PHYSIOLOGY OF MOTOR UNITS IN A HUMAN UPPER AIRWAY MUSCLE

鼻、口、舌和喉的上呼吸道肌肉控制 呼吸气流阻力，并有节奏地收缩， 呼吸了尽管它们的重要性，关于生理学的信息 上呼吸道运动单位的特性及其在上呼吸道运动分级中的作用 肌肉力量不可用。- 拟议的研究旨在 提供有关鼻神经生理学的基本信息， 健康人受试者的扩张肌运动神经元。鼻 选择扩张肌作为实验模型，因为它涉及 在控制鼻气道的逐个呼吸直径时， 在人类中很容易接触到，它对反射介导的 以类似于上呼吸道肌肉的方式进行呼吸刺激， 喉咙舌头和脸具体目标包括：（1）估计 鼻扩张肌中的运动单位数量; 2）确定鼻扩张肌中的 鼻扩张器运动神经元池的行为符合尺寸 原则，如发生在肢体肌肉; 3）确定的贡献， 速率调节和运动单位募集到肌肉的分级 力; 4）确定神经驱动与 鼻扩张肌，以及这些肌肉在鼻扩张过程中产生的力。 有节奏的，不自主的收缩;并估计相对 运动单位募集和速率调节对运动神经元功能的影响 节律性力变化;和5）确定收缩和 这些肌肉的耐力特性。 要进行的测量 包括肌肉力量、单个运动单位电生理学、肌肉抽搐 特性和诱发电位，以及 有意识的人类受试者的单个运动单位。有很大的临床 对上呼吸道肌肉生理学感兴趣，因为这些 肌肉经常引发或加重阻塞性睡眠呼吸暂停 综合征这种综合征与缺氧和呼吸系统疾病有关。 酸中毒，急性和慢性高血压，并经常导致死亡， 包括婴儿和老人。这些研究将有助于我们 了解上呼吸道肌肉生理学，并将提供 为制定治疗策略奠定基础。

The upper airway muscles of the nose, mouth, tongue and larynx control respiratory airflow resistance, and contract rhythmically in phase with breathing. Despite their significance, information about the physiological properties of upper airway motor units and their role in the gradation of muscle force is unavailable. - The proposed studies are designed to provide fundamental information about the neurophysiology of the nasal dilator muscle motoneurOn pool in healthy human subjects. The nasal dilator muscle was chosen as the experimental model because it is involved in controlling the breath-by-breath diameter of the nasal airway, it is readily accessible in humans, and it responds to reflex-mediated ventilatory stimuli in a manner analogous to the upper airway muscles of the larynx, tongue and face. The Specific Aims include: l) to estimate the number of motor units in the nasal dilator muscles; 2) to determine if the nasal dilator motoneuron pool behaves in accordance with the Size Principle, as occurs in limb muscle; 3) to determine the contributions of rate modulation and motor unit recruitment to the gradation of muscle force; 4) to determine the relationship between the neural drive to the nasal dilator muscles, and the force produced by these muscles during rhythmic, involuntary contractions; and to estimate the relative contributions of motor unit recruitment and rate modulation to the rhythmic force variations; and 5) to determine the contractile and endurance properties of these muscles. The measurements to be made include muscle force, single motor unit electrophysiology, muscle twitch properties and evoked potentials, and spike-triggered average force of single motor units in conscious human subjects. There is great clinical interest in upper airway muscle physiology because malfunction of these muscles often initiates or exacerbates the obstructive sleep apnea syndrome. This syndrome is associated with hypoxia and respiratory acidosis, acute and chronic hypertension, and often results in death in both infants and the elderly. These studies will contribute to our understanding of upper airway muscle physiology, and will provide the foundation for the development of treatment strategies.