Grunstein M M, Wyszogrodski I, Milic-Emili J
J Appl Physiol. 1975 May;38(5):869-74. doi: 10.1152/jappl.1975.38.5.869.
In six spontaneously breathing anesthetized cats, intermittently subjected to inspiratory elastic loads, we have studied the relationships between tidal volume (VT) and the durations of inspiration (Ti) and breath duration (Ttot) obtained during spontaneous ventilation from resting lung volume (FRCc) and from elevated end-expiratory levels. The latter was elevated by submerging the expiratory breathing line into a column of water, representing the addition of an expiratory threshold load (ETL). The VT vs. Ti relationships obtained at different end-expiratory levels were similar, indicating that during ETL the vagal mechanism regulating Ti responds only to lung volume changes above the new end-expiratory level and is independent of the absolute end-expiratory lung volume. Single vagal fiber recordings suggest that this effect on Ti control may be explained on the basis of adaptation occurring at the level of the pulmonary stretch receptors. The control of Ttot, on the other hand, was found to depend both on the Ti of the preceding breath (phasic component) and on a separate vagal mechanism specifically affecting the duration of expiration (Te) in response to changes in the absolute end-expiratory lung volume. The latter mechanism is functionally inoperative at FRCc.
在六只自主呼吸的麻醉猫中，间歇性施加吸气弹性负荷，我们研究了潮气量（VT）与在自主通气过程中从静息肺容积（FRCc）和呼气末升高水平获得的吸气持续时间（Ti）和呼吸持续时间（Ttot）之间的关系。后者通过将呼气呼吸管路浸入一列水中来升高，这代表增加了呼气阈值负荷（ETL）。在不同呼气末水平获得的VT与Ti关系相似，表明在ETL期间，调节Ti的迷走神经机制仅对高于新呼气末水平的肺容积变化做出反应，且与绝对呼气末肺容积无关。单个迷走神经纤维记录表明，对Ti控制的这种影响可能基于肺牵张感受器水平发生的适应来解释。另一方面，发现Ttot的控制既取决于前一次呼吸的Ti（相位成分），也取决于一种独立的迷走神经机制，该机制专门响应绝对呼气末肺容积的变化来影响呼气持续时间（Te）。后一种机制在FRCc时不起作用。
