ICU Primary PrepCast #Epi 91 - ICU Primary Snippet 34 - Receptors - Agonist, Partial agonist and Inverse agonist
May 19, 2024
Discover the mechanisms of receptors and ligand interactions, including distinctions between internal and cell surface receptors. Explore receptor classification, drug properties, and the impact on receptor responses. Learn about terms like efficacy, affinity, potency, and different types of ligands and antagonism.
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Two Main Receptor Classes
- Receptors are proteins that bind ligands to trigger biochemical responses via intracellular or cell-surface mechanisms.
- Internal receptors alter gene transcription while cell-surface receptors use ion channels, G proteins, or enzymes to signal.
Efficacy, Affinity, Potency Defined
- Efficacy, affinity and potency are distinct properties: efficacy is max effect, affinity is binding strength, potency is amount needed for effect.
- EC50 and KD quantify potency and affinity respectively, and potency depends on both affinity and coupling efficiency.
Two-State Receptor Model
- The two-state receptor model posits receptors flip between inactive and active states; ligands shift this equilibrium.
- Constitutive activity means some receptors signal without ligand, affecting how ligands behave pharmacologically.