Vinegar A, Sinnett E E, Leith D E
J Appl Physiol Respir Environ Exerc Physiol. 1979 May;46(5):867-71. doi: 10.1152/jappl.1979.46.5.867.
Awake mice (22.6--32.6 g) were anesthetized intravenously during head-out body plethysmography. One minute after pentobarbital sodium anesthesia, tidal volume had fallen from 0.28 +/- 0.04 to 0.14 +/- 0.02 ml and frequency from 181 +/- 20 to 142 +/- 8. Functional residual capacity (FRC) decreased by 0.10 +/- 0.02 ml. Expiratory flow-volume curves were linear, highly repeatable, and submaximal over substantial portions of expiration in awake and anesthetized mice; and expiration was interrupted at substantial flows that abruptly fell to and crossed zero as inspiration interrupted relaxed expiration. FRC is maintained at a higher level in awake mice due to a higher tidal volume and frequency coupled with expiratory braking (persistent inspiratory muscle activity or increased glottal resistance). In anesthetized mice, the absence of braking, coupled with reductions in tidal volume and frequency and a prolonged expiratory period, leads to FRCs that approach relaxation volume (Vr). An equation in derived to express the difference between FRC and Vr in terms of the portion of tidal volume expired without braking, the slope of the linear portion of the expiratory flow-volume curve expressed as V/V, the time fraction of one respiratory cycle spent in unbraked expiration, and respiratory frequency.
在清醒小鼠（体重22.6 - 32.6克）进行头出式体容积描记法时，通过静脉注射使其麻醉。戊巴比妥钠麻醉一分钟后，潮气量从0.28±0.04毫升降至0.14±0.02毫升，频率从181±20次/分钟降至142±8次/分钟。功能残气量（FRC）减少了0.10±0.02毫升。清醒和麻醉小鼠在呼气的大部分时间里，呼气流速 - 容积曲线呈线性、高度可重复且未达最大值；呼气在较大流速时中断，随着吸气打断松弛的呼气，流速会突然降至并越过零。由于潮气量和频率较高，再加上呼气制动（持续的吸气肌活动或声门阻力增加），清醒小鼠的FRC维持在较高水平。在麻醉小鼠中，缺乏制动，再加上潮气量和频率降低以及呼气期延长，导致FRC接近松弛容积（Vr）。推导出一个方程，用无制动时呼出的潮气量部分、以V/V表示的呼气流速 - 容积曲线线性部分的斜率、无制动呼气在一个呼吸周期中所占的时间分数以及呼吸频率来表示FRC与Vr之间的差异。
