St John W M, Bartlett D
J Appl Physiol Respir Environ Exerc Physiol. 1981 May;50(5):994-8. doi: 10.1152/jappl.1981.50.5.994.
Single-fiber phrenic nerve action potentials were recorded together with activity of contralateral whole phrenic nerve rootlets during eupnea and gasping in decerebrate, cerebellectomized, vagotomized, paralyzed, and ventilated cats. Gasping was reversibly produced by cooling a fork thermode positioned through the pontomedullary junction. In eupnea, phrenic motoneurons were distributed into "early" and "late" populations relative to their onset of activity during inspiration. During gasping, however, both fiber types typically commenced activity at the beginning of the phrenic nerve burst. Moreover, late fibers, but not early units, exhibited an augmentation of discharge frequency with the onset of gasping. The concentration of activity of all phrenic motoneurons at the beginning of inspiration and the increase in late-unit discharge frequency account for the faster rise of the gasp as compared with the eupneic breath. It is concluded that the pattern of phrenic nerve activation during gasping differs fundamentally from that during eupnea. These results support the concept that mechanisms underlying the neurogenesis of gasping and eupnea may not be identical.
在对去大脑、小脑切除、迷走神经切断、麻痹并通气的猫进行平静呼吸和喘息期间，记录了单纤维膈神经动作电位以及对侧整个膈神经根丝的活动。通过冷却置于脑桥延髓交界处的叉形温度电极可逆地诱发喘息。在平静呼吸时，膈运动神经元根据其在吸气期间开始活动的时间分为“早期”和“晚期”群体。然而，在喘息期间，两种纤维类型通常在膈神经爆发开始时就开始活动。此外，晚期纤维而非早期单位，随着喘息的开始，放电频率增加。与平静呼吸相比，所有膈运动神经元在吸气开始时的活动集中以及晚期单位放电频率的增加导致了喘息上升更快。得出的结论是，喘息期间膈神经激活模式与平静呼吸期间的模式根本不同。这些结果支持了喘息和平静呼吸神经发生的潜在机制可能不同的概念。
