NEU 365D Lecture Notes - Lecture 12: Receptor Antagonist, Gaba Receptor, Picrotoxin
Document Summary
Antagonist - no efficacy (doesn"t produce a functional effect after it binds) - sometimes with high affinity. Competitive - compete with agonists & endogenous ligands for binding to the same specific sites on receptors. Shift agonist concentration-response curves ((apparent) ec 50 ) to the right. Doesn"t affect maximal possible response (just takes higher concentrations of agonist) Ex: atropine - muscarinic subtype of ach receptor. Irreversible - compete for same site as agonists. Bind so tightly/covalently sites are no longer available for agonists to bind. Decrease the maximal possible response to agonists. Ex: 10 receptors irreversibly bind 4. Non-competitive - bind to distinct sites on receptor that that of the agonist. Doesn"t affect agonist ec 50 (e. g. channel blockers) Ex: gaba receptor - picrotoxin (ptx) binds in the channel (in the pore) Even with gaba binding no current. Distinguish from irreversible: wait for non-competitive antagonist to wash out the response curve should go back up.
