Eldridge F L, Chen Z
Department of Medicine, University of North Carolina, Chapel Hill 27599.
Respir Physiol. 1992 Oct;90(1):31-46. doi: 10.1016/0034-5687(92)90132-g.
We recorded phrenic nerve activities and single unit firings of mesencephalic neurons in 19 decerebrate, paralyzed and ventilated cats, in which the spinal cord had been transected at C7-T1 and carotid sinus nerves cut but vagus nerves left intact. After we had found neurons with respiratory-associated rhythmic activity, we tested the effect of changing pulmonary vagal input by (1) stopping and restarting the ventilator; (2) changing the ventilator's tidal volume; (3) progressively cooling the vagus nerves to 6-7 degrees C; and (4) vagal section. All methods of testing yielded results that showed that vagal input, probably from pulmonary stretch receptors, tonically inhibits the respiratory-associated firing of the mesencephalic neurons by a direct mechanism that is independent of a vagal effect on medullary respiratory drive. We have suggested that these neurons are involved in the mechanism that conveys information about respiration to the cortex where it may be interpreted as the sensation of dyspnea. If so, movement and increased expansion of the lungs can be expected to lessen the sensation.
我们记录了19只去大脑、瘫痪且通气的猫的膈神经活动和中脑神经元的单单位放电情况。这些猫的脊髓在C7 - T1水平横断，颈动脉窦神经切断，但迷走神经保持完整。在找到具有呼吸相关节律活动的神经元后，我们通过以下方式测试改变肺迷走神经输入的效果：（1）停止并重新启动呼吸机；（2）改变呼吸机的潮气量；（3）将迷走神经逐渐冷却至6 - 7摄氏度；（4）切断迷走神经。所有测试方法得到的结果均表明，迷走神经输入，可能来自肺牵张感受器，通过一种独立于迷走神经对延髓呼吸驱动作用的直接机制，对中脑神经元的呼吸相关放电产生紧张性抑制。我们曾提出，这些神经元参与了将呼吸信息传递至皮层的机制，在皮层中该信息可能被解读为呼吸困难的感觉。如果是这样，那么可以预期肺部的运动和扩张增加会减轻这种感觉。
