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1-Methyl-2-(3-pyridyl)pyrrolidine; a poisonous volatile alkaloid derived from tobacco (Nicotiana spp.) and responsible for many of the effects of tobacco; it first stimulates (small doses), then depresses (large doses) at autonomic ganglia and myoneural junctions; its principal urinary metabolite is cotinine. N. is an important tool in physiologic and pharmacologic investigation, is used as an insecticide and fumigant, and forms salts with most acids. SEE ALSO: tobacco. [Nicotiana, genus name of botanical source, + - ine] N. in inhaled tobacco smoke or in smokeless tobacco applied to buccal or nasal mucosa enters the circulation within seconds, causing an increase in heart rate, ventricular stroke volume, and myocardial oxygen consumption, as well as euphoria, heightened alertness, and a sense of relaxation. N. use is powerfully addictive, readily leading to habituation, tolerance, and dependency. Withdrawal from n. causes restlessness, irritability, anxiety, difficulty concentrating, and craving for n.. Addiction to n. is the reason for most tobacco use and is thus directly responsible for the resulting morbidity and mortality.

nic·o·tine 'nik-ə-.tēn n a poisonous alkaloid C₁₀H₁₄N₂ that is the chief active principle of tobacco and that is used as an insecticide

Ni·cot nē-kō Jean (1530?-1600)

French diplomat. While French ambassador to Portugal, Nicot introduced tobacco to France by sending tobacco seeds as a gift to the French court in 1560. Linnaeus named the plant genus Nicotiana in his honor in 1753.

a poisonous alkaloid derived from tobacco, responsible for the dependence of regular smokers on cigarettes. In small doses nicotine has a stimulating effect on the autonomic nervous system, causing in regular smokers such effects as raised blood pressure and pulse rate and impaired appetite. Large doses cause paralysis of the autonomic ganglia. Nicotine replacement therapy (nicotine products formulated as chewing gum, skin patches, nasal sprays, etc.) is used as an aid to stop smoking.