Schelegle E S, Carl M L, Coleridge H M, Coleridge J C, Green J F
Department of Human Physiology, University of California, Davis 95616.
J Appl Physiol (1985). 1993 May;74(5):2338-44. doi: 10.1152/jappl.1993.74.5.2338.
Acute inhalation of ozone induces vagally mediated rapid shallow breathing and bronchoconstriction. In spontaneously breathing anesthetized dogs, we attempted to determine whether afferent vagal C-fibers in the lower airways contributed to these responses. Dogs inhaled 3 ppm ozone for 40-70 min into the lower trachea while cervical vagal temperature was maintained successively at 37, 7, and 0 degrees C. At 37 degrees C, addition of ozone to the inspired air decreased tidal volume and dynamic lung compliance and increased breathing frequency, total lung resistance, and tracheal smooth muscle tension. Ozone still evoked significant effects when conduction in myelinated vagal axons was blocked selectively by cooling the nerves to 7 degrees C. Ozone-induced effects were largely abolished when nonmyelinated vagal axons were blocked by cooling to 0 degree C, breathing during ozone inhalation at 0 degree C being generally similar to that during air breathing at 0 degree C, except that minute volume and inspiratory flow were higher. We conclude that afferent vagal C-fibers in the lower airways make a major contribution to the acute respiratory effects of ozone and that nonvagal afferents contribute to the effects that survive vagal blockade.
急性吸入臭氧会引发迷走神经介导的快速浅呼吸和支气管收缩。在自主呼吸的麻醉犬中，我们试图确定下呼吸道传入迷走神经C纤维是否参与了这些反应。犬经下气管吸入3 ppm臭氧40 - 70分钟，同时将颈迷走神经温度依次维持在37、7和0摄氏度。在37摄氏度时，向吸入空气中添加臭氧会降低潮气量和动态肺顺应性，并增加呼吸频率、总肺阻力和气管平滑肌张力。当通过将神经冷却至7摄氏度选择性阻断有髓迷走神经轴突的传导时，臭氧仍会引发显著效应。当通过冷却至0摄氏度阻断无髓迷走神经轴突时，臭氧诱导的效应基本消除，在0摄氏度吸入臭氧期间的呼吸通常与在0摄氏度空气呼吸期间相似，只是分钟通气量和吸气流量更高。我们得出结论，下呼吸道传入迷走神经C纤维对臭氧的急性呼吸效应起主要作用，而非迷走神经传入纤维对迷走神经阻断后仍存在的效应有贡献。
