Kuwana S, Natsui T
Jpn J Physiol. 1985;35(5):803-15. doi: 10.2170/jjphysiol.35.803.
The effect of the elimination of input via the carotid chemoreceptor on respiratory output was examined quantitatively in anesthetized, vagotomized, and paralyzed cats. The integrated phrenic nerve activity (PNA) was recorded as an indication of output of the respiratory center. Also, the elimination of the carotid chemoreflex drive was repeatedly done by a cold block of the carotid sinus nerve at various PCO2 levels during hyperoxia, normoxia, and hypoxia. The blockade induced a reduction in PNA at each PCO2 level in every PO2 group. If the highest PNA value recorded at a high PCO2 in each PO2 condition was assigned a value of 100%, the reduction of the PNA by the blockade, i.e., the respiratory effect of the carotid chemoreflex drive, would be slightly larger during normoxia (16%) than during hyperoxia (8.7%), but would be independent of PCO2. During hypoxia, this chemoreflex effect was about 40% of a low PCO2, and decreased with increments of PCO2, finally reaching about 20% of a high PCO2 level. Furthermore, the relative contribution of the carotid chemoreceptor to respiratory output, expressed as the ratio of the PNA reduction during blockade to the PNA before blockade, was inversely proportional to both PO2 and PCO2. It is concluded that the interaction of the peripheral and central chemoreceptor drive is hypoadditive at moderate and high PCO2 levels in anesthetized cats, and this interaction is emphasized by central hypoxia.
在麻醉、切断迷走神经并使其麻痹的猫身上，定量研究了通过颈动脉化学感受器消除输入对呼吸输出的影响。记录膈神经活动积分（PNA）作为呼吸中枢输出的指标。此外，在高氧、常氧和低氧期间，通过在不同的PCO2水平下对颈动脉窦神经进行冷阻滞，反复消除颈动脉化学反射驱动。在每个PO2组中，这种阻滞在每个PCO2水平均导致PNA降低。如果将每种PO2条件下在高PCO2时记录到的最高PNA值设定为100%，则阻滞引起的PNA降低，即颈动脉化学反射驱动的呼吸效应，在常氧时（16%）略大于高氧时（8.7%），但与PCO2无关。在低氧期间，这种化学反射效应在低PCO2时约为40%，并随PCO2的升高而降低，最终在高PCO2水平时达到约20%。此外，颈动脉化学感受器对呼吸输出的相对贡献，以阻滞期间PNA降低与阻滞前PNA的比值表示，与PO2和PCO2均呈反比。得出的结论是，在麻醉猫中，外周和中枢化学感受器驱动在中等和高PCO2水平时的相互作用是低相加性的，并且中枢低氧会增强这种相互作用。
