Nakamura M, Haga T, Miyano M, Sasaki H, Takishima T
J Appl Physiol (1985). 1986 Nov;61(5):1677-85. doi: 10.1152/jappl.1986.61.5.1677.
The dose-response curves of the central and peripheral airways to intravenously injected nicotine were studied in 55 anesthetized dogs. With intact vagi, nicotine caused a dose-dependent increase in central airway resistance (Rc) similar to the increase in peripheral airway resistance (Rp) at concentrations ranging from 4 to 64 micrograms/kg. However, the responses of both Rc and Rp fell progressively when sequential doses of nicotine greater than 256 micrograms/kg were administered. With intact vagi and the administration of propranolol, there was a greater increase in Rp than in Rc at a nicotine dose of 64 micrograms/kg (P less than 0.05). With vagotomy, the responsiveness of both central and peripheral airways to nicotine decreased with doses of nicotine less than 64 micrograms/kg, but with doses of nicotine greater than 256 micrograms/kg the suppressive effect of nicotine on both Rc and Rp was less than that seen with intact vagi. Under conditions in which the vagi were cut and atropine administered, the responsiveness of nicotine was even further depressed. Combinations either of atropine and chlorpheniramine or atropine and phenoxybenzamine also completely blocked reactions to nicotine. Additionally reactions to nicotine were completely blocked by hexamethonium. These results suggest that nicotine increases both Rc and Rp mainly through a vagal reflex and stimulation of the parasympathetic ganglia.
在55只麻醉犬中研究了静脉注射尼古丁后中央气道和外周气道的剂量反应曲线。在迷走神经完整的情况下，尼古丁在4至64微克/千克的浓度范围内引起中央气道阻力（Rc）呈剂量依赖性增加，类似于外周气道阻力（Rp）的增加。然而，当给予大于256微克/千克的连续剂量尼古丁时，Rc和Rp的反应均逐渐下降。在迷走神经完整且给予普萘洛尔的情况下，在尼古丁剂量为64微克/千克时，Rp的增加大于Rc（P<0.05）。迷走神经切断后，当尼古丁剂量小于64微克/千克时，中央气道和外周气道对尼古丁的反应性均降低，但当尼古丁剂量大于256微克/千克时，尼古丁对Rc和Rp的抑制作用小于迷走神经完整时。在迷走神经切断并给予阿托品的情况下，尼古丁的反应性进一步降低。阿托品与氯苯那敏或阿托品与酚苄明的组合也完全阻断了对尼古丁的反应。此外，六甲铵完全阻断了对尼古丁的反应。这些结果表明，尼古丁主要通过迷走神经反射和刺激副交感神经节来增加Rc和Rp。
