Essential Pharmacology Flashcards
What is the main criteria of a chemical messenger which acts on an intercellular receptor?
Must be lipid soluble
What are the four types of membrane receptors?
- Ionotropic receptors
- Receptors which function as enzymes
- Receptors which affect enzyme activity- Connected to enzyme but receptor itself is not enzyme
- G- Protein coupled receptor
What are ionotropic receptors?
Receptors which function as ion channels.
They have Fast EPSPs and IPSPs
How do G-Protein coupled receptors work?
Chemical messenger reaches receptor
Stimulates the alpha subunit of the G protein to regulate enzyme to produce second receptor. This second receptor regulates the activity of a second enzyme which allows the overall desired response.
For example, if the G protein is coupled to enzyme is adenylyl cyclase, it will increase/decrease production of cAMP as the second messenger which will activate/ inhibit the enzyme PKA, allowing it to phosphorylate proteins.
What are the cell’s sources of Calcium ions?
- Released from Endoplasmic reticulum (stimulated by IP3- or Ca2+)
- Extracellular sources entering via voltage or ligand gated Calcium channels
- Calcium remaining in cell as Calcium removal is inhibited
What is meant by the EC50 of a drug?
This is the log[drug] which occurs at half of the maximum response (i.e. when half of the receptor sites are saturated with the drug)
What would a high EC50 indicate about a drug?
It has a low affinity
What is meant by a drug’s ‘affinity’?
The strength of chemical attraction between drug and receptor.
What is meant by a drug’s ‘efficacy’?
This is a measure of how good the drug is at activating the receptor.
What is the difference between an agonist and an antagonist?
Agonists mimic the normal effect of a receptor
Antagonists block the normal effect of a receptor
