Atropine is classified as an anticholinergic drug. It is a potent derivative of belladonna, also known as deadly nightshade. Atropine is used as an antiarrhythmic drug, which counteracts irregular heart action. It is used as a preanesthetic drug to reduce secretions.
Antagonistic Action
According to RXList.com, atropine is a muscarinic receptor antagonist. Muscarinic refers to a toxic substance that slows the heart rate. Atropine antagonizes the muscarine-like actions of acetycholine, which is a chemical found in neurons (nerve cells). Acetycholine acts as a neurotransmitter, carrying information between two neurons. The receptors antagonized by atropine are located in the peripheral structures of the body, such as the endocrine glands, smooth muscle and the heart.
Temporary Increase in Heart Rate
According to CVPharmacology.com, atropine has a potent and prolonged effect on the heart, intestines and bronchial muscle. It causes an increase in heart rate in cases of bradycardia, which is a heart rate of less than 60 beats per minute in adults. Atropine inhibits the effects of excessive vagal or cranial nerve activation on the heart. Excessive vagal activation on the heart is manifest as sinus bradycardia and AV nodal block. AV nodal block is a delay in the conduction of electrical impulses at the AV node of the heart. Proper conduction is essential for a normal heart rhythm. Atropine can temporarily revert both bradycardia and AV nodal block by removing the vagal influences. Adequate doses of atropine prohibit asystole, which is the absence of a heart beat.
Tachycardia
Tachycardia, which is a rapid heart rate greater than 100 beats-per-minute in adults, is a side effect of chronic administration of therapeutic doses of atropine.
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