三种自然刺激对家兔颈动脉体化学感受器活动的影响

EFFECTS OF DIFFERENT NATURAL STIMULANTS ON THE ACTIVITY OF THE RABBITS′ CAROTID CHEMORECEPTOR

在游离灌流的颈动脉体窦神经标本，观察了ＰＯ２降低、ＰＣＯ２增加和ｐＨ降低对化学感受性单位放电的影响。共记录了３２个有自发放电的化学感受性单位对三种自然刺激的反应。所得结果如下：（１）只对ＰＯ２降低有反应的化学感受性单位（对ＰＣＯ２增加及ｐＨ降低均无反应）有１０例（占总数的３１％），对三种自然刺激均有反应的化学感受性单位有９例（占２８％），对ＰＯ２降低和ＰＣＯ２增加有反应的化学感受性单位有９例（占２８％），对ＰＯ２降低和ｐＨ降低两种刺激有反应的化学感受性单位有３例（占９％），另有一例只对ｐＨ降低有反应。（２）不同的自然刺激对化学感受性单位放电频率影响不一致。ＰＯ２降低使放电频率增加最多，其次是ＰＣＯ２增加，作用最弱的是ｐＨ降低。根据以上结果，似可认为，在颈动脉体中存在着不同生理特性的化学感受性单位，它们对ＰＯ２，ＰＣＯ２或ｐＨ有不同的敏感性。

The effects of different natural stimulants on the afferent unit discharge of rabbitcarotid chemoreceptors were studied in the in vitro carotid body- sinus nerve preparation. A total of 32 chemoreceptive units were recorded. The results were as follows:(1) of the 32 units, 10 (31 % ) showed chemosensory responses only to PO2 decrease;9 (28 % ) to all stimulants (PO2 decrease, PCO2 increase and PH decrease); 9 (28% )to PO2 decrease and PCO2 increase; 3 (9 % ) to PO2 decrease and PH decrease; only oneto pH decrease. (2) The potency of the three natural stimulants in eliciting the changesin intensity of discharge showed a decreasing order as follows: PO2 decrease > PCO2increase > pH decrease. The above results suggest that the carotid body may containonly one or a combination of 2 or 3 kinds of chemoreceptors respectively sensitive to decrease PO2 to increase PCO2 or decrease pH.