Interaction of fatigue and hypercapnia in the canine diaphragm.
Interaction of fatigue and hypercapnia in the canine diaphragm.
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犬膈肌疲劳和高碳酸血症的相互作用。
DOI：
10.1152/jappl.1988.64.4.1636
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
Roussos,C
中科院分区：
文献类型：
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作者：
Schnader,J;Howell,S;Fitzgerald,RS;Roussos,C
我们研究了10只开胸犬，并在1、20、50和80 Hz的频率刺激下，测量了方案的每个阶段横膈膜压力（Pdi）。动脉PCO2 (PaCO2)≤26,36 - 50,89 Torr。膈肌重复刺激（30hz）使膈肌疲劳。在疲劳活动期间，5只动物出现高碳酸血症，另外5只出现低碳酸血症。在协议的每个周期生成频率- pdi曲线。数据表明：1)高碳酸血症时疲劳至初始Pdi值的50%明显快于低碳酸血症时；2)疲劳前和疲劳后的平均Pdi值在频率、疲劳和PaCO2的所有相互作用下均不受疲劳环境（高碳酸血症与低碳酸血症）的影响；3)四种频率下高碳酸血症对Pdi的降低百分比相同；4)低碳酸血症没有改变疲劳前后的频率- pdi曲线；5)半松弛时间，不受PaCO2影响，疲劳延长。我们得出结论，高碳酸血症膈肌比低碳酸血症膈肌的耐力更低，尽管疲劳和高碳酸血症都会降低Pdi，但它们似乎是通过不同机制起作用的独立实体。
We studied 10 open-chest dogs and measured the pressure across the diaphragm (Pdi) in each period of the protocol during stimulation at frequencies of 1, 20, 50, and 80 Hz. Three ranges of arterial PCO2 (PaCO2) were examined: less than or equal to 26, 36-50, and greater than or equal to 89 Torr. The diaphragm was fatigued with repetitive phrenic stimulation (30 Hz). During the fatiguing activity, five of the animals were subjected to hypercapnia and the other five to hypocapnia. A frequency-Pdi curve was generated for each period in the protocol. The data show that 1) fatiguing to 50% of the initial Pdi value during hypercapnia was significantly more rapid than during hypocapnia; 2) both the prefatigue and postfatigue mean Pdi values over all interactions of frequency, fatigue, and PaCO2 were unaffected by the fatiguing environment (hypercapnia vs. hypocapnia); 3) the percent reduction of Pdi by hypercapnia was the same at all four frequencies; 4) hypocapnia did not alter either the pre- or postfatigue frequency-Pdi curve; and 5) one-half relaxation time, unaffected by PaCO2, was prolonged by fatigue. We conclude that the hypercapnic diaphragm has less endurance than the hypocapnic diaphragm and that although both fatigue and hypercapnia decrease Pdi, they appear to be separate entities working through different mechanisms.