Fregosi R F, Lansing R W
Department of Physiology, University of Arizona, Tucson 85721-0093, USA.
J Appl Physiol (1985). 1995 Oct;79(4):1330-7. doi: 10.1152/jappl.1995.79.4.1330.
Our aim was to test the following hypotheses: 1) neural drive to the muscles of the alae nasi (AN) is proportional to nasal airflow and is independent of the overall level of central respiratory drive, and 2) the switch from nasal to oronasal breathing corresponds to the onset of marked flow turbulence in the nasal airway. Total and nasal inspired ventilation rates (VI) and the electromyogram (EMG) of the AN muscles were measured in seven subjects during progressive-intensity bicycling exercise. In separate experiments in six subjects the nasal VI corresponding to the transition from laminar to turbulent airflow was determined by measuring the pressure-flow relationship of the nasal airway with anterior rhinomanometry. Nasal VI accounted for 70 +/- 11% of total VI at rest and 27 +/- 8% (SE) at 90% of the maximal attainable power (max). Nasal VI and integrated AN EMG activities increased linearly with exercise intensity up to 60% of the max power, but both variables plateaued at this level even though total VI (and central respiratory drive) began to increase exponentially as exercise intensity increased to 90% max. The onset of the exponential rise in total VI was associated with a sharp increase in oral VI and with the onset of marked flow turbulence in the nasal airway. The results suggest that during incremental exercise 1) changes in AN EMG activities are highly correlated with changes in nasal VI, 2) turbulent flow in the nose may be the stimulus for the switch to oronasal breathing so that total pulmonary resistance is minimized, and 3) the correlation between nasal airflow and neural drive to the AN muscles is probably mediated by mechanisms that monitor airway resistance. Although these mechanisms were not identified, the most likely possibilities are receptors in the upper and/or lower airways that are sensitive to negative transmural pressure, or to effort sensations leading to greater corollary motor discharge to nasal dilator muscle motoneurons.
1）鼻翼（AN）肌肉的神经驱动与鼻气流成正比，且独立于中枢呼吸驱动的总体水平；2）从鼻呼吸转换为口鼻呼吸与鼻气道中明显的气流紊乱的开始相对应。在七名受试者进行递增强度的自行车运动期间，测量了总吸气通气率和鼻吸气通气率（VI）以及AN肌肉的肌电图（EMG）。在另外针对六名受试者的实验中，通过用前鼻测压法测量鼻气道的压力-流量关系，确定了与从层流到湍流气流转变相对应的鼻VI。静息时鼻VI占总VI的70±11%，在最大可达到功率（max）的90%时为27±8%（标准误）。鼻VI和整合的AN EMG活动随运动强度线性增加，直至达到最大功率的60%，但即使总VI（和中枢呼吸驱动）随着运动强度增加到最大功率的90%开始呈指数增加，这两个变量在此水平也趋于平稳。总VI的指数上升开始与口腔VI的急剧增加以及鼻气道中明显的气流紊乱的开始相关。结果表明，在递增运动期间：1）AN EMG活动的变化与鼻VI的变化高度相关；2）鼻腔中的湍流可能是转换为口鼻呼吸的刺激因素，从而使总肺阻力最小化；3）鼻气流与AN肌肉神经驱动之间的相关性可能由监测气道阻力的机制介导。尽管这些机制尚未确定，但最有可能的情况是上呼吸道和/或下呼吸道中对负跨壁压或导致向鼻扩张肌运动神经元产生更大伴随运动放电的用力感觉敏感的受体。
