Physiological Mechanisms of Anoxic Tolerance

[04:20017 .杰克逊]这次调查的目的是了解淡水龟这种特殊适应的脊椎动物是如何在长时间缺氧的情况下生存下来的。基于这些知识，长期目标是揭示与这个问题相关的细胞和有机体功能的基本原理。将采用几种实验方法。首先，在整个动物水平上，将使用注射放射性标记化合物来确定关键体液物质、乳酸、二氧化碳和氯离子的分布和排泄。这些化合物在确定缺氧时的酸碱平衡中都很重要，这些实验将阐明这些动物血液pH调节的重要稳态功能。其次，这些动物的心脏功能将被研究，因为这个器官通常对缺氧很敏感。在模拟活体动物缺氧状态的条件下，利用我们测试溶液中已知的血液pH值、离子浓度和儿茶酚胺水平的变化，研究心肌小条的机械特性。第三，骨骼肌对长期缺氧的反应将在完整的动物和分离的肌肉块中使用磁共振波谱技术进行研究。杰克逊博士在这些实验中的目的是评估细胞能量学，做功的能力，以及这种动物在缺氧情况下肌肉活动的恢复能力。像海龟这样的动物专家及其器官系统的显著特征使其成为理解细胞代谢和能量学在缺氧和酸中毒反应中的基本原理的理想准备。更广泛的意义在于理解细胞或器官系统水平上的适应性如何融入到完整动物的整体行为中。＊＊＊

9420017 Jackson The object of this investigation is to understand how a specially adapted vertebrate animal, the freshwater turtle, is able to survive long periods without oxygen. Based on this knowledge, the long-term goal is to uncover fundamental principles of cellular and organismal function related to this problem. Several experimental approaches will be utilized. First, at the whole animal level, the distribution and excretion of key body fluid substances, lactic acid, CO2 and chloride ion will be determined using injected radioactively-labelled compounds. These compounds are all important in determining acid-base balance during anoxia and these experiments will clarify aspects of the important homeostatic function of blood pH regulation in these animals. Second, heart function in these animals will be studied because of the usual sensitivity of this organ to anoxia. Mechanical properties of small strips of cardiac muscle will be studied under conditions that simulate the anoxic state of the living animal, utilizing known changes in blood pH, ion concentrations, and catecholamine levels in our test solutions. Third, the response of skeletal muscle to long-term anoxia will be studied both in the intact animal and in isolated pieces of muscle using the technique of magnetic resonance spectroscopy. Dr. Jackson's object in these experiments is to assess the cellular energetics, the capacity to do work, and the recovery from activity in the muscles of this animal in the absence of oxygen. The remarkable characteristics of an animal specialist such as the turtle and its organ systems make it an ideal preparation for understanding basic principles of cellular metabolism and energetics in response to anoxia and acidosis. Of broader significance is understanding how adaptations revealed at the cell or organ system level incorporate into the integrative behavior of the intact animal. ***