MEMBRANE PROCESSES MEDIATING NACL REABSORPTION

介导致密上皮细胞钠重吸收的离子通道将被破坏。 特征，以及调节这些通道的机制 将被调查。 将使用的主要模型组织为 大鼠肾皮质集合小管。 顶膜通道， 对钠离子有选择性，对利尿剂阿米洛利敏感， 研究使用膜片钳技术，以确定离子电流通过 个别渠道。 这些通道的生物物理性质将是 通过评估通道对各种阳离子的选择性来探索， 在不同渗透物浓度下通道的电导率 离子，自发通道开放和关闭的速率，以及 保钾利尿剂抑制通道功能的能力。 的 包括激素在内的各种因素对通道的调节 （醛固酮和ADH），外部和内部离子浓度（Ca，H和 钠），组织的代谢状态，以及酶的活性， 甲基化和磷酸化膜蛋白也将被研究。 最后，将使用特定于组的试剂来发现化学物质 重要氨基酸的性质，其支配传导和调节 的渠道。 该项目将增加对 上皮细胞重吸收NaCl的重要过程，其中缺陷 与囊性纤维化、充血性心脏病等疾病有关 失败和腹泻。

Ion channels that mediate Na reabsorption by tight epithelia will be characterized, and the mechanisms by which these channels are regulated will be investigated. The major model tissue to be used will be the cortical collecting tubule of rat kidney. Apical membrane channels which are selective for Na ions and sensitive to the diuretic amiloride will be studied using the patch-clamp technique to identify ionic currents through individual channels. The biophysical nature of theses channels will be explored by assessing the selectivity of the channels for various cations, the conductance of the channels at different concentrations of permeant ions, the rates of spontaneous channel opening and closing, and the details of the ability of K-sparing diuretics to inhibit channels function. The regulation of the channels by various factors including hormones (aldosterone and ADH), external and internal ion concentrations (Ca, H and Na), the metabolic state of the tissue, and the activities of enzymes which methylate and phosphorylate membrane proteins will also be investigated. Finally, group-specific reagents will be employed to discover the chemical nature of important amino acids which govern the conductance and regulation of the channels. This project will increase the understanding of the importance process of NaCl reabsorption by epithelia, defects in which have been implicated in such diseases as cystic fibrosis, congestive heart failure and diarrhea.