19 - Pharmacology Flashcards
Examples of non-receptor targets of drugs
✦ Ion channels e.g. Ca2+ channels
✦ Enzymes e.g. cyclo-oxygenase
✦ Carrier molecules e.g. serotonin uptake
✦ DNA
Receptor definition
A receptor is a biological macromolecule or complex
that binds another molecule and initiates or modulates
signalling or effector activity within a cell.
Difference between agonist and antagonist
A ligand that binds to a receptor and activates it is an
agonist. A ligand that binds to a receptor without
activating it will act as an antagonist.
Beta-adrenoceptor
1)
2)
3)
1) GPCR
2) Responsive to adrenaline, noradrenaline
3) Stimulatory in some tissues (cardiac), inhibitory in others (bronchial muscle)
Artificial selective beta-adrenoceptor agonist
Isoprenaline
Artificial selective beta adrenoceptor antagonist
Propanolol
Timescale of ligand-gated ion channels
Miliseconds
Example of a ligand-gated ion channel
Nicotinic ACh receptor (Na+ channel)
Timescale of GPCR
Seconds
Example of a GPCR
Muscarinic ACh receptor
Kinase-linked receptors common substrates
Serine, tyrosine
Kinase-linked receptor timescale
Hours
Example of kinase-linked receptor
Cytokine receptors
Nuclear receptor timescale
Hours
Example of GPCR that isn’t on cell surface
Rhodopsin
Examples of effectors linked to GPCR
Ion channel, enzyme, transporter or regulator of gene transcription
Functional antagonism
Two different mechanisms oppose each other
Example of a tyrosine kinase receptor
Growth hormone receptor
Different types of nicotinic receptors
Nm are on muscles
Nn are in autonomic ganglia, CNS
Where are Beta1 adrenoceptors?
Mostly in heart
Where are beta2 adrenoceptors?
Bronchi, some blood vessels
Examples of diseases from receptor polymorphism
1)
2)
1) Androgen insensitivity - androgen receptor
2) Malignant hyperthermia - RyR r
