Receptors and the Effects of Drugs Flashcards
Give an example of an effect of cocaine (on the molecular level).
Blocking the noradrenaline transporter.
List 2 ways by which drugs block effects by binding to receptors.
1 - Antagonism.
2 - Desensitisation.
Describe the patch-clamp technique to measure ionic currents from a receptor.
1 - A micropipette filled with an electrolyte is brought into contact with the receptor.
2 - An electrode is inserted into the micropipette.
3 - The current is amplified and visualised.
What is the effect of a neutral antagonist on a dose / response curve?
A flat line at 0 response.
What drugs produce a negative response (on a dose / response curve)?
Inverse agonists.
What type of receptor is the GABA-A receptor?
A ligand-gated chloride ion channel.
What effect do benzodiazepine agonists have on GABA-A receptors?
They bind to the GABA-A allosteric site to increase the affinity of GABA for GABA-A receptors.
List 2 benzodiazepine receptor (GABA-A allosteric site) ligands.
1 - Diazepam.
2 - Lorazepam.
Give an example of a class of drug that is an inverse agonist for benzodiazepine receptors (GABA-A allosteric sites).
Beta-carbolines.
Give an example of a drug that is an antagonist for benzodiazepine receptors (GABA-A allosteric sites).
Flumazenil.
To which receptor does atropine bind?
What is its effect?
- Muscarinic acetylcholine receptors.
- Competitive antagonistic effect.
To which receptor does propranolol bind?
What is its effect?
- Beta adrenoceptors.
- Competitive antagonistic effect.
What is the effect of a competitive antagonist on a dose / response curve?
A parallel shift to the right.
What is the effect of a non-competitive antagonist on a dose / response curve?
Reduces the height (max response) of the curve.
To which receptor does phenoxybenzamine bind?
What is its effect?
- Alpha adrenoceptors.
- Irreversible antagonistic effect.
List 5 types of antagonism.
1 - Competitive antagonists.
2 - Irreversible antagonists.
3 - Allosteric antagonists.
4 - Channel blockers.
5 - Physiological antagonists.
To which receptor does fulvestrant bind?
What is its effect?
- Oestrogen receptors.
- Degrades the receptor.
To which receptor does gallamine bind?
What is its effect?
- The muscarinic receptor allosteric site.
- Antagonistic effect.
To which receptor does phencyclidine bind?
What is its effect?
- NMDA receptors.
- Block the channel to prevent passage of ions (a channel blocker).
How are physiological antagonists different from other conventional antagonists?
They antagonise the physiological effect of some agonists, but are different in that they achieve this via a different mechanism.
Why is adrenaline said to be a physiological antagonist?
Because it has anti-histaminergic action despite not being a ligand for the histamine receptor.
What are endocrine disruptors?
Give an example of how some might work.
- A class of physiological antagonist.
- Some inhibit conjugation reactions.
Define desensitisation.
Where prolonged or repeated exposure to an agonist reduces the response to that drug.
What does controls heroin tolerance?
Adenylyl cyclase activity in the brain.
What mechanism might occur to cause desensitisation to some stimulants?
Inactivation of nicotinic receptors.
