = high affinity and high efficacy.
Partial agonist = high affinity and low efficacy.
Describe the affinity of antagonists.
High affinity and no efficacy.
Describe the relationship between the concentration of the agonist and the effect.
Increasing agonist con concentration, increases the response until drug binds and activates all receptors. The number of receptors are limited so the maximum saturated response will be reached.
Define affinity.
Does it bind receptor?
- Strength of chemical attraction between drug and receptor (lower EC50 = higher affinity)
How much of a drug would be required if it has higher affinity?
Less of the drug.
Where on the dose response curve would you find a curved for a drug with low affinity?
Shifted to the right (higher EC50).
Define efficacy.
Does it activate the receptor?
- how good the drug is at activating the receptor.
Where on the dose response curve would you find a curve for a drug with low efficacy?
Below the curve.
Compare efficacy in full and partial agonists.
Full agonist = High efficacy
Partial agonist = Low efficacy
Describe the process of transmembrane signalling (G-protein coupled receptors), giving two examples.
- Adenyl cyclase - produces cAMP and regulates PKA.
2. Phospholipase C - produces DAG and regulates PKC and IP3 that regulate calcium (secondary messenger)
List 5 transmembrane receptors.
- Enzyme-linked
- Ligand-gated ion channel
- G-protein coupled
- Voltage-gated
- Cytokine receptor
List three sources of intracellular calcium.
- Internal stores (via IP3 or Ca2+ stimulated release form endoplasmic reticulum)
- Outside cell (via voltage-gated or ligand-gated calcium channels)
- Via inhibition of calcium transport out of cell.
What are the effects of calcium?
- Directly effect target protein (e.g PKC)
- Bind to calmodulin which activated target.
- Via some other binding protein e.g troponin.
Where would you find the dose response curve for an agonist in presence of competitive antagonist.
Shifted to right (agonist less likely to bump into free receptors)
What are the potential sites of action for drugs to modulate synaptic transmission in ANS?
- Inhibit acetylcholine transport
- block voltage-gated Ca2+ ion channels
- block vessel fusion
- block ACh activated channel
- block non-depolarising nicotinic receptors
- block depolarising nicotinic receptors
How can postganglionic parasympathetic transmission be targeted?
Mimic (agonist) or block (antagonist) muscarinic receptors.
