Habib M P, Katz M A
Benjamin W. Zweifach Microcirculation Laboratories, Tucson Veterans Administration Medical Center, Arizona.
J Appl Physiol (1985). 1989 Mar;66(3):1264-7. doi: 10.1152/jappl.1989.66.3.1264.
Ethane quantitated in the expired alveolar gas is a noninvasive measure of free radical activity. This method has been criticized for lack of control of minute ventilation (VE) in spontaneously breathing animals, although ethane, which is poorly soluble in tissues, should not be affected by changes in VE. We measured ethane elimination rates in six strain 13 guinea pigs (GP13) during spontaneous room air breathing and in six room air breathing, pentobarbital-anesthetized, tracheostomized, externally warmed, mechanically ventilated GP13s at various levels of VE. In the ventilated animals, weight0.75/VE (metabolic activity corrected for VE) was a linear function of arterial CO2 tension (PaCO2) drawn from arterial line (r = 0.72, P less than 0.005). However, weight0.75/VE did not correlate with ethane elimination rates (r = 0.12, not significant). The mean (+/- SD) ethane elimination rates in the spontaneously breathing animals was 3.15 +/- 0.96 pmol.min-1.100 g-1 and was not significantly different from the mean rate in the mechanically ventilated animals (3.11 +/- 1.37) over a range of VE's. These data demonstrate that ethane elimination rates are not affected by changes in VE and are unaffected by pentobarbital anesthesia.
呼出肺泡气中乙烷的定量是自由基活性的一种非侵入性测量方法。尽管乙烷在组织中溶解度低，不应受分钟通气量（VE）变化的影响，但该方法因在自主呼吸动物中缺乏对分钟通气量的控制而受到批评。我们测量了6只13号品系豚鼠（GP13）在自主呼吸室内空气时以及6只在室内空气呼吸、戊巴比妥麻醉、气管切开、体外加温、机械通气的GP13在不同VE水平下的乙烷清除率。在通气动物中，体重0.75/VE（经VE校正的代谢活性）是来自动脉导管的动脉二氧化碳分压（PaCO2）的线性函数（r = 0.72，P < 0.005）。然而，体重0.75/VE与乙烷清除率无关（r = 0.12，无显著性）。自主呼吸动物的平均（±标准差）乙烷清除率为3.15±0.96 pmol·min-1·100 g-1，在一系列VE范围内与机械通气动物的平均清除率（3.11±1.37）无显著差异。这些数据表明，乙烷清除率不受VE变化的影响，也不受戊巴比妥麻醉的影响。
