ORIGIN AND REGULATION OF VAGAL PREGANGLIONIC NEURON SUBTYPES CONTROLLING AIRWAY SMOOTH MUSCLE TONE

气道的主要作用是允许环境和肺之间的氧气和二氧化碳交换。然而，气道不仅仅是一系列静态的管道，而是它们的大小（或口径）会随着呼吸的变化而变化，从而调节气体交换以满足身体的需求。气道口径的调节主要通过气道壁肌肉张力的潜意识变化来实现。气道肌肉张力主要受自主神经系统的副交感神经分支的控制。两种不同类型的副交感神经支配气道：一种类型使用神经递质乙酰胆碱，引起气道肌肉收缩和气道收缩，而另一种类型使用一氧化氮，引起气道扩张。在多种炎性气道疾病中，气道口径的正常调节被改变。在哮喘和慢性阻塞性肺病（COPD）中，气道肌张力增加（气道收缩），这损害了气体的正常运动，并导致疾病的发病率和死亡率。越来越多的证据表明，气道肌张力过高可能部分是由于支配气道的收缩或舒张副交感神经功能障碍所致。然而，目前很少有人知道副交感神经通路调节气道口径。因此，全面了解控制气道平滑肌张力的机制对于充分理解自主神经功能障碍在阻塞性气道疾病发病机制中的可能作用至关重要。该基金的目的是更好地确定脑干中气道副交感神经的生理和解剖特性。

The primary role of the airways is to allow the exchange of oxygen and carbon dioxide between the environment and the lungs. However, the airways are not merely a series of static tubes, but rather their size (or caliber) is subject to breath-by-breath alterations, thereby regulating gas exchange to match the body's demands. Regulation of airway caliber is achieved largely by subconscious changes in the tone of the muscle lining the airway wall. Airway muscle tone is primarily under the control of the parasympathetic division of the autonomic nervous system. Two distinct types of parasympathetic nerves innervate the airways: One type employs the neurotransmitter acetylcholine which causes airway muscle to contract and the airways to constrict, while the other type employs nitric oxide which evokes airway dilatation. The normal regulation of airway caliber is altered in a variety of inflammatory airways diseases. In asthma and chronic obstructive pulmonary disease (COPD) there is an increase in airway muscle tone (airway constriction) which compromises the normal movement of gasses and contributes to the morbidity and mortality of the diseases. There is a growing body of evidence to suggest that exaggerated airway muscle tone may in part result from dysfunction of either the contractile or relaxant parasympathetic nerves innervating the airways. However, at present very little is known about the parasympathetic pathways regulating airway caliber. A complete understanding of the mechanisms controlling airway smooth muscle tone is therefore essential to fully understanding possible role of autonomic dysfunction in the pathogenesis of obstructive airways diseases. The aim of this grant is to better define the physiological and anatomical properties of airway parasympathetic nerves in the brain stem.