PHRENIC MOTO-NEURONS IN THE CAT - SUB-POPULATIONS AND NATURE OF RESPIRATORY DRIVE POTENTIALS
PHRENIC MOTO-NEURONS IN THE CAT - SUB-POPULATIONS AND NATURE OF RESPIRATORY DRIVE POTENTIALS
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DOI：
10.1152/jn.1979.42.1.76
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发表时间：
1979-01-01
影响因子：
2.5
通讯作者：
BERGER, AJ
中科院分区：
文献类型：
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作者：
BERGER, AJ
1.对麻醉、人工呼吸、轻度高碳酸血症猫的78个膈运动神经元(PM)进行了细胞内记录。2.根据膜电位在呼气(E)期间的轨迹，确定了三个PM亚群(A、B和A/B型)。A型细胞呈现完全线性的运动轨迹。在59个A型细胞中，有51个细胞在E期开始时迅速超极化，随后出现缓慢的超极化增强。B型(13个细胞)和A/B(6个细胞)在E型细胞中具有非线性轨迹。3.对轴突传导速度、呼气相输入阻力、初始除极速率和吸气时起始峰电位的测量表明，B型细胞轴突传导速度明显慢于A型细胞，输入电阻高于A型细胞，初始除极速率大于A型细胞，起始峰起始时间早于A型细胞。A/B型细胞的性质介于其他细胞类型之间。这些结果支持了PM池不均匀的假设。4.通过桥接电路将增加的超极化波转变为超极化电流注入的去极化波，直接证明了对所有类型PM的活性E相抑制。因此，电刺激时PM的超极化不仅仅是由于中枢去易化所致。5.在超极化电流注入过程中，所有质膜的吸气相膜电位轨迹与A类细胞对照时的去极化轨迹相似。这些结果支持这样的结论，即PM池中的所有细胞在吸入时都接受了类似的中枢兴奋性突触输入。B型的快速初始去极化及其伴随的早期尖峰起始是其呼气相抑制的反弹兴奋的部分结果，以及较高的输入阻力，可能是由于细胞较小。6.在膈运动核内记录到呼气相关神经活动。根据其活动的时间模式，提示这些呼气相关神经元可能与主动抑制PM有关。
1. Intracellular recordings were made from 78 phrenic motoneurons (PM) in anesthetized, paralyzed, artificially ventilated cats that were slightly hypercapnic. 2. Three subpopulations of PM (types A, B, and A/B) were identified on the basis of their membrane potential trajectories during expiration (E). Type A cells exhibited wholly linear trajectories. These were rapidly hyperpolarized at the onset of E followed by a slow ramp of increasing hyperpolarization observed in 51 of 59 type A cells. Types B (13 cells) and A/B (6 cells) had nonlinear trajectories in E. Type B cells approached their end-expiratory potential levels more slowly. 3. Measurements of axonal conduction velocity, expiratory phase input resistance, initial depolarization rate, and initial spike onset during inspiration revealed that type B cells had significantly slower axonal conduction velocities, higher input resistances, greater initial depolarization rates, and earlier initial spike onsets than type A cells. The properties of type A/B were intermediate between the other cell types. These results support the hypothesis that the PM pool is not homogeneous. 4. Active E-phase inhibition of all types of PM was directly demonstrated by reversal of the increasing hyperpolarizing wave to a depolarizing wave with hyperpolarizing current injection using a bridge circuit. Thus hyperpolarization of PM during E is not merely due to a central disfacilitation. 5. During hyperpolarizing current injection the inspiratory phase membrane potential trajectory of all PM became a ramp depolarization similar to that seen during control conditions in type A cells. These results support the conclusion that all cells within the PM pool are receiving a similar central excitatory synaptic input during inspiration. The rapid initial depolarization of type B and their concomitant early spike onset is a consequence in part of a rebound excitation from their expiratory phase inhibition as well as a higher input resistance, probably due to a smaller cell size. 6. Expiratory related neural activity was recorded within the phrenic motor nucleus. It is suggested that these expiratory related neural elements, based on the temporal pattern of their activity, may be responsible for the active inhibition of PM.