Stable isotopic and metabolomic studies in a model of lactic acidosis tolerance

描述（由申请人提供）：拟议研究的目标是利用深度缺氧和酸中毒的彩龟来更好地了解脊椎动物无氧代谢的基本过程，这与大量人类代谢性疾病密切相关，特别是那些涉及氧气运输受损的疾病。利用哺乳动物模型进行的脊椎动物无氧代谢和随后的有氧恢复的传统研究受到哺乳动物对缺氧和乳酸酸中毒的低耐受性以及高代谢率导致的快速代谢物周转率的限制，特别是在啮齿动物中。彩龟是已知的最耐缺氧的空气呼吸脊椎动物物种，其代谢率比类似大小的哺乳动物低一个数量级，并且可以积累乳酸浓度超过哺乳动物致死极限的4-5倍。为了更好地了解恢复过程中无氧代谢和代谢物通量的机制，我们的长期目标是：1)表征缺氧期间和之后的血浆和组织代谢组学特征，2)研究缺氧期间和缺氧后代谢组中乳酸的代谢命运，3)确定哪些底物可以促进正常和恢复代谢。温度诱导的代谢率变化在所有这些过程中的相互作用也将被研究。这项工作首次将代谢应激研究的理想模式生物与稳定同位素和代谢组学方法结合起来，代表了一种创新的无氧代谢研究方法。我们期望对脊椎动物的代谢率和乳酸动力学之间的关系有更深入的了解，并对这些临床重要的代谢过程有新的和一般的见解。

DESCRIPTION (provided by applicant): The goal of the proposed research is to use the profoundly anoxia and acidosis-resistant painted turtle to better understand the basic processes underlying vertebrate anaerobic metabolism, which is closely associated with a large number of human metabolic diseases, particularly those involving impaired oxygen transport. Insights from conventional studies utilizing mammalian models of vertebrate anaerobic metabolism and subsequent aerobic recovery are limited by mammals' low tolerance to anoxia and lactic acidosis and the rapid metabolite turnover rates resulting from high metabolic rates, particularly in rodents. The painted turtle is the most anoxia-tolerant air-breathing vertebrate species known, has metabolic rates an order of magnitude lower than a similar sized mammal, and can accumulate lactic acid to concentrations 4-5x greater than the lethal limit for mammals. With the long-term goal of better understanding the mechanisms underlying anaerobic metabolism and metabolite fluxes during recovery, our aims are to: 1) Characterize the plasma and tissue metabolomic profiles during and following anoxia, 2) Investigate the metabolic fates of lactate within the metabolome during and after anoxia, and 3) Determine what substrates fuel normal and recovery metabolism. The interaction of temperature-induced changes in metabolic rate on all of these processes will also be investigated. This work represents an innovative approach to studies of anaerobic metabolism by combining, for the first time, an ideal model organism for studies of metabolic stress with stable isotopic and metabolomics approaches. We expect to gain a deeper understanding of the relationship between metabolic rate and lactate kinetics in vertebrates and to gain new and general insights into these clinically important metabolic processes. PUBLIC HEALTH RELEVANCE: This study will provide new insights into the mechanisms underlying anaerobic metabolism and lactic acid clearance in vertebrates. Ultimately, this will contribute to our broader understanding of the causes and consequences of many metabolic diseases in humans, particularly those involving metabolic acidosis and those related to limitations in oxygen transport.