"What are the differences between receptor agonists and receptor antagonists?"

Update Date: 2024-10-16 Source: Network

Difference Between Receptor Agonists and Antagonists

The primary distinction between receptor agonists and antagonists lies in the presence or absence of intrinsic activity. Receptors are macromolecular proteins that mediate cellular signal transduction. For both receptor agonists and antagonists to exert their effects, they must bind to receptors, which requires two factors: affinity and intrinsic activity.

1. Receptor Agonists

Receptor agonists are drugs that possess both affinity and intrinsic activity. Upon binding to receptors, they activate the receptors to elicit a response. However, the effects of receptor agonists are not necessarily positive. For instance, β-receptor agonists can accelerate heart rate, whereas M-cholinergics can slow it down.

2. Receptor Antagonists

Receptor antagonists are drugs that possess affinity but lack intrinsic activity. When bound to receptors, they do not elicit a corresponding response, thereby blocking the effects of receptor activation. Nonetheless, receptor antagonists are not entirely negative. For example, atropine, an M-cholinergic receptor antagonist, can alleviate vagal and cardiac inhibition, increase heart rate, contractility, and stimulate the respiratory center.

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