Essential Pharmocology Flashcards
Describe intracellular receptors and name some examples
As the receptors are inside the cell, only lipophilic molecules can act as messengers. The messenger dissociates from the binding protein and diffused into the cell. It can interact with DNA and act as transcription factors to turn genes on and off. Such as steroid hormones.
NO can bind to soluble guanylyl cyclase to generate cyclic GMP as a second messenger which regulates cell activity.
Name the four type of plasma membrane receptors and describe their function
Ionotropic receptors are a receptor and ion channel complex and can be used in nerve potentials. (Fast E and IPSP)
Receptors that function as enzymes so have intrinsic enzyme activity. Also receptors that directly alter an enzymes activity but the enzyme is another protein.
G protein coupled receptors.
Integrin receptors that interact with the cytoskeleton.
How do G protein coupled receptors work?
When the receptor is activated the G protein is split up and the alpha G protein modulates the activity of a molecule. They can also produce a cascade of second messengers.
Give two examples of substances that G proteins couple to and what effect this has
They can couple to adenylyl cyclase which produces cAMP. The cAMP regulates the activity of PKA. PKA can then go and phosphorylate and regulate protein function.
They can couple to phospholipase C which produces two secondary messengers. Diacylglycerol which activates PKC which is sensitive to calcium and phosphorylates substances. Inositol triphosphate activates PKC and releases calcium from internal store (duo effect)
What sources of calcium are there?
From internal stores via IP3-
Calcium stimulated release from ER.
From outside the cell via voltage gated or ligand gated channels.
Via inhibition of calcium transport out of the cell.
What are some effects of calcium in the body?
It directly affects target proteins (PKC).
It can bind to calmodulin which then activates target protein (camKinase).
Works via some other calcium binding protein such as troponin.
Define pharmacology
The study of the way chemical agents affect the biological system.
What is EC50 and what does it indicate?
It is the concentration of drug that gives 50% of the maximum response. A low EC50 indicates high affinity.
What is efficacy?
It is determined by how good the drug is at activating the receptor. (Partially activated receptors)
