METABOLIC ADAPTATIONS OF NEONATES TO EXTRAUTERINE LIFE

其目的是了解细胞和生化事件， 导致出生后早期成功代谢适应。 我们有 表明围产期胰岛素/胰高血糖素和组织pO 2调节的变化 从肝细胞质中突然净摄取腺嘌呤核苷酸（ADN） 进入线粒体，导致基质大量增加， ATP+ADP+AMP池大小在出生后几小时内。 线粒体ADN 摄取通过一种新的转运机制发生，我们提出， 详细描述。 此外，我们将研究假设 增加的基质ADN浓度是一个启动信号， 随后展开的新陈代谢发展的扩展程序。 一 直接的影响将是刺激（可能是通过大规模行动）的关键 位于基质中的ADP依赖性反应，例如： 氧化 磷酸化，丙酮酸羧化，短链脂肪酸活化， 和瓜氨酸的合成，促进能量的恢复 在代谢调整的关键时期， 出生后 最有趣的是出生后早期的前景 线粒体的增殖通过这种机制调节， 刺激ADN依赖性基质反应， 线粒体生物发生，例如： 心磷脂的线粒体合成， 核酸和蛋白质，以及核编码前体的易位 蛋白质进入线粒体 线粒体增殖反过来可能是 专业化途径的最佳发展的先决条件，如 尿素合成和脂肪酸氧化，所有这些 具有分配给线粒体隔室的核编码酶。 线粒体的增殖也可能是导致 出生后的细胞分裂 这些事件的时间顺序， 机制的细节，和监管的相互关系将在 新生大鼠和兔，在体内和肝细胞中， 在出生后发育的各个阶段制备的线粒体。 给定 分娩时重要的生理信号是pO 2升高 和胰岛素/胰高血糖素减少，呼吸窘迫的影响， 孕妇糖尿病对正常发育的影响将得到特别关注。

The objective is to understand the cellular and biochemical events that lead to successful metabolic adaptation in early postnatal life. We have shown that perinatal changes in insulin/glucagon andd tissue pO2 regulate the sudden net uptake of adenine nucleotides (ADN) from the liver cytosol into the mitochondria, resulting in a large increase in the matrix ATP+ADP+AMP pool size within a few hours after birth. Mitochondrial ADN uptake occurs via a novel transport mechanism that we propose to characterize in detail. In addition we will investigate the hypothesis that the increased matrix ADN concentration is the initiating signal for an extended program of metabolic development that unfolds subsequently. One immediate effect would be the stimulation (probably by mass action) of key ADN-dependent reactions that are localized in the matrix, e.g.: oxidative phosphorylation, pyruvate carboxylation, short chain fatty acid activation, and citrulline synthesis, that promotes the restoration of energy homeostasis during the critical period of metabolic adjustment immediately after birth. Most interesting is the prospect that early postnatal proliferation of mitochondria is regulated by this mechanism via stimulation of the ADN-dependent matrix reactions required for mitochondrial biogenesis, e.g.: mitochondrial synthesis of cardiolipin, nucleic acids, and protein, and translocation of nuclear-encoded precursor proteins into the mitochondria. Mitochondrial proliferation may in turn be a prerequisite for the optimum development of specialized pathways such as gluconeogenesis, urea synthesis, and fatty acid oxidation, all of which have nuclear-encoded enzymes assigned to the mitrochondria compartment. Mitochondrial proliferation may also be permissive for the onset of postnatal cell division. The temporal sequence of these events, their mechanistic details, and regulatory interrelationships will be studied in newborn rats and rabbits, in vivo and in hepatocytes and isolated mitochondria prepared at various stages of postnatal development. Given that the important physiological signals at parturition are increased pO2 and decreased insulin/glucagon, the effect of respiratory distress and maternal diabetes on normal development will receive special attention.