Which statement best describes receptor reserve?

Which statement best describes receptor reserve?

• A. It implies that all receptors must be occupied for a maximal effect
• B. It means a maximal effect can occur without occupying all receptors
• C. It prevents pharmacological antagonists from affecting response
• D. It only applies to reversible antagonists

Answer: (B)

Receptor reserve means that not all receptors need to be occupied to achieve a full cellular response. Because the signaling system can amplify a small number of receptor activations, a maximal effect can occur even when only a fraction of receptors are bound by the drug. That makes the statement about achieving maximal effect without occupying all receptors the best description. The idea contrasts with thinking that every receptor must be engaged to get a maximal response. It also notes that antagonists can still influence the system by reducing receptor occupancy or shifting the response, and it isn’t limited to reversible antagonists—the concept is about how much receptor engagement is necessary for a full effect, regardless of the antagonist’s reversibility.

Receptor reserve means that not all receptors need to be occupied to achieve a full cellular response. Because the signaling system can amplify a small number of receptor activations, a maximal effect can occur even when only a fraction of receptors are bound by the drug. That makes the statement about achieving maximal effect without occupying all receptors the best description.

The idea contrasts with thinking that every receptor must be engaged to get a maximal response. It also notes that antagonists can still influence the system by reducing receptor occupancy or shifting the response, and it isn’t limited to reversible antagonists—the concept is about how much receptor engagement is necessary for a full effect, regardless of the antagonist’s reversibility.