Daniels C B, Eskandari-Marandi B D, Nicholas T E
Department of Human Physiology, School of Medicine, Flinders University of South Australia, Adelaide.
Respir Physiol. 1993 Oct;94(1):11-23. doi: 10.1016/0034-5687(93)90053-d.
We previously showed that the lung of the central Australian lizard, Ctenophorus nuchalis, contains a large amount of surfactant, the composition of which varies with body temperature. We now show that the specific compliance of the lungs of these lizards remains constant regardless of whether they were maintained at 10, 18, 27, 37 or 43 degrees C for 4 hours. In contrast, the opening pressure was constant up to 27 degrees C, but decreased at 37 and 43 degrees C. When we lavaged the lungs in situ to remove the majority of surfactant, specific compliance decreased while opening pressure increased. The lungs of C. nuchalis are essentially two bubbles, with the left one larger at low and intermediate volumes. After collapsing both lungs, the larger left lung always inflated first. However, following lavage the smaller right lung inflated first. As the larger lung, when collapsed, would have a much greater area of epithelial contact, this result is consistent with surfactant acting as an 'antiglue'. During deflation the smaller lung collapsed first, consistent with the law of Laplace. Compliance did not change in the saline-filled lung suggesting that the gas-liquid interface does not play a major role. We conclude that in the lungs of these lizards, surfactant is acting as an antiglue. This might be important during periods of apnea at low body temperatures, when residual volume is small and epithelial surfaces may come into contact.
我们之前发现，澳大利亚中部蜥蜴——项圈栉尾蜥（Ctenophorus nuchalis）的肺中含有大量表面活性剂，其成分会随体温变化。我们现在发现，无论将这些蜥蜴在10、18、27、37或43摄氏度下维持4小时，它们肺的比顺应性都保持恒定。相比之下，在27摄氏度以下时，开启压力保持恒定，但在37和43摄氏度时降低。当我们原位灌洗肺部以去除大部分表面活性剂时，比顺应性降低而开启压力增加。项圈栉尾蜥的肺本质上是两个气泡，在低容量和中等容量时，左边的气泡更大。使双肺萎陷后，较大的左肺总是先充气。然而，灌洗后较小的右肺先充气。由于较大的肺在萎陷时上皮接触面积会大得多，这一结果与表面活性剂起到“抗黏合剂”的作用相一致。在呼气时，较小的肺先萎陷，这与拉普拉斯定律相符。在充满生理盐水的肺中顺应性没有变化，这表明气液界面不起主要作用。我们得出结论，在这些蜥蜴的肺中，表面活性剂起到抗黏合剂的作用。这在低温下呼吸暂停期间可能很重要，此时残气量小，上皮表面可能会接触。
