Gdovin M J, Torgerson C S, Remmers J E
Division of Life Sciences, University of Texas at San Antonio, 78249, USA.
Respir Physiol. 1998 Aug;113(2):135-46. doi: 10.1016/s0034-5687(98)00061-9.
A decerebrate, spontaneously breathing tadpole preparation (Taylor-Kollros stages 16-19) was used to test the general hypothesis that the efferent bursting activities of cranial nerves (CN) V, VII and spinal nerve (SN) II are respiratory in nature, and, in particular, to identify separate and specific neural correlates of gill and lung ventilation. Oropharyngeal pressure (POP), intrapulmonary pressure (PIP), electromyogram (EMG) of the buccal levator muscle (interhyoideus), and efferent neural activities of CN V, CN VII and SN II were recorded while the animal was exposed to hyperoxia (100% inspired O2), normoxia (21% inspired O2), and hypoxia (10, 5 and 0% inspired O2). Gill ventilation, indicated by fluctuations in POP at constant PIP, was characterized by high-frequency, low-amplitude bursts of action potentials in CN V and VII and interhyoideus EMG without phasic activity in SN II. Lung breaths, indicated by oscillations in POP and PIP were characterized by large bursts in EMG, CN V and VII together with a large burst in SN II. The amplitude of the moving average of nerve activities associated with lung ventilation was significantly larger than those associated with gill ventilation. During gill ventilation, the burst in CN V led that in CN VII, and both preceded the rise in POP. By contrast, a more synchronous neural burst onset pattern was observed during lung ventilation. The results document the neural, muscular, and mechanical characteristics of gill and lung ventilation in the tadpole, and establish bursting activity in SN II as a specific marker for lung ventilation in the metamorphic tadpole.
采用去大脑、自主呼吸的蝌蚪标本（泰勒 - 科尔罗斯16 - 19期）来检验一般假设，即脑神经（CN）V、VII和脊神经（SN）II的传出爆发活动本质上是呼吸性的，特别是要确定鳃和肺通气各自独立且特定的神经关联。在动物暴露于高氧（吸入100% O₂）、常氧（吸入21% O₂）和低氧（吸入10%、5%和0% O₂）的情况下，记录口咽压力（POP）、肺内压力（PIP）、颊提肌（舌骨间肌）的肌电图（EMG）以及CN V、CN VII和SN II的传出神经活动。在恒定PIP下，由POP波动表示的鳃通气的特征是CN V和VII以及舌骨间肌EMG中高频、低幅度的动作电位爆发，而SN II无相位活动。由POP和PIP振荡表示的肺呼吸的特征是EMG、CN V和VII中的大爆发以及SN II中的大爆发。与肺通气相关的神经活动的移动平均值的幅度明显大于与鳃通气相关的幅度。在鳃通气期间，CN V中的爆发先于CN VII中的爆发，且两者都先于POP的升高。相比之下，在肺通气期间观察到更同步的神经爆发起始模式。这些结果记录了蝌蚪鳃和肺通气的神经、肌肉和机械特征，并将SN II中的爆发活动确立为变态蝌蚪肺通气的特定标志物。
