Postural activity of the diaphragm is reduced in humans when respiratory demand increases
Postural activity of the diaphragm is reduced in humans when respiratory demand increases
复制标题
当呼吸需求增加时，人类膈肌的姿势活动会减少
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
S. Gandevia
中科院分区：
文献类型：
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作者：
P. Hodges;Inger Heijnen;S. Gandevia
膈肌和其他呼吸肌的呼吸活动通常与其其他功能相协调，例如肢体运动时躯干的姿势控制。这种整合可以通过呼吸运动神经元的两个输入的总和来实现。本研究探讨了当呼吸驱动随高碳酸血症增加时膈肌的体位活动是否改变。2用肌内电极对13名健康志愿者的横膈膜和其他躯干肌肉进行肌电图（EMG）记录。在控制条件下，当通过增加的死区呼吸时，受试者进行快速重复的手臂运动，以扰乱脊柱的稳定性，每次持续10秒，间隔50秒。试验的前60-120秒，末潮二氧化碳和通气量增加，然后达到平稳期。在死腔呼吸开始时的快速手臂运动中，膈肌肌电图在呼吸和手臂运动频率的叠加调制下变得强直。然而，当高碳酸血症60 s后移动手臂时，呼气时的紧张性膈肌电图和手臂运动时的相活动减少或不存在。类似的变化发生在腹横肌的呼气肌上，但没有发生在竖脊肌上。高碳酸血症60 s后，腹部内压的平均振幅和随手臂运动的相位变化降低。目前的数据表明，中枢呼吸驱动的增强可能减弱到达运动神经元的姿势指令。这种衰减可以影响关键的吸气和呼气肌，并可能在运动神经前部位协调。
1 Respiratory activity of the diaphragm and other respiratory muscles is normally co‐ordinated with their other functions, such as for postural control of the trunk when the limbs move. The integration may occur by summation of two inputs at the respiratory motoneurons. The present study investigated whether postural activity of the diaphragm changed when respiratory drive increased with hypercapnoea. 2 Electromyographic (EMG) recordings of the diaphragm and other trunk muscles were made with intramuscular electrodes in 13 healthy volunteers. Under control conditions and while breathing through increased dead‐space, subjects made rapid repetitive arm movements to disturb the stability of the spine for four periods each lasting 10 s, separated by 50 s. 3 End‐tidal CO2 and ventilation increased for the first 60–120 s of the trial then reached a plateau. During rapid arm movement at the start of dead‐space breathing, diaphragm EMG became tonic with superimposed modulation at the frequencies of respiration and arm movement. However, when the arm was moved after 60 s of hypercapnoea, the tonic diaphragm EMG during expiration and the phasic activity with arm movement were reduced or absent. Similar changes occurred for the expiratory muscle transversus abdominis, but not for the erector spinae. The mean amplitude of intra‐abdominal pressure and the phasic changes with arm movement were reduced after 60 s of hypercapnoea. 4 The present data suggest that increased central respiratory drive may attenuate the postural commands reaching motoneurons. This attenuation can affect the key inspiratory and expiratory muscles and is likely to be co‐ordinated at a pre‐motoneuronal site.