Younes Magdy, Loewen Andrea, Ostrowski Michele, Hanly Patrick
Sleep Disorders Centre, Misericordia Health Centre, Winnipeg, Manitoba, Canada ; Sleep Centre, Foothills Medical Centre, University of Calgary, Calgary, Canada.
Sleep Centre, Foothills Medical Centre, University of Calgary, Calgary, Canada.
Sleep. 2014 Nov 1;37(11):1833-49. doi: 10.5665/sleep.4182.
To determine if activation of the genioglossus (GG) muscle during obstructive apnea events involves short-term potentiation (STP) and is followed by sustained activation beyond the obstructive phase (after-discharge).
Physiological study.
Sleep laboratory in a tertiary hospital.
Twenty-one patients with obstructive apnea.
Polysomnography on continuous positive airway pressure (CPAP) with measurement of genioglossus activity. Brief dial-downs of CPAP to induce obstructive events.
Peak, phasic, and tonic genioglossus activities were measured breath-by-breath before, during, and following three-breath obstructions. Tonic but not phasic activity increased immediately following the first obstructed breath (4.9 ± 1.6 versus 3.6 ± 1.2 %GGMAX; P = 0.01) under conditions where stimuli to genioglossus activation were likely constant, strongly implicating STP in mediating recruitment of tonic activity. Both phasic and tonic activities declined slowly after relief of obstruction (after-discharge). Decay time constants were systematically shorter for phasic than for tonic activity (7.5 ± 3.8 versus 18.1 ± 8.4 sec; P < 0.001). Decay time-constant of peak activity correlated with tonic, but not phasic, recruitment. Cortical arousal near the end of obstruction resulted in a lower after-discharge (P < 0.01). Contribution of tonic activity to the increase in peak activity (6-65%Peak), as well as the decay constant (6-30 sec), varied considerably among patients.
Short-term potentiation contributes to recruitment of the genioglossus during obstructive episodes and results in sustained tonic activity beyond the obstructive phase, thereby potentially preventing recurrence of obstruction. Wide response differences among subjects suggest that this mechanism may contribute to severity of the disorder. The after-discharge is inhibited following cortical arousal, potentially explaining arousals' destabilizing effect.
确定阻塞性呼吸暂停事件期间颏舌肌（GG）的激活是否涉及短期增强（STP），以及是否在阻塞期之后持续激活（放电后）。
生理学研究。
三级医院的睡眠实验室。
21名阻塞性呼吸暂停患者。
在持续气道正压通气（CPAP）下进行多导睡眠图检查，并测量颏舌肌活动。短暂降低CPAP以诱发阻塞性事件。
在三次呼吸阻塞之前、期间和之后，逐次呼吸测量颏舌肌的峰值、相位和张力活动。在颏舌肌激活刺激可能恒定的情况下，第一次阻塞性呼吸后立即出现张力性而非相位性活动增加（4.9±1.6对3.6±1.2%GGMAX；P=0.01），强烈提示STP介导张力性活动的募集。阻塞缓解后（放电后），相位和张力性活动均缓慢下降。相位性活动的衰减时间常数系统地短于张力性活动（7.5±3.8对18.1±8.4秒；P<0.001）。峰值活动的衰减时间常数与张力性而非相位性募集相关。阻塞末期附近的皮层觉醒导致较低的放电后活动（P<0.01）。张力性活动对峰值活动增加的贡献（6-65%峰值）以及衰减常数（6-30秒）在患者之间差异很大。
短期增强有助于阻塞发作期间颏舌肌的募集，并导致阻塞期之后持续的张力性活动，从而可能防止阻塞复发。受试者之间广泛的反应差异表明，这种机制可能导致疾病的严重程度。皮层觉醒后放电后活动受到抑制，这可能解释了觉醒的不稳定作用。
