Mathew O P, Sant'Ambrogio F B, Sant'Ambrogio G
Respir Physiol. 1986 Oct;66(1):61-70. doi: 10.1016/0034-5687(86)90139-8.
We investigated the reflex effects of laryngeal cooling on posterior cricoarytenoid (PCA) muscle activity, breathing pattern, arterial blood pressure and heart rate. We performed experiments on 9 anesthetized, spontaneously breathing dogs. Laryngeal temperature was decreased by passing cold air through the functionally isolated larynx while the dog was breathing through a tracheostomy. Inspiratory and expiratory durations, esophageal pressure, peak PCA activity, heart rate and blood pressure did not change significantly during laryngeal cooling. Upon interruption of cold airflow, while the laryngeal temperature was returning to control values, we assessed PCA response to upper airway occlusion. At laryngeal temperatures of 20-25 degrees C the peak PCA activity during upper airway occlusion was approximately 2/3 of that observed at control temperature (approximately equal to 33 degrees C). This difference was abolished by topically applied anesthetics or by superior laryngeal nerve section. In addition, we recorded from 4 laryngeal mechanoreceptors stimulated by negative pressure; their response to upper airway occlusion was reduced to 1/2 by laryngeal cooling. These results indicate that laryngeal cooling has a marked depressive effect on the PCA response to collapsing pressure in the larynx, thereby compromising the mechanism subserving upper airway patency.
我们研究了喉部冷却对环杓后肌（PCA）活动、呼吸模式、动脉血压和心率的反射作用。我们对9只麻醉状态下自主呼吸的狗进行了实验。当狗通过气管造口呼吸时，通过功能隔离的喉部通入冷空气来降低喉部温度。在喉部冷却过程中，吸气和呼气持续时间、食管压力、PCA峰值活动、心率和血压均无显著变化。在中断冷气流、喉部温度恢复到对照值时，我们评估了PCA对上呼吸道阻塞的反应。在喉部温度为20 - 25摄氏度时，上呼吸道阻塞期间的PCA峰值活动约为对照温度（约33摄氏度）下观察到的值的2/3。局部应用麻醉剂或切断喉上神经可消除这种差异。此外，我们记录了4个受负压刺激的喉部机械感受器；喉部冷却使其对上呼吸道阻塞的反应降低至1/2。这些结果表明，喉部冷却对PCA对喉部塌陷压力的反应具有显著的抑制作用，从而损害了维持上呼吸道通畅的机制。
