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Curare is a common name for various plant extract alkaloid arrow poisons originating from Central and South America. These poisons function by competitively and reversibly inhibiting the nicotinic acetylcholine receptor (nAChR), which is a subtype of acetylcholine receptor found at the neuromuscular junction. This causes weakness of the skeletal muscles and, when administered in a sufficient dose, eventual death by asphyxiation due to paralysis of the diaphragm. According to pharmacologist Rudolf Boehm's 1895 classification scheme, the three main types of curare are: * tube or bamboo curare (so named because of its packing into hollow bamboo tubes; main toxin is D-tubocurarine). * pot curare (originally packed in terra cotta pots; main alkaloid components are protocurarine, protocurine, and protocuridine). Protocurarine is the active ingredient; protocurine is only weakly toxic, and protocuridine is not toxic. * calabash or gourd curare (originally packed into hollow gourds; main toxin is curarine). Of these three types, some formulas belonging to the tube curare are the most toxic, relative to their values.〔 ==History== Curare was used as a paralyzing poison by South American indigenous people. The prey was shot by arrows or blowgun darts dipped in curare, leading to asphyxiation owing to the inability of the victim's respiratory muscles to contract. The word 'curare' is derived from ''wurari'', from the Carib language of the Macusi Indians of Guyana.〔(Online Etymology Dictionary )〕 Curare is also known among indigenous peoples as Ampi, Woorari, Woorara, Woorali, Wourali, Wouralia, Ourare, Ourari, Urare, Urari, and Uirary. In 1596, Sir Walter Raleigh mentioned the arrow poison in his book ''Discovery of the Large, Rich, and Beautiful Empire of Guiana'' (which relates to his travels in Trinidad and Guayana), though the poison he described possibly was not curare.〔Carman J. A. ''Anaesthesia'' 1968, 23, 706.〕 In 1780, Abbe Felix Fontana discovered that it acted on the voluntary muscles rather than the nerves and the heart.〔The Gale Encyclopedia of Science. Third Edition.〕 In 1832, Alexander von Humboldt gave the first western account of how the toxin was prepared from plants by Orinoco River natives.〔()''Personal Narrative of Travels to the Equinoctial Regions of America, During the Year 1799-1804 — Volume 2'', Humboldt, Alexander von〕 During 1811–1812 Sir Benjamin Collins Brody (1783–1862) experimented with curare.〔''Phil. Trans''. 1811, 101, 194; 1812, 102, 205.〕 He was the first to show that curare does not kill the animal and the recovery is complete if the animal's respiration is maintained artificially. In 1825, Charles Waterton described a classical experiment in which he kept a curarized female donkey alive by artificial respiration with a bellows through a tracheostomy.〔(Arrow Poison to Surgical Muscle Relaxant )〕 Waterton is also credited with bringing curare to Europe.〔Reprinted in "Classical File", ''Survey of Anesthesiology'' 1978, 22, 98.〕 Robert Hermann Schomburgk, who was a trained botanist, identified the vine as one of the ''Strychnos'' genus and gave it the now accepted name ''Strychnos toxifera''.〔(Waterton and Wouralia. ''British Journal of Pharmacology'' (1999) 126, 1685–1689 )〕 George Harley (1829–1896) showed in 1850 that curare (''wourali'') was effective for the treatment of tetanus and strychnine poisoning.〔Paton A. ''Practitioner'' 1979, 223, 849〕〔(George Harley )〕 In 1857, Claude Bernard (1813-1878) published the results of his experiments in which he demonstrated that the mechanism of action of curare was a result of interference in the conduction of nerve impulses from the motor nerve to the skeletal muscle, and that this interference occurred at the neuromuscular junction.〔 From 1887, the Burroughs Wellcome catalogue listed under its 'Tabloids' brand name, tablets of curare at grain (price 8 shillings) for use in preparing a solution for hypodermic injection. In 1914, Henry Hallett Dale (1875–1968) described the physiological actions of acetylcholine.〔Dale H. H. ''J. Pharmac. Exp. Ther.'' 1914, 6, 147.〕 After 25 years, he showed that acetylcholine is responsible for neuromuscular transmission, which can be blocked by curare.〔Dale H. H. ''Br. Med. J.'' 1934, 1, 835〕 The best known and historically most important (because of its medical applications) toxin is d-tubocurarine. It was isolated from the crude drug — from a museum sample of curare — in 1935 by Harold King (1887–1956) of London, working in Sir Henry Dale's laboratory. He also established its chemical structure.〔King H. J. ''Chem. Soc''. 1935, 57, 1381; ''Nature, Lond''. 1935, 135, 469.〕 It was introduced into anesthesia in the early 1940s as a muscle relaxant for surgery. Curare is active — toxic or muscle-relaxing, depending on the intended use — only by an injection or a direct wound contamination by poisoned dart or arrow. It is harmless if taken orally〔〔(Curare - Chondrodendron tomentosum )〕 because curare compounds are too large and highly charged to pass through the lining of the digestive tract to be absorbed into the blood. For this reason, people can eat curare-poisoned prey safely. In medicine, curare has been superseded by a number of curare-like agents, such as pancuronium, which have a similar pharmacodynamic profile, but fewer side effects. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「curare」の詳細全文を読む スポンサード リンク
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