Lambert C R, Gladden L B, Nichols W W, Pepine C J
J Appl Physiol (1985). 1985 Apr;58(4):1128-35. doi: 10.1152/jappl.1985.58.4.1128.
Femoral arterial pressure-flow relations and vascular impedance were studied during isometric contraction of the gastrocnemius-plantaris muscle group in anesthetized dogs. Contractions were synchronized with the electrocardiogram to occur in the first or second half of the cardiac cycle and included twitches as well as low-, intermediate-, and high-frequency tetanuses. The effects of fatigue and recovery were also documented. Marked changes in pressure and flow waveforms and corresponding femoral arterial input impedance spectra were seen for all contraction modes. Impedance moduli and estimated characteristic impedance were elevated regardless of contraction mode and were associated with fluctuations in impedance phase. All tetanuses placed in the first half of the cardiac cycle produced a striking and consistent reversal of impedance phase for the fundamental harmonic from negative to positive values which decreased with progressive fatigue. During recovery, impedance spectra were unchanged from control spectra. We have demonstrated marked alterations in pressure and flow waveforms and impedance spectral patterns during isometric contraction in the canine hindlimb. These changes may be explained by 1) markedly increased wave reflection as a result of muscle contraction and/or 2) the generation of a retrograde pulse by contracting muscle that fuses with the antegrade pulse of cardiac origin.
在麻醉犬的腓肠肌 - 跖肌肌群等长收缩期间，研究了股动脉压力 - 血流关系和血管阻抗。收缩与心电图同步，发生在心动周期的前半段或后半段，包括单收缩以及低、中、高频强直收缩。还记录了疲劳和恢复的影响。对于所有收缩模式，压力和血流波形以及相应的股动脉输入阻抗谱都有明显变化。无论收缩模式如何，阻抗模量和估计的特性阻抗均升高，并且与阻抗相位的波动有关。所有置于心动周期前半段的强直收缩都会使基波的阻抗相位从负值显著且一致地反转到正值，且随着疲劳进展而减小。在恢复期间，阻抗谱与对照谱无变化。我们已经证明，在犬后肢等长收缩期间，压力和血流波形以及阻抗谱模式有明显改变。这些变化可能由以下原因解释：1）由于肌肉收缩导致波反射显著增加；和/或2）收缩肌肉产生与心脏起源的顺行脉冲融合的逆行脉冲。
