Haxhiu M A, Mitra J, van Lunteren E, Prabhakar N R, Cherniack N S
Am J Physiol. 1985 Aug;249(2 Pt 2):R266-73. doi: 10.1152/ajpregu.1985.249.2.R266.
Respiratory activity can be substantially affected by perturbations confined to the superficial areas of the ventrolateral surface of the medulla, the putative site of central chemoreceptors. In this study we compared the effect of thermal and pharmacological interventions that are known to alter respiration on the electrical activity of the rib cage muscles, diaphragm, and abdominal muscles. With cooling of the intermediate areas to 20 degrees C, tidal volume decreased 50%. The electrical activity of the diaphragm decreased less than the other muscles (diaphragm less than inspiratory intercostal less than expiratory intercostal). Abdominal muscle activity was depressed as much as expiratory intercostal activity but reappeared with further cooling to 10 degrees C if cooling was prolonged and the vagi were intact. gamma-Aminobutyric acid (GABA) and its agonist muscimol, like cooling, reduced expiratory and inspiratory intercostal activity more than diaphragm activity. Nicotine, a respiratory stimulant, applied to the intermediate areas increased inspiratory intercostal activity more than the diaphragm. The results suggest that under the conditions of the experiments the rib cage musculature, and probably the abdominal muscles as well, are more responsive than the diaphragm to depression or excitation of chemosensitive elements in the superficial regions of the medulla.
呼吸活动会受到局限于延髓腹外侧表面浅层区域（假定的中枢化学感受器所在部位）的干扰的显著影响。在本研究中，我们比较了已知会改变呼吸的热干预和药物干预对胸廓肌肉、膈肌和腹部肌肉电活动的影响。将中间区域冷却至20摄氏度时，潮气量减少了50%。膈肌的电活动比其他肌肉减少得少（膈肌＜吸气肋间肌＜呼气肋间肌）。腹部肌肉活动与呼气肋间肌活动一样受到抑制，但如果冷却时间延长且迷走神经完整，进一步冷却至10摄氏度时腹部肌肉活动会再次出现。γ-氨基丁酸（GABA）及其激动剂蝇蕈醇与冷却一样，对呼气和吸气肋间肌活动的抑制作用比对膈肌活动的抑制作用更大。呼吸兴奋剂尼古丁作用于中间区域时，对吸气肋间肌活动的增强作用比对膈肌的增强作用更大。结果表明，在实验条件下，胸廓肌肉组织以及可能还有腹部肌肉，比膈肌对延髓浅层区域化学敏感元件的抑制或兴奋更敏感。
