Tantucci C, Mehiri S, Duguet A, Similowski T, Arnulf I, Zelter M, Derenne J P, Milic-Emili J
Clinica di Semeiotica Medica, University of Ancona, 60020 Ancona, Italy.
J Appl Physiol (1985). 1998 Mar;84(3):1076-82. doi: 10.1152/jappl.1998.84.3.1076.
The application of negative expiratory pressure (NEP) at end expiration has been shown to cause reflex-mediated activation of the genioglossus muscle in awake humans. To test whether a reflex contraction of pharyngeal dilator muscles also occurs in response to NEP applied in early expiration, the effect on genioglossus muscle reflex activity of NEP pulses of 500 ms, given 0.2 s after the onset of expiration and during the end-expiratory pause, was assessed in 10 normal awake subjects at rest. The raw and integrated surface electromyogram of the genioglossus (EMGgg) was recorded with airflow and mouth pressure under control conditions and with NEP ranging from -3 to -10 cmH2O. Intraoral EMGgg was also recorded under the same experimental conditions in two subjects. The application of NEP at the end-expiratory pause elicited a consistent reflex response of EMGgg in seven subjects with a mean latency of 68 +/- 5 ms. In contrast, when NEP was applied at the onset of expiration, EMGgg reflex activity was invariably observed in only one subject. No relationship was found between steady increase or abrupt fall in expiratory flow and the presence or the absence of a reflex activity of genioglossus during sudden application of NEP at the beginning of expiration. Our results show that a reflex activity of genioglossus is elicited much more commonly during application of NEP at the end rather than at the onset of expiration. These findings also suggest that when NEP is applied in early expiration to detect intrathoracic flow limitation the absence of upper airways narrowing does not imply the occurrence of a reflex-mediated activation of genioglossus and vice versa.
呼气末施加呼气负压（NEP）已被证明可引起清醒人类颏舌肌的反射性激活。为了测试在呼气早期施加NEP时是否也会发生咽扩张肌的反射性收缩，我们在10名静息状态下的正常清醒受试者中评估了在呼气开始后0.2秒和呼气末暂停期间给予500毫秒NEP脉冲对颏舌肌反射活动的影响。在对照条件下以及NEP范围为-3至-10 cmH₂O时，记录颏舌肌的原始和积分表面肌电图（EMGgg），同时记录气流和口腔压力。还在两名受试者的相同实验条件下记录了口腔内的EMGgg。在呼气末暂停时施加NEP在7名受试者中引起了EMGgg一致的反射反应，平均潜伏期为68±5毫秒。相比之下，当在呼气开始时施加NEP时，仅在一名受试者中始终观察到EMGgg反射活动。在呼气开始时突然施加NEP期间，呼气流量的稳定增加或突然下降与颏舌肌反射活动的存在与否之间未发现相关性。我们的结果表明，在呼气末而非呼气开始时施加NEP期间，颏舌肌的反射活动更常见。这些发现还表明，当在呼气早期应用NEP来检测胸内血流受限情况时，上气道无狭窄并不意味着会发生反射介导的颏舌肌激活，反之亦然。
