Kou Y R, Frazier D T, Lee L Y
Department of Physiology and Biophysics, University of Kentucky Medical Center, Lexington 40536.
Respir Physiol. 1989 Jun;76(3):347-56. doi: 10.1016/0034-5687(89)90075-3.
Our recent studies suggested that a nicotine-induced stimulation of afferent vagal C-fibers in the lungs was involved in eliciting the immediate cardiorespiratory responses to inhaling cigarette smoke. To examine this possibility, afferent impulses were recorded from vagal pulmonary C-fibers in 16 anesthetized, open-chest and artificially ventilated dogs, before and after four separate doses of nicotine (2.5, 5, 10 and 20 micrograms/kg) were injected into the right atrium. The base-line activity did not change after injection of isotonic saline. In contrast, nicotine stimulated 24 of 29 C-fibers: a burst of discharge was evoked immediately (1-2 sec) after the injection and usually lasted 3-8 sec. The peak responses of these pulmonary C-fibers to nicotine injections showed a dose-dependent relationship. In 17 C-fibers tested, the responses evoked by right atrial injection of 10 micrograms/kg of nicotine were similar to those evoked by delivery into the lungs of a single breath of smoke generated from cigarette with a high-nicotine content. Based upon these results, we conclude that nicotine alone stimulates vagal pulmonary C-fibers in a dose-dependent manner and this stimulant action of nicotine may play a part in eliciting the immediate reflex cardiorespiratory responses to inhalation of cigarette smoke.
我们最近的研究表明，尼古丁对肺部传入迷走神经C纤维的刺激参与了对吸入香烟烟雾的即时心肺反应的引发。为了检验这种可能性，在向16只麻醉、开胸并人工通气的狗的右心房注射四剂不同剂量（2.5、5、10和20微克/千克）的尼古丁之前和之后，记录了迷走神经肺C纤维的传入冲动。注射等渗盐水后基线活动没有变化。相比之下，尼古丁刺激了29根C纤维中的24根：注射后立即（1 - 2秒）引发一阵放电，通常持续3 - 8秒。这些肺C纤维对尼古丁注射的峰值反应呈剂量依赖性关系。在17根接受测试的C纤维中，右心房注射10微克/千克尼古丁所引发的反应与向肺部输送一口高尼古丁含量香烟产生的烟雾所引发的反应相似。基于这些结果，我们得出结论，尼古丁单独以剂量依赖性方式刺激迷走神经肺C纤维，并且尼古丁的这种刺激作用可能在引发对吸入香烟烟雾的即时反射性心肺反应中起作用。
