De Troyer André, Leduc Dimitri
Laboratory of Cardiorespiratory Physiology, Brussels School of Medicine, Brussels, Belgium.
J Appl Physiol (1985). 2006 Jul;101(1):169-75. doi: 10.1152/japplphysiol.01465.2005.
The inspiratory intercostal muscles enhance the force generated by the diaphragm during lung expansion. However, whether the diaphragm also alters the force developed by the inspiratory intercostals is unknown. Two experiments were performed in dogs to answer the question. In the first experiment, external, cranially oriented forces were applied to the different rib pairs to assess the effect of diaphragmatic contraction on the coupling between the ribs and the lung. The fall in airway opening pressure (deltaPa(O)) produced by a given force on the ribs was invariably greater during phrenic nerve stimulation than with the diaphragm relaxed. The cranial rib displacement (Xr), however, was 40-50% smaller, thus indicating that the increase in deltaPa(O) was exclusively the result of the increase in diaphragmatic elastance. In the second experiment, the parasternal intercostal muscle in the fourth interspace was selectively activated, and the effects of diaphragmatic contraction on the deltaPa(O) and Xr caused by parasternal activation were compared with those observed during the application of external loads on the ribs. Stimulating the phrenic nerves increased the deltaPa(O) and reduced the Xr produced by the parasternal intercostal, and the magnitudes of the changes were identical to those observed during external rib loading. It is concluded, therefore, that the diaphragm has no significant synergistic or antagonistic effect on the force developed by the parasternal intercostals during breathing. This lack of effect is probably related to the constraint imposed on intercostal muscle length by the ribs and sternum.
吸气时肋间肌可增强膈肌在肺扩张过程中产生的力量。然而，膈肌是否也会改变吸气肋间肌产生的力量尚不清楚。为此在犬身上进行了两项实验来回答这个问题。在第一个实验中，对不同肋骨对施加向外、颅侧方向的力，以评估膈肌收缩对肋骨与肺之间耦合的影响。在膈神经刺激期间，肋骨上给定力产生的气道开口压力下降（ΔPa(O)）总是比膈肌松弛时更大。然而，颅侧肋骨位移（Xr）却小40 - 50%，这表明ΔPa(O)的增加完全是膈肌弹性增加的结果。在第二个实验中，选择性激活第四肋间间隙的胸骨旁肋间肌，并将膈肌收缩对胸骨旁激活引起的ΔPa(O)和Xr的影响与在肋骨上施加外部负荷时观察到的影响进行比较。刺激膈神经会增加ΔPa(O)并减少胸骨旁肋间肌产生的Xr，变化幅度与肋骨外部加载时观察到的相同。因此得出结论，在呼吸过程中，膈肌对胸骨旁肋间肌产生的力量没有显著的协同或拮抗作用。这种无影响可能与肋骨和胸骨对肋间肌长度的限制有关。
