Physiological Mechanisms of Anoxic Tolerance

9728794杰克逊这次调查的目的是了解一种特殊适应的脊椎动物，淡水龟，是如何能够在没有氧气的情况下长时间生存的，以及为什么其他动物不能做到这一点。 长期目标是发现与这种适应相关的细胞和生物体功能的基本原理。 将使用几种实验方法。 首先，将研究海龟的壳和骨骼在使海龟在长期缺氧期间能够承受大量乳酸积累方面的作用。 杰克逊博士发现，壳既释放缓冲化合物到血液中，并作为一个乳酸盐的存储网站。 他将确定骨骼是否也是如此。 壳在乳酸盐储存中的作用是一个新发现，他将在海龟中进一步探索这一点，并将在其他循环乳酸盐大量增加的动物中寻找骨骼或硬组织乳酸盐的摄取。 他推测这可能是许多动物中重要的酸碱调节机制。 此外，龟壳和细胞外液之间的离子交换将研究在粉末壳与不同的pH值和离子组成的溶液孵育的制剂。 还将在完整动物中研究缺氧期间的全身离子交换，以进一步表征壳和体液对酸碱调节的贡献。 他将继续研究海龟心脏对缺氧和酸中毒的适应性，分别使用核磁共振光谱和计算机激活的杠杆系统来研究灌注工作心脏和心室肌条。 这个补助期的一个特别目标是比较耐缺氧的海龟心脏与不耐缺氧的物种（如鳟鱼）的心脏的反应。

9728794 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, and why other animals are unable to do this. The long-term goal is to discover fundamental principles of cellular and organismal function related to this adaptation. Several experimental approaches will be utilized. First, the role of the turtle's shell and skeleton in enabling the turtle to withstand the large buildup of lactic acid during long-term anoxia will be investigated. Dr. Jackson has found that the shell both releases buffer compounds into the blood and serves as a storage site for lactate. He will determine whether the skeleton does the same. The role of the shell in lactate storage is a new finding and he will explore this further in the turtle and will also look for bone or hard tissue lactate uptake in other animals subject to sizable increases in circulating lactate. He postulates that this may be an important acid-base regulatory mechanism in many animals. In addition, the ionic exchanges between the turtle shell and extracellular fluid will be studied in preparations of powdered shell incubated with solutions of different pH and ionic composition. Whole body ionic exchanges during anoxia will also be studied in intact animals to further characterize the contribution of the shell and body fluids to acid-base regulation. He will continue his work on the adaptation of turtle heart to anoxia and acidosis using nuclear magnetic resonance spectroscopy and a computer-activated lever system to study perfused working hearts and ventricular muscle strips, respectively. A particular goal of this grant period is to compare responses in the anoxia-tolerant turtle heart with hearts from anoxia-intolerant species, such as trout.