Mechanisms of Anoxic Tolerance and Metabolic Depression

杰克逊博士和他的同事们计划对爬行动物和哺乳动物的酸碱、离子和代谢调节机制进行研究。爬行动物的研究源于过去对淡水龟异常耐缺氧的观察。我们将朝三个方向努力。首先，最近观察到的甲鱼缺氧和/或酸中毒时血浆儿茶酚胺(肾上腺素和去甲肾上腺素)的增加将被进一步记录下来，并将调查其功能意义和对该动物缺氧耐受性的可能贡献。其次，在低氧期间，龟的血浆钙浓度显著增加，这使我们对该物种钙动力学和钙代谢的激素调节进行了广泛的研究。他计划将这只海龟的反应与另一种缺乏海龟富含矿物质的壳的爬行动物进行比较。第三，由于他最近的研究结果未能揭示血液酸中毒与缺氧耐受性或厌氧代谢之间的相关性，他将研究在各种类型的缺氧和酸化条件下选定组织的细胞内pH和代谢物控制。这个项目中提出的假设，即细胞酸中毒抑制能量代谢，与最终提出的关于异温蝙蝠Eptesicus fuscus的项目有关。初步数据表明，该物种在20摄氏度的昏迷期间采取了双重的pH控制策略：夏季恒定pH，冬季恒定pH。主要研究人员的目标是在血液和细胞中证实这一观察结果，并评估其与迟钝蝙蝠能量保护的相关性。总体而言，我们的目标是了解调节低代谢状态的机制。

Dr. Jackson and his associates plan studies on mechanisms of acid-base, ionic, and metabolic regulation in reptiles and mammals. The reptile studies derive from past observations on the extraordinary anoxic tolerance of the freshwater turtle, Chrysemys picta bellii. Three directions will be pursued. First, the increase in plasma catecholamines (epinephrine and norepinephrine), that have been recenty observed when turtles are anoxic and/or acidotic, will be further documented and its functional significance and possible contribution to this animal's anoxic tolerance will be investigated. Second, the marked increase in plasma calcium concentration in turtles during anoxia leads us to a broad study of calcium kinetics and hormonal regulation of calcium metabolism in this species. He plans to compare the responses of the turtle to another reptile that lacks the turtle's mineral-rich shell. Third, because his recent results have failed to reveal a correlation between blood acidosis and anoxic tolerance or anaerobic metabolism he will investigate intracellular pH and metabolite control of selected tissues during various types of anoxic and acidotic conditions. The hypothesis presented in this project, that cellular acidosis depresses energy metabolism, relates to the final proposed project on the heterothermic bat, Eptesicus fuscus. Preliminary data suggest a dual pH control strategy in this species during torpor at 20 degrees centigrade: alphastat in the summer, pH- stat in the winter. The principal investigator's objective is to verify this observation in both blood and cells and evaluate its relevance to energy conservation of torpid bats. Overall, the goal is an understanding of the mechanisms regulating hypometabolic states.