What is the mechanism of action of atropine?

Atropine's primary mechanism of action is to block the effects of acetylcholine at muscarinic receptors. This blockade occurs at various sites in the body, particularly in the heart, smooth muscles, and glands, leading to a range of physiological responses. One significant application of atropine is to increase heart rate by preventing acetylcholine from exerting its slowing effect on the heart, which is particularly useful in treating bradycardia. Additionally, by inhibiting secretions in the respiratory system and reducing gastrointestinal activity, atropine can be employed preoperatively to minimize secretions during surgery.

In summary, the effectiveness of atropine in managing conditions related to excessive acetylcholine activity is tied directly to its ability to block muscarinic receptors, demonstrating a clear and well-defined pharmacological action.