Shea S A, Akahoshi T, Edwards J K, White D P
Harvard Medical School, and Circadian, Neuroendocrine, and Sleep Disorders Section, Brigham and Women's Hospital, Boston, Massachusetts, USA.
Am J Respir Crit Care Med. 2000 Aug;162(2 Pt 1):559-65. doi: 10.1164/ajrccm.162.2.9908111.
Genioglossal muscle (GG) activity is modulated by both chemoreceptive and mechanoreceptive reflexes that help stabilize airway patency. We assessed the effects of blood gas changes, within the range encountered during mild obstructive apnea-arousal cycles, on GG activity and the GG reflex to upper airway negative pressure. Eighteen healthy adults were studied while awake under 5 conditions: (1) baseline (PET(CO(2)) = 40 mm Hg, Sa(O(2)) = 99%); (2) hypercapnia (PET(CO(2)) = 45 mm Hg); (3) hypocapnia (PET(CO(2)) = 35 mm Hg, induced via hyperventilation with an iron lung ventilator); (4) hypoxia (Sa(O(2)) = 87%); and (5) hypercapnia plus hypoxia (PET(CO(2)) = 45 mm Hg, Sa(O(2)) = 87%). Measurements included airflow, choanal and epiglottic pressures (Pchoa and Pepi), upper airway resistance, phasic and tonic GG EMG, and the GG reflex to negative pressure (Pchoa = -12.5 cm H(2)O). Ventilation increased from a baseline of 10.7 up to 22.7 L. min(-1) under conditions of altered blood gases. Peak inspiratory phasic GG EMG increased from 6. 5 to 11.1% of maximal contraction but there were no significant changes in either tonic GG EMG (range, 4.3 to 5.8% of maximum) or magnitude of the GG reflex (range, 4.1 to 5.5% of maximum). Among conditions there was a high correlation between upper airway pressures and peak phasic GG EMG (Pchoa, r = 0.97, p < 0.01; Pepi, r = 0.87; p = 0.06). We conclude that in this range of blood gases: (1) the GG reflex to negative pressure is unchanged; (2) slow airway pressure changes throughout inspiration, generated either actively or passively, influence GG EMG activity; and (3) mechanoreceptive control of GG EMG can fully explain all changes in GG activity, suggesting that chemoreceptive inputs to GG are minimal, or are not simply summated with mechanoreceptor inputs.
颏舌肌（GG）的活动受化学感受性和机械感受性反射调节，这些反射有助于稳定气道通畅。我们评估了在轻度阻塞性呼吸暂停-觉醒周期中出现的血气变化范围内，其对GG活动以及GG对上气道负压的反射的影响。对18名健康成年人在清醒状态下的5种情况进行了研究：（1）基线状态（呼气末二氧化碳分压[PET(CO₂)] = 40 mmHg，动脉血氧饱和度[Sa(O₂)] = 99%）；（2）高碳酸血症（PET(CO₂) = 45 mmHg）；（3）低碳酸血症（PET(CO₂) = 35 mmHg，通过铁肺通气机过度通气诱导）；（4）低氧血症（Sa(O₂) = 87%）；以及（5）高碳酸血症加低氧血症（PET(CO₂) = 45 mmHg，Sa(O₂) = 87%）。测量指标包括气流、后鼻孔和会厌压力（Pchoa和Pepi）、上气道阻力、颏舌肌肌电图的相位和张力成分，以及颏舌肌对负压的反射（Pchoa = -12.5 cm H₂O）。在血气改变的情况下，通气量从基线的10.7升·分钟⁻¹增加到22.7升·分钟⁻¹。吸气峰值相位颏舌肌肌电图从最大收缩的6.5%增加到11.1%，但颏舌肌张力性肌电图（范围为最大值的4.3%至5.8%）或颏舌肌反射幅度（范围为最大值的4.1%至5.5%）均无显著变化。在不同情况之间，上气道压力与峰值相位颏舌肌肌电图之间存在高度相关性（Pchoa，r = 0.97，p < 0.01；Pepi，r = 0.87；p = 0.06）。我们得出结论，在这个血气范围内：（1）颏舌肌对负压的反射未改变；（2）整个吸气过程中主动或被动产生的缓慢气道压力变化会影响颏舌肌肌电图活动；（3）颏舌肌肌电图的机械感受性控制可以完全解释颏舌肌活动的所有变化，这表明对颏舌肌的化学感受性输入极少，或者并非简单地与机械感受器输入相加。
