NEURAL CONTROL RESPIRATORY MUSCLES DURING EXPIRATION

呼吸肌对呼气气流的主动控制 影响气体交换、肺排空程度， 呼吸的工作;可能有助于优化吸气肌肉 功能;在咳嗽和说话时很重要。 呼气时间和流速的改变发生在 对缺氧、高碳酸血症和运动的反应，以及疾病 例如哮喘、慢性阻塞性肺病和睡眠 呼吸暂停 延髓和脑桥呼吸系统的研究进展 研究中心认为，神经生理学上的呼气可能包括 两个不同的阶段。 在拟议的研究中，我们将重点关注 腹部、胸部和 上呼吸道肌肉在这些期间主动调节呼气 两个阶段。 具体来说，在麻醉的狗和猫，我们将1） 检查多个腹部和胸部 呼气肌在休息期间以协调的方式起作用， 刺激呼吸; 2）研究晚期 上述肌肉的呼气活动和早期呼气 胸吸气肌的活动; 3）评估程度 上呼吸道扩张器和收缩器被附接到该上呼吸道扩张器和收缩器 在到期的两个阶段期间活跃，以及如何操作 通过呼吸刺激进行修改; 4）记录来自单个 运动单位的选择呼吸肌，并检查如何 不同的运动单位亚群在呼气期间放电;以及5） 评估呼气电活动与 上述肌肉和肌肉的机械后果 收缩，包括肌肉长度的呼吸变化， 呼气流速和呼吸压力。 研究将 在正常呼吸期间进行，当呼吸受到刺激时， 高碳酸血症和缺氧，以及随后的支气管收缩; 此外，我们将评估不同的化学感受器的作用， 机械感受器在调节这些反应中发挥作用 刺激。 最后，在长期仪器清醒的猫，我们将 分析从几个腹部记录的呼气活动， 胸部和上呼吸道肌肉，以1）确保结论 来自麻醉动物的研究， 受麻醉效果的影响，以及2）评估效果 姿势的自发变化对呼吸肌活动的影响 在呼气期间。

Active control of expiratory airflow by the respiratory muscles influences gas exchange, the degree of emptying of the lungs, and the work of breathing; may help optimize inspiratory muscle function; and is important during coughing and speech. Alterations in expiratory timing and velocity of flow occur in response to hypoxia, hypercapnia and exercise, and in diseases such as asthma, chronic obstructive pulmonary disease and sleep apnea. Recent studies of medullary and pontine respiratory centers suggest that neurophysiologically expiration may consist of tow distinct phases. In the proposed studies we will focus on the peripheral mechanisms by which abdominal, thoracic and upper airway muscles actively modulate expiration during these two phases. Specifically, in anesthetized dogs and cats we will 1) examine the manner in which multiple abdominal and thoracic expiratory muscles act in a coordinated fashion during resting and stimulated breathing; 2) study the relationship between the late expiratory activity of the above muscles and the early expiratory activity of the thoracic inspiratory muscles; 3) assess the extent to which upper airway dilators and constrictors are reciprocally active during the two phases of expiration, and how this os modified by respiratory stimuli; 4) record activity from single motor units of selected respiratory muscles, and examine how different motor unit subpopulations fire during expiration; and 5) assess the relationship between expiratory electrical activity of the above muscles and the mechanical consequences of muscle contraction, including respiratory changes in muscle length, expiratory flow rates and respiratory pressures. Studies will be performed during eupnea, when breathing is stimulated by hypercapnia and hypoxia, and following bronchoconstriction; in addition we will assess the roles that different chemoreceptors and mechanoreceptors play in mediating the responses to these stimuli. Finally, in chronically instrumented awake cats we will analyze expiratory activity recorded from several abdominal, thoracic and upper airway muscles to 1) ensure that conclusions derived from studies in anesthetized animals are not unduly influenced by the effects of anesthesia, and 2) assess the effects of spontaneous changes in posture on respiratory muscle activity during expiration.