ION TRANSPORT IN THE HUMAN PLACENTA

胎儿的生长依赖于胎盘的营养供应 来自母体循环，包括钠， 钾和氯。 除了作为基本要素外， 对于胎儿的发育，这些离子的梯度形成跨越 合胞体滋养层的微绒毛膜和基底膜 扮演着几个重要的角色。 跨膜离子梯度 推动关键营养物质如钙的上坡运输， 磷酸盐和氨基酸进入胎儿循环。 他们 还参与细胞内pH和体积等功能 调控 本提案中的研究旨在阐明 胎盘中的离子转运系统及其与 供应胎儿生长的基质。 调查将使用 从微绒毛制备质膜囊泡， 足月人胎盘合体滋养层基底膜。 实验的目的是识别和表征离子 钠、钾、氯、碳酸氢盐和 H+/OH-在两种膜上。 荧光和 将采用放射性标记示踪方法测量 膜离子传输动力学和导电特性。 钙、磷的母胎转运途径 和氨基酸将被定义和离子梯度的耦合 运输这些必需的胎儿营养素将是 分析了 该项目的最后一项内容将是调查 细胞内钙离子浓度 控制胎盘膜离子渗透性。 在短期内，这些研究将提供重要的 生理信息的方式，其中主要离子， 磷酸钙和氨基酸被输送到胎儿体内 这些研究的长期目标是确定 胎盘的功能，包括转运过程， 病理事件如缺氧或局部缺血 或胎盘离子环境的慢性紊乱。

Fetal growth is dependent on the placental supply of nutrients derived from the maternal circulation, including sodium, potassium and chloride. In addition to being essential elements for fetal development, gradients of these ions formed across the microvillous and basal membranes of the syncytiotrophoblast perform several important roles. Transmembrane ion gradients drive the uphill transport of key nutrients such as calcium, phosphate and the amino acids into the fetal circulation. They are also involved in functions such as intracellular pH and volume regulation. The studies in this proposal are designed to elucidate the major ion transport systems in the placenta and their coupling to the supply of substrates for fetal growth. The investigations will use plasma membrane vesicles prepared from the microvillous and basal membranes of term, human placental syncytiotrophoblast. The experiments are designed to identify and characterize the ion transporters for sodium, potassium, chloride, bicarbonate and H+/OH- on both membranes. A combination of fluorescence and radiolabelled tracer methods will be employed to measure the kinetic and conductive characteristics of membrane ion transport. The pathways for the maternofetal transfer of calcium, phosphate and amino acids will be defined and the coupling of ion gradients to the transport of these essential fetal nutrients will be analyzed. The final element in the project will be investigation of the method by which the intracellular calcium concentration controls placental membrane ion permeabilities. Over the short term, these studies will provide important physiological information on the manner in which the major ions, calcium phosphate and the amino acids are channeled to the fetus. The long term goals of these studies are to determine how placental functions, including transfer processes, are affected by pathological events such as hypoxia or ischemia which cause acute or chronic disturbances in the placental ionic environment.