Why is it important to understand receptors? Give 4 reasons.
1)Pharmaceutical industry and development: 34 of the top 100 drugs on the market target G-protein couples receptors
2)Physiology of endogenous transmitters: Transmitters and hormones act primarily upon receptor targets
3)Chemical toxicity: Many toxic mechanisms are receptor mediated
4)Viral toxicity: Viruses and other microorganisms can target receptors
What is an agonist?
Drugs that occupy receptors and activate them
What is an antagonist?
Drugs that occupy receptors but do not activate them, antagonists block receptor activation by agonists
What is a partial agonist?
Drugs that can occupy receptors and activate them but not to the extent of an agonist
A picture demonstrating the agonist having both affinity and efficacy:
Statement: Most agonists bind irreversibly to their receptors.... Is this true?
FALSE
-Most agonists bing reversibly to their receptors and then dissociated when unneeded
Why is the binding reversible?
Weak bonds
Name the 4 main bonds and describe their strengths and dissociations
Reversible binding of an agonist to a receptor is governed by what law?
Law of mass action
Picture demonstrating how reversible binding is dependent on concentration of the reactants involved
What is the Bmax?
The maximum amount of receptor binding
Each drug has its own what value?
Kd value
What is Kd?
Kd (Affinity) is the ability of a drug molecule to bind to a receptor site: Concentration of the drug where 50% of max number of receptors are bound by the drug
Kd is inversely correlated with affinity. The lower the Kd, the higher the affinity
What is Efficacy?
Refers to the effect of the drug/ the biological effect, the more effect the drug has the more efficacious. e.g. increase in heart rate
Picture outlining efficacy:
