Crossley Dane A, Hicks James W
Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA.
Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2024 Dec;298:111736. doi: 10.1016/j.cbpa.2024.111736. Epub 2024 Sep 5.
The embryonic chicken is a valuable model for studying the maturation of cardiovascular physiology and the responses of this organ system to environmental manipulations such as acute hypoxia. Hypoxia determines not only the general cardiovascular response but also is a tool to determine the system's maturation of reflexive control. Several studies suggest embryonic chicken's regulation of the cardiovascular response to hypoxia, but no studies have measured the blood chemistry changes that accompany these responses. To clarify the changes in blood parameters accompanying cardiovascular function changes during acute hypoxia, we designed a study to investigate the blood chemistry (pO, pCO, pH, lactate, glucose, and blood ions) in developing embryos during acute hypoxia (O = 10 %). Embryos ranging from day 13 to 21 of incubation were sampled during a control period and at the end of a 5-min of hypoxia. Hypoxia caused bradycardia on all days of incubation. The maximal blood hypoxic response occurred on day 15, with lactate increasing 7-fold (2.5 to 16.6 mmol/l) while glucose levels decreased by 50 % (136 to 63 mg/dl). Furthermore, hypoxia reduced pH (7.40 to 7.26), which peaked on day 15. These data indicate that a 5-min exposure to 10 % O is sufficient to induce dramatic changes in blood chemistry however chorioallantoic arterial blood pO was unchanged on most days of the study. Therefore, given the cardiovascular response to hypoxia and the increase in blood lactate prior to airbreathing in the chicken embryo, the embryonic tissues experienced an acute stress that may be the basis for the change in cardiovascular function during the exposure.
胚胎期的鸡是研究心血管生理成熟以及该器官系统对急性缺氧等环境操纵反应的宝贵模型。缺氧不仅决定了一般的心血管反应，还是确定该系统反射控制成熟度的一种手段。多项研究表明胚胎期的鸡对缺氧的心血管反应具有调节作用，但尚无研究测量伴随这些反应的血液化学变化。为了阐明急性缺氧期间伴随心血管功能变化的血液参数变化，我们设计了一项研究，以调查急性缺氧（氧气含量为10%）期间发育中胚胎的血液化学指标（氧分压、二氧化碳分压、pH值、乳酸、葡萄糖和血液离子）。在对照期以及5分钟缺氧结束时，对孵化13至21天的胚胎进行采样。缺氧在孵化的所有天数均导致心动过缓。最大的血液缺氧反应出现在第15天，乳酸增加了7倍（从2.5毫摩尔/升增至16.6毫摩尔/升），而葡萄糖水平下降了50%（从136毫克/分升降至63毫克/分升）。此外，缺氧使pH值降低（从7.40降至7.26），在第15天达到峰值。这些数据表明，暴露于10%的氧气环境5分钟足以引起血液化学的显著变化，然而在研究的大多数天数里，尿囊动脉血氧分压并未改变。因此，鉴于鸡胚胎对缺氧的心血管反应以及在开始呼吸空气之前血液乳酸的增加，胚胎组织经历了急性应激，这可能是暴露期间心血管功能变化的基础。
