Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, São Paulo, Brazil.
Programa de Pós-graduação em Biologia Comparada, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, São Paulo, Brazil.
J Exp Biol. 2024 Mar 15;227(6). doi: 10.1242/jeb.247241. Epub 2024 Mar 25.
Teiid lizards possess an incomplete post-hepatic septum (PHS) separating the lungs and liver from the remaining viscera, and within this group, Salvator merianae has the most complete PHS. In this study, we explored the combined effects of the presence of the PHS and alterations in abdominal volume on the mechanics of the respiratory system. The PHS is believed to act as a mechanical barrier, mitigating the impact of the viscera on the lungs. Using established protocols, we determined static (Cstat) and dynamic (Cdyn) compliance, lung volume and work of breathing for the respiratory system in tegu lizards with intact (PHS+) or removed (PHS-) PHS, combined with (balloon+) or without (balloon-) increased abdominal volume. The removal of the PHS significantly reduced resting lung volume and Cdyn, as well as significantly increasing the work of breathing. An increase in abdominal volume significantly reduced Cstat, Cdyn, and resting and maximum lung volume. However, the work of breathing increased less in the PHS+/balloon+ treatment than in the PHS- treatments. These results highlight the barrier function of the PHS within the tegu lizard's body cavity. The septum effectively reduces the impact of the viscera on the respiratory system, enabling the lungs to be ventilated at a low work level, even when abdominal volume is increased. The presence of the PHS in teiid lizards underscores how extrapulmonary structures, such as septal divisions of the body cavity, can profoundly affect pulmonary breathing mechanics.
鬣蜥具有不完整的肝后隔（PHS），将肺和肝脏与其余内脏隔开，而在这群鬣蜥中，萨尔瓦多巨蜥拥有最完整的 PHS。在这项研究中，我们探讨了 PHS 的存在和腹部容积变化对呼吸系统力学的综合影响。PHS 被认为是一种机械屏障，可以减轻内脏对肺部的影响。我们使用既定的方案，确定了完整 PHS（PHS+）或去除 PHS（PHS-）的鬣蜥呼吸系统的静态（Cstat）和动态（Cdyn）顺应性、肺容积和呼吸功，同时结合（气囊+）或不结合（气囊-）增加的腹部容积。去除 PHS 显著降低了静息肺容积和 Cdyn，并显著增加了呼吸功。增加腹部容积显著降低了 Cstat、Cdyn、静息和最大肺容积。然而，与 PHS-处理相比，PHS+/气囊+处理中的呼吸功增加较少。这些结果强调了 PHS 在鬣蜥体腔内的屏障功能。隔有效地降低了内脏对呼吸系统的影响，使肺部能够在低工作水平下进行通气，即使腹部容积增加。鬣蜥中 PHS 的存在突出表明，诸如体腔的隔部分离等肺外结构如何深刻地影响肺呼吸力学。
