上呼吸道氣流與二氧化碳濃度增加對膈神經活動的影響

Interactive Effects of Airflow in the Upper Airway and Carbon Dioxide on Phrenic Discharge

黃基礎(Ji-Chuu Hwang) ； 鄭劍庭(Chiang-Ting Cheng) ； 廖娟妙(Jiuan-Miun Liao)

《師大生物學報》 23期 (1988/10) Pp. 189-202

摘要

本研究的主要目的是探討膈神經在不同二氧化碳濃度下對上呼吸道氣流變化的反應。採用麻醉猫，切斷迷走神經，麻痺並以人工呼吸器維持其生命，製作一個獨立上呼吸道。猫呼氣末氣體濃度維持在高氧而二氧化碳正常。三種不同吸氣氣流是每公斤體重每分鐘1、2及3公升。氣流為2和3 1/min/kg時，膈神經活動無論是CO_2正常或中度增加皆受氣流抑制，但CO_2增加為F_(ETCO_2)=0.09時，2 1/min/kg的氣流就不再抑制膈神經放電。在CO_2正常時，氣流抑制的劑量反應曲線廻歸直線為91.7-6.5 X_1，當CO_2增加到F_(ETCO_2) = 0.09時，反應曲線向上移動，其廻歸直線為97.1-5.9 X_1。這些結果暗示上呼吸道傳來的刺激與化學感受器所測得之化學變化可能在中樞發生相互作用，然後影響膈神經的活動。

並列摘要

The purpose of the present report was to evaluate phrenic response to airflow changes in the upper airway (UAW) at different levels of end-tidal concentration of carbon dioxide (F_(ETCO_2)). An isolated UAW was produced in pentobarbital-anesthetized, vagotomized, paralyzed and ventilated cats. Phrenic activities were monitored at normocapnia and hypercapnia in hyperoxia. Three levels of inspiratory airflow were used; 1, 2 and 3 1/min/kg. Significant decreases in phrenic activity with airflow of 2 and 3 1/min/kg passing through the UAW were observed at normocapnia and mild hypercapnia. At high level of carbon dioxide (F_(ETCO_2) = 0.09), decrease of phrenic burst in response to airflow of 2 1/min/kg became undetectable. Intercept and slop of the dose-response curve of phrenic discharges with airflow at F_(ETCO_2) of 0. 04 was 91.7 and-6.5 respectively, and became 97.1 and - 5.9 at 0.09. Thus, the dose-response curve of phrenic activities with different airflow rate passing through the UAW was shifted to the right or upward as end-tidal concentration of CO_2 was increased. These results indicate that an interaction between signals from the UAW and the chemoreceptor may occur in the central nervous system.