Pérez Fontán J J, Ray A O
Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06510.
J Appl Physiol (1985). 1991 Apr;70(4):1617-26. doi: 10.1152/jappl.1991.70.4.1617.
To study the postnatal maturation of vagal control of airway muscle tone, we determined the effects of vagotomy and supramaximal vagal stimulation on the resistance of the respiratory system in eight newborn and seven 6-wk-old piglets. Because the lung periphery has distinctive responses to cholinergic agonists and a lower density of vagal fibers and cholinergic receptors than the central airways, we partitioned the respiratory resistance of the piglets between central airways (Rc) and peripheral airways and lung tissue (Rp) with bronchial catheters inserted in a retrograde manner. The piglets were anesthetized with alpha-chloralose and ventilated with positive airway pressure. Vagotomy did not change Rc or Rp in either the newborn or the 6-wk-old piglets. Vagal stimulation, on the other hand, increased both Rc (median increase 53% in the newborn and 72% in the 6-wk-old piglets) and Rp (54 and 42%, respectively). At all states of vagal tone, Rp increased as the lungs were inflated, suggesting a large contribution of tissue viscoelasticity to this resistance. Our results demonstrate that vagal bronchomotor tone is absent during mechanical ventilation with positive pressure in the developing piglet. However, vagal innervation of both central airways and tissue contractile elements is functionally competent at the time of birth in this species.
为研究迷走神经对气道肌张力的产后成熟情况，我们测定了迷走神经切断术和迷走神经超强刺激对8只新生仔猪和7只6周龄仔猪呼吸系统阻力的影响。由于肺外周对胆碱能激动剂有独特反应，且迷走神经纤维和胆碱能受体密度低于中央气道，我们通过逆行插入支气管导管将仔猪的呼吸阻力分为中央气道阻力（Rc）和外周气道及肺组织阻力（Rp）。仔猪用α-氯醛糖麻醉，并采用气道正压通气。迷走神经切断术在新生仔猪和6周龄仔猪中均未改变Rc或Rp。另一方面，迷走神经刺激增加了Rc（新生仔猪中值增加53%，6周龄仔猪中值增加72%）和Rp（分别为54%和42%）。在迷走神经张力的所有状态下，随着肺膨胀Rp增加，表明组织粘弹性对该阻力有很大贡献。我们的结果表明，在发育中的仔猪进行气道正压机械通气时，迷走神经支气管运动张力不存在。然而，在该物种出生时，中央气道和组织收缩元件的迷走神经支配在功能上是有效的。
