ION TRANSPORT IN THE HUMAN PLACENTA

胎儿的生长发育依赖于胎盘的营养物质供应 从母体循环中提取，包括钠， 钾和氯化物。除了是必不可少的要素之外 对于胎儿发育，这些离子的梯度形成于 合体滋养细胞的微绒毛和基底膜 扮演几个重要的角色。跨膜离子梯度 推动钙等关键营养素的上山运输， 磷酸盐和氨基酸进入胎儿循环。他们 也参与了细胞内pH和体积等功能 监管。 本提案中的研究旨在阐明主要的 胎盘中的离子转运系统及其与细胞的偶联 为胎儿生长提供底物。调查将利用 从微绒毛和微绒毛制备的质膜囊泡 足月基膜，人胎盘合体滋养层细胞。 这些实验的目的是识别和表征离子。 钠、钾、氯化物、碳酸氢盐和 H+/OH-在两种膜上。一种荧光和荧光的组合 将使用放射性标记示踪方法来测量 膜离子传输的动力学和电导特性。 钙、磷的母胎转运途径 氨基酸的定义和离子梯度的耦合 来运输这些必要的胎儿营养物质 分析过了。该项目的最后一项内容是对 测定细胞内钙离子浓度的方法 控制胎盘膜离子的通透性。 短期内，这些研究将提供重要的 关于主要离子， 磷酸钙和氨基酸被输送到胎儿。 这些研究的长期目标是确定如何 胎盘功能，包括转移过程，受到以下因素的影响 病理事件，如缺氧或缺血，导致急性 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.