Muza S R, Lee L Y, Pan C P, Zechman F W, Frazier D T
Respir Physiol. 1984 Oct;58(1):77-86. doi: 10.1016/0034-5687(84)90046-x.
In 7 spontaneously breathing dial-urethane anesthetized cats a negative pressure was produced around the thorax and abdomen to increase the functional residual capacity (FRC) by about 1 tidal volume for up to 60 min. A tracheal cannula was connected to a resistive manifold for selective loading of inspiration or expiration. Two resistive loads and tracheal occlusion were presented six times each at control FRC (FRCc), after 60 min at elevated FRC (FRCe) and 30 min after return to FRCc. Inspiratory and expiratory durations (TI and TE) were measured from diaphragmatic EMG. We observed that TI at FRCe (0.88 +/- 0.11 sec) was not significantly shorter than TI at FRCc (1.06 +/- 0.14 sec). Tracheal occlusion at FRCe caused a shorter TI (1.37 +/- 0.15 sec) than at FRCc (1.79 +/- 0.21 sec) (P less than 0.05). The slope (m) of the VI-TI relationship generated by the resistive loads at FRCe was steeper (m = -65 +/- 7 ml X sec-1) and shifted upward from the VI-TI curve at FRCc (-50 +/- 6 ml X sec-1) (P less than 0.05). The VE-TE relationship at FRCe was not significantly changed from control. Thirty minutes following return to FRCc, TI was still slightly shorter (0.96 +/- 0.11 sec) than the initial TI at FRCc. We conclude: (1) The slope of the VI-TI relationship is determined to a great extent by the total lung volume. However, under the conditions of sustained elevation of FRC, this relationship is influenced by the partial adaptation of slowly adapting pulmonary receptors SARs. (2) The increased SAR activity at end expiration during FRCe may not influence the control of TE.
在7只自然呼吸、经二乙氨乙基脲麻醉的猫身上，在其胸部和腹部周围施加负压，使功能残气量（FRC）增加约1个潮气量，持续60分钟。气管插管连接到一个电阻性歧管，用于选择性地加载吸气或呼气阻力。在对照功能残气量（FRCc）时、功能残气量升高60分钟后（FRCe）以及恢复到FRCc 30分钟后，分别对两种阻力负荷和气管阻塞各进行6次测试。通过膈肌肌电图测量吸气和呼气持续时间（TI和TE）。我们观察到，FRCe时的TI（0.88±0.11秒）并不显著短于FRCc时的TI（1.06±0.14秒）。FRCe时气管阻塞导致的TI（1.37±0.15秒）比FRCc时（1.79±0.21秒）短（P<0.05）。FRCe时阻力负荷产生的VI-TI关系的斜率（m）更陡（m = -65±7 ml·sec-1），且相对于FRCc时的VI-TI曲线（-50±6 ml·sec-1）向上偏移（P<0.05）。FRCe时的VE-TE关系与对照相比无显著变化。恢复到FRCc 30分钟后，TI仍略短于FRCc时的初始TI（0.96±0.11秒）。我们得出结论：（1）VI-TI关系的斜率在很大程度上由肺总量决定。然而，在FRC持续升高的情况下，这种关系受到慢适应性肺感受器（SARs）部分适应的影响。（2）FRCe时呼气末SAR活性增加可能不影响TE的控制。
