Bellemare F, Bigland-Ritchie B, Woods J J
J Appl Physiol (1985). 1986 Sep;61(3):1153-61. doi: 10.1152/jappl.1986.61.3.1153.
The mechanical properties of the human diaphragm have been studied at fractional residual capacity in normal seated subjects with closed glottis. The transdiaphragmatic pressure (Pdi) developed in response to single shocks or to trains of stimuli at increasing frequency was approximately 3 times greater during bilateral than unilateral stimulation. During unilateral phrenic nerve stimulation the Pdi twitches increased as the interval (0-200 ms) of a preceding conditioning stimulus to the contralateral phrenic nerve was decreased suggesting that the two hemidiaphragms are mechanically coupled in series. The contraction time and half-relaxation time of single bilateral twitches as well as the Pdi-frequency relationship (5-35 Hz) during bilateral tetanic stimulation indicate that the contractile properties of the human diaphragm are intermediate between those of fast- and slow-twitch muscle fibers. The results suggest that the contractile properties of the human diaphragm are well illustrated by single bilateral twitches recorded from the relaxed muscle, but that the responses to unilateral stimulation are misleading due to distortion by abnormal changes in the muscle geometry.
在声门闭合的正常坐位受试者中，已对处于残气量分数时的人体膈肌力学特性进行了研究。在双侧刺激期间，对单次电击或频率递增的刺激序列产生的跨膈压（Pdi）大约是单侧刺激时的3倍。在单侧膈神经刺激期间，随着对侧膈神经前一个条件刺激的间隔（0 - 200毫秒）缩短，Pdi抽搐增加，这表明两个半膈肌在力学上串联耦合。单次双侧抽搐的收缩时间和半松弛时间以及双侧强直刺激期间的Pdi - 频率关系（5 - 35赫兹）表明，人体膈肌的收缩特性介于快肌纤维和慢肌纤维之间。结果表明，从松弛肌肉记录的单次双侧抽搐能很好地说明人体膈肌的收缩特性，但由于肌肉几何形状的异常变化导致的扭曲，单侧刺激的反应具有误导性。
