家兔膈神经呼气相电活动的观察

在52只麻醉兔和4只清醒兔上均观察到,自然呼吸时膈神经于呼气相有紧张性放电。同时引导膈肌肌电表明这种活动与膈肌紧张性的维持有关。这种电活动在切断引导电极外周段的膈神经后仍然存在。通气量不足、动脉血 PCO_2增加或 PO_2减少使其减少或消失;吸入纯氧或过度通气引起相反效应。切断窦神经或延髓腹外侧面化学敏感区局部贴敷浸有普鲁卡因的滤纸片,使膈神经呼气相放电增强;颈动脉窦区注入30—75μg NaCN 或将 pH=6的酸性人工脑脊液滤纸片贴于延髓化学敏感区,使膈神经呼气相放电减弱。本工作提示正常血气浓度及其变化经相同的外周和中枢化学感受机制同时发动两种调节过程:1.通过调节吸气肌位相性活动而调节肺通气量;2.通过调节吸气肌呼气相紧张性活动而调节肺机能余气量。

OBSERVATIONS ON PHRENIC DISCHARGES DURING EXPIRATORY PHASEIN THE RABBIT

In 52 anesthetized and 4 conscious eupnic rabbits,tonic phrenic dischargesdturing expiratory phase were observed.The discharges persisted after paralyzingskeletal muscles,cutting phrenic nerves or during considerable variations in arterialblood pressure.They decreased during hypercapnia,hypoxia or hypoventilation.They were also depressed when carotid chemoreceptors were stimulated by locallyadministered NaCN,or when a minute piece of filter paper soaked in artificial CSFof pH 6 was placed bilaterally on the ventrolateral medullary chemosensitive area.The opposite effects were induced by hyperventilation,pure O_2 inhalation,bilateralsinus denervation or procain-soaked filter paper placed on the central chemosensi-tive area.Synchronous recording of diaphragmatic disharges showed that the ex-piratory discharges of the phrenic nerve were responsible for the maintenance ofthe diaphragmatic tone.It is suggested that normal concentrations of blood gases and their variations(?)nitiate two regulatory processes through identical peripheral and central chemore-ceptive mechanisms:The regulation of pulmonary ventilation mediated by phasicactivity of the inspiratory muscle and the regulation of FRC mediated by tonic activ-ity of the same muscle during the expiratory phase.