Ward M E, Deschamps A, Roussos C, Hussain S N
Division of Pulmonary Medicine, Royal Victoria Hospital, Montreal, Quebec, Canada.
J Appl Physiol (1985). 1992 Aug;73(2):563-70. doi: 10.1152/jappl.1992.73.2.563.
Ventilation and electromyogram (EMG) activities of the right hemidiaphragm, parasternal intercostal, triangularis sterni, transversus abdominis, genioglossus, and alae nasi muscles were measured before and during central stimulation of the left thoracic phrenic nerve in 10 alpha-chloralose anesthetized vagotomized dogs. Pressure in the carotid sinuses was fixed to maintain baroreflex activity constant. The nerve was stimulated for 1 min with a frequency of 40 Hz and stimulus duration of 1 ms at voltages of 5, 10, 20, and 30 times twitch threshold (TT). At five times TT, no change in ventilation or EMG activity occurred. At 10 times TT, neither tidal volume nor breathing frequency increased sufficiently to reach statistical significance, although the change in their product (minute ventilation) was significant (P less than 0.05). At 20 and 30 times TT, increases in both breathing frequency and tidal volume were significant. At these stimulus intensities, the increases in ventilation were accompanied by approximately equal increases in the activity of the diaphragm, parasternal, and alae nasi muscles. The increase in genioglossus activity was much greater than that of the other inspiratory muscles. Phrenic nerve stimulation also elicited inhomogeneous activation of the expiratory muscles. The transversus abdominis activity increased significantly at intensities from 10 to 30 times TT, whereas the activity of the triangularis sterni remained unchanged. The high stimulation intensities required suggest that the activation of afferent fiber groups III and IV is involved in the response. We conclude that thin-fiber phrenic afferent activation exerts a nonuniform effect on the upper airway, rib cage, and abdominal muscles and may play a role in the control of respiratory muscle recruitment.
在10只α-氯醛糖麻醉并切断迷走神经的犬中，测量了左胸段膈神经中枢刺激前后右半侧膈肌、胸骨旁肋间肌、胸骨三角肌、腹横肌、颏舌肌和鼻翼肌的通气及肌电图（EMG）活动。固定颈动脉窦压力以维持压力反射活动恒定。以40Hz的频率、1ms的刺激持续时间，在5、10、20和30倍阈下刺激（TT）电压下，对神经进行1分钟的刺激。在5倍TT时，通气或EMG活动无变化。在10倍TT时，潮气量和呼吸频率均未充分增加至具有统计学意义，尽管它们的乘积（分钟通气量）变化具有统计学意义（P<0.05）。在20和30倍TT时，呼吸频率和潮气量均显著增加。在这些刺激强度下，通气增加伴随着膈肌、胸骨旁肌和鼻翼肌活动的近似等量增加。颏舌肌活动的增加远大于其他吸气肌。膈神经刺激还引起呼气肌的不均匀激活。腹横肌活动在10至30倍TT强度下显著增加，而胸骨三角肌活动保持不变。所需的高刺激强度表明传入纤维III和IV组的激活参与了该反应。我们得出结论，细纤维膈神经传入激活对上气道、胸廓和腹部肌肉产生不均匀影响，可能在呼吸肌募集控制中发挥作用。
