Neural respiratory and circulatory interaction during chemoreceptor stimulation and cooling of ventral medulla in cats.
Neural respiratory and circulatory interaction during chemoreceptor stimulation and cooling of ventral medulla in cats.
复制标题
猫化学感受器刺激和腹侧髓质冷却过程中的神经呼吸和循环相互作用。
DOI：
10.1113/jphysiol.1986.sp015931
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
Millhorn,DE
中科院分区：
文献类型：
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作者：
Millhorn,DE
呼吸和交感神经活动的影响，测量为综合膈神经和颈神经活动分别，在改变从中央化学感受器的输入进行了研究，麻醉，麻痹猫的颈动脉窦神经和迷走神经已被切断。通过对位于延髓腹侧表面附近的中间区域进行分级冷阻断或通过潮气末PCO2的逐步增加来改变中枢呼吸驱动。颈神经活动表现出紧张（或平均）水平的活动和一个突出的周期性放电，是在与膈神经活动的阶段。当潮气末PCO2保持恒定时，将中间区域分级局灶性冷却至20 ℃，导致膈神经活动、吸气相关放电幅度和平均动脉压进行性降低，但平均颈神经活动仅小幅降低。在没有吸气相关放电的情况下（即当膈神经活动低于呼吸暂停阈值时）冷却中间区域导致动脉压下降幅度小得多。潮气末PCO2的逐步增加导致颈神经和膈神经活动的进行性增加。颈部活动的增加主要是由于（如果不是全部的话）吸气相关放电幅度的逐渐增加。这些发现表明，在刺激中枢化学感受器和中间区的分级冷阻滞期间，对交感神经活动的主要影响是吸气相关放电幅度的变化，并表明伴随中枢化学感受器刺激和中间区的分级冷阻滞的动脉压变化是由吸气相关放电介导的，而不是由平均动脉压的增加介导的。交感神经活动水平。当通过冷却中间区域将膈神经活动降低至呼吸暂停阈值以下时，潮气末PCO2的逐步增加引起颈神经活动的抑制而不是刺激。这一发现表明，交感神经元不是由中央化学感受器输入直接激活，而是通过颅内连接与呼吸调节相关的神经元网络间接激活。
The effects on respiratory and sympathetic neural activity, measured as integrated phrenic and cervical nerve activities respectively, during changing input from the central chemoreceptors was studied in anaesthetized, paralysed cats whose carotid sinus nerves and vagus nerves had been cut. Central respiratory drive was altered either by graded cold block of the intermediate areas, located bilaterally near the ventral surface of the medulla oblongata, or by step increases in end‐tidal PCO2. Cervical nerve activity showed both a tonic (or mean) level of activity and a prominent cyclic discharge that was in phase with phrenic nerve activity. Graded focal cooling of the intermediate areas to 20 degrees C when end‐tidal PCO2 was kept constant caused progressive decreases in phrenic activity, the amplitude of the inspiratory related discharge and mean arterial pressure, but only a small decrease in mean cervical nerve activity. Cooling the intermediate areas in the absence of the inspiratory related discharge (i.e. when phrenic activity was below the apnoeic threshold) led to a much smaller decrease in arterial pressure. Step increases of end‐tidal PCO2 caused progressive increases of both cervical and phrenic nerve activities. The increase in cervical activity was due primarily, if not wholly, to a progressive increase in the amplitude of the inspiratory related discharge. These findings show that the predominant effect on sympathetic activity during stimulation of the central chemoreceptor and graded cold block of the intermediate areas is a change in the amplitude of the inspiratory related discharge and suggest that the change in arterial pressure that accompanies central chemoreceptor stimulation and graded cold block of the intermediate areas is mediated by the inspiratory related discharge rather than by an increase in the mean level of sympathetic activity. When phrenic activity was lowered to below apnoeic threshold by cooling the intermediate areas, step increases in end‐tidal PCO2 caused inhibition rather than stimulation of cervical nerve activity. This finding indicates that sympathetic neurones are not activated by central chemoreceptor input directly, but rather indirectly via intracranial connexions with neuronal networks involved in regulation of respiration.