Regulatory Control of the Upper Airway Muscle Genioglossus During Sleep

睡眠时呼吸困难是一个主要的健康问题。阻塞性睡眠呼吸暂停(OSA)是这些疾病中最常见的，在大约4%的男性和2%的女性中发现。在阻塞性睡眠呼吸暂停综合征患者中，上呼吸道(UA)在睡眠时会塌陷，从而阻止气流，导致血液中的氧气水平下降。呼吸道塌陷是因为在睡眠期间，UA的肌肉无法抵消通过吸气作用在呼吸道内产生的负压。如果负压过大，导致呼吸道塌陷，患者必须醒来才能重新打开呼吸道。随着UA在恢复睡眠时再次崩溃，这个循环变得重复，导致睡眠中断。阻塞性睡眠呼吸暂停综合症是一种重大的健康风险，会导致心脏病、死亡率增加、白天嗜睡、白天表现下降和事故风险增加。阻塞性睡眠呼吸暂停是由两个相互作用的因素造成的。首先，呼吸道狭窄的人在吸气时必须产生更大的负压。第二，也是关键的一点，睡眠会减少UA肌肉的活动。观察到阻塞性睡眠呼吸暂停综合征患者在清醒时不会阻碍睡眠，这一睡眠效应的重要性由此可见一斑。因此，睡眠期间的呼吸异常是这种疾病的必要组成部分。然而，在了解UA肌肉的运动控制方面进展缓慢。我们认为，这在一定程度上是因为研究集中在分析UA肌肉的活动，而不是测量组成肌肉的单个运动单位。在这个项目中，我们建议研究UA肌，膝舌肌(GG)中与睡眠相关的运动单位的活动。GG在UA中起着关键作用，因为它防止舌头向后折叠进入呼吸道。我们期望这一方法将为舌头运动控制和GG在阻塞性睡眠呼吸暂停综合征的发展中所起的作用提供见解。

Difficulty breathing during sleep is a major health problem. Obstructive Sleep Apnoea (OSA) is the most frequently occurring of these disorders, being found in approximately 4% of males and 2% of females. In OSA the upper airway (UA) collapses during sleep preventing airflow and causing a fall in oxygen levels in the blood. The airway collapses because during sleep muscles in the UA are unable to offset the negative pressure generated within the airway by the effort of inspiring. If the negative pressure is too great and the airway collapses the person has to wake up to reopen the airway. As the UA collapses again on the return of sleep, the cycle becomes repetitive, causing sleep disruption. OSA is a significant health risk causing heart disorders, increased mortality, daytime sleepiness, reduced daytime performance and increased risk of accidents. OSA is due to two interacting factors. First, people with a narrow airway have to generate a greater negative pressure during inspiration. Second, and critically, sleep reduces activity in the UA muscles. The importance of this sleep effect is indicated by the observation that OSA patients do not obstruct while awake. Thus, a respiratory abnormality during sleep is a necessary component of the disorder. However, progress in understanding motor control of UA muscles has been slow. We argue that this is in part because research has concentrated on analysing the activity of the UA muscles, rather than measuring the individual motor units that make up the muscles. In this project we propose to investigate the sleep related activity of individual motor units in the UA muscle, genioglossus (GG). GG plays a critical role in the UA as it keeps the tongue from collapsing backwards into the airway. We anticipate that this approach will provide insights into motor control of the tongue and the role of GG in the development of OSA.