Skip to main content

atropine

atropine is an alkaloid derived from the solanaceous plants Atropa belladonna (deadly nightshade), Hyoscyamus niger (black henbane), and Datura stramonium (thornapple). These plants contain a mixture of two closely related alkaloids, hyoscyamine and hyoscine; atropine is a mixture of two isomers of hyoscyamine. In 1867, von Bezold found that atropine blocked the slowing of the heart caused by vagal stimulation. We now know that atropine blocks the action of the neurotransmitter acetylcholine at all the nerve endings where the membrane receptors are of the so-called muscarinic type. This includes those of the parasympathetic nervous system in the heart, glandular tissue, and smooth muscle. Thus atropine causes a rise in heart rate and inhibits secretions (for example of saliva, causing a dry mouth, and of the digestive enzymes). It also relaxes smooth muscle in the gastrointestinal tract, the urinary bladder, and the bronchial trees, by preventing the effects of the normal background discharge of parasympathetic neurons to these organs.

The central nervous system also contains muscarinic receptors. Blockade of these by atropine leads to restlessness and mental excitement, and can improve the rigidity and tremor characteristic of Parkinson's disease. Large doses of atropine can cause hallucination.

Long-lasting pupillary dilation results if atropine drops are placed in the eye. The iris has both circular and radial muscles, and the balance between the tonic activities of these two muscle groups controls the pupil diameter. The circular muscle is under parasympathetic control, so when the transmitter, acetylcholine, is blocked with atropine, the pupil will dilate. It is told that Spanish ladies put atropine drops in their eyes for the allure given by large, black pupils: hence the name belladonna — ‘fine lady’.

Alan W. Cuthbert


See also autonomic nervous system; neurotransmitter; membrane receptors.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"atropine." The Oxford Companion to the Body. . Encyclopedia.com. 23 Jan. 2017 <http://www.encyclopedia.com>.

"atropine." The Oxford Companion to the Body. . Encyclopedia.com. (January 23, 2017). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/atropine

"atropine." The Oxford Companion to the Body. . Retrieved January 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/atropine

atropine

atropine (ăt´rəpēn, –pĬn), alkaloid drug derived from belladonna and other plants of the family Solanaceae (nightshade family). Available either as the tincture or extract of belladonna, or as the pure substance atropine sulfate, it is a depressant of the parasympathetic nervous system. It has some chemical similarity to the body substance acetylcholine and interferes with nerve impulses transmitted by that substance. Atropine produces rapid heart rate, dilated pupils, dry skin, and anesthetizes the nerve endings in the skin. Because it relaxes smooth muscle and suppresses gland and mucous secretions, it has been used to treat peptic ulcer by reducing the production of stomach acid. Atropine is given before general anesthesia to keep the air passages clear and is an ingredient in various preparations for symptomatic relief of colds and asthma. It also acts as an antidote in poisoning from such agents as mushrooms, morphine, prussic acid, and nerve gas, but overdosage causes delirium, convulsions, and coma. A related alkaloid, scopolamine, is used mainly as a sedative.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"atropine." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 23 Jan. 2017 <http://www.encyclopedia.com>.

"atropine." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (January 23, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/atropine

"atropine." The Columbia Encyclopedia, 6th ed.. . Retrieved January 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/atropine

atropine

atropine (at-rŏ-peen) n. an antimuscarinic drug extracted from belladonna. Atropine is used as a mydriatic (see cycloplegia, mydriasis). It is also used in surgery (as premedication and to reverse the action of muscle relaxants) and occasionally to relieve gut spasms. Trade names: Isopto Atropine, Minims Atropine Sulphate.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"atropine." A Dictionary of Nursing. . Encyclopedia.com. 23 Jan. 2017 <http://www.encyclopedia.com>.

"atropine." A Dictionary of Nursing. . Encyclopedia.com. (January 23, 2017). http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/atropine

"atropine." A Dictionary of Nursing. . Retrieved January 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/atropine

atropine

atropine Poisonous alkaloid drug (C17H23NO3N) obtained from certain plants such as Atropa belladonna (deadly nightshade). Atropine is used medicinally to regularize the heartbeat during anaesthesia, to dilate the pupil of the eye and to treat motion sickness.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"atropine." World Encyclopedia. . Encyclopedia.com. 23 Jan. 2017 <http://www.encyclopedia.com>.

"atropine." World Encyclopedia. . Encyclopedia.com. (January 23, 2017). http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/atropine

"atropine." World Encyclopedia. . Retrieved January 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/atropine

atropine

atropine A poisonous crystalline alkaloid, C17H23NO3. It can be extracted from deadly nightshade and other solanaceous plants and is used in medicine to treat colic, to reduce secretions, and to dilate the pupil of the eye.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"atropine." A Dictionary of Biology. . Encyclopedia.com. 23 Jan. 2017 <http://www.encyclopedia.com>.

"atropine." A Dictionary of Biology. . Encyclopedia.com. (January 23, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/atropine-0

"atropine." A Dictionary of Biology. . Retrieved January 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/atropine-0

atropine

atropine alkaloid poison from deadly nightshade. XIX. f. modL. atropa deadly nightshade, fem. f. Gr. Átropos (‘Inflexible’) name of one of the Fates, f. A-4 + trópos turn; see TROPE, -INE5.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"atropine." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. 23 Jan. 2017 <http://www.encyclopedia.com>.

"atropine." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. (January 23, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/atropine-0

"atropine." The Concise Oxford Dictionary of English Etymology. . Retrieved January 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/atropine-0

atropine

at·ro·pine / ˈatrəˌpēn/ • n. Chem. a poisonous alkaloid compound, C17N23NO3, found in deadly nightshade and related plants, and used in medicine.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"atropine." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 23 Jan. 2017 <http://www.encyclopedia.com>.

"atropine." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (January 23, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/atropine

"atropine." The Oxford Pocket Dictionary of Current English. . Retrieved January 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/atropine

atropine

atropine A substance that, by competing with acetylcholine for post-synaptic membrane receptor sites, inhibits the passage of nerve impulses across a synapse.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"atropine." A Dictionary of Zoology. . Encyclopedia.com. 23 Jan. 2017 <http://www.encyclopedia.com>.

"atropine." A Dictionary of Zoology. . Encyclopedia.com. (January 23, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/atropine

"atropine." A Dictionary of Zoology. . Retrieved January 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/atropine