EPITHELIAL TRANSPORT: A MORPHOLOGICAL APPROACH

本申请描述了两个项目。 两者都强调 细胞结构与上皮运输的关系。 1. ADH的作用：扫描和透射电子显微镜 研究。 我们已经能够应用当前的高分辨率技术 扫描和透射电子显微镜（SEM 和 TEM） 抗利尿激素（ADH）的细胞内作用问题。 我们会 使用 SEM 和 TEM 来详细确定端子的结构 蟾蜍膀胱上皮细胞的网，以及特定的丝状 细胞质小管与管腔膜的附着 周围的细胞骨架。 这些小管响应于膜融合 转化为 ADH，并将导水颗粒输送到膜上。 我们有 提出了肾小管融合的“倾斜”机制，并将寻求证据 对于这个机制。 我们将采用单宁酸固定切片，无树脂 我们的 SEM 和 TEM 中的切片和涂有超薄金属膜的切片 部分。 我们将通过以下方式识别特定的细胞骨架成分 光和电磁水平的免疫细胞化学。 我们将隔离并 表征水传导颗粒。 我们将使用我们的技术 对哺乳动物肾脏的研究，强调肾小球细胞骨架 结构。 2.可扩散溶质的放射自显影。 我们的系统的改进 “干”放射自显影术可以研究水溶性物质的运输 尿素等溶质穿过上皮细胞，以及激素和激素的影响 运输抑制剂。 这些研究现在将扩展到两项 新问题：离子和非电解质的旁细胞运输 穿过“渗漏”上皮，以及脉络膜主动转运碘 神经丛。 这两个项目都为解决上皮运输问题带来了新技术。 人们对融合和胞吐作用越来越感兴趣，例如 神经传递和激素分泌； ADH系统正在接受调查 在这个应用程序中提供了最清晰的例子之一 细胞骨架与融合的关系。 在人体肾脏中， 肾小球滤过率似乎受收缩性影响很大 系膜细胞和周围其他细胞元素的特性 基底膜；这些可能会在肾脏疾病中以重要方式发生改变 疾病。 我们的放射自显影研究表明细胞运输以一种新的方式进行 方式，并增加我们对水和电解质运动的理解。

Two projects are described in this application. Both emphasize the relation of cell structure to epithelial transport. 1. The action of ADH: a scanning and transmission electron microscopie study. We have been able to apply current high-resolution techniques in both scanning and transmission electron microscopy (SEM and TEM) to the problem of the intracellular action of antidiuretic hormone (ADH). We will use both SEM and TEM to determine in detail the structure of the terminal web of the toad bladder epithelial cell, and the specific filamentous attachments of the cytoplasmic tubules to the luminal membrane and surrounding cytoskeleton. These tubules fuse to the membrane in response to ADH, and deliver water-conducting particles to the membrane. We have proposed a "tilting" mechanism for tubule fusion, and will seek evidence for this mechanism. We will employ tannic acid-fixed sections, resinless sections and sections coated with ultrathin metal films in our SEM and TEM sections. We will identify specific cytoskeletal components by immunocytochemistry at the light and EM level. We will isolate and characterize the water-conducting particles. We will use our techniques in a study of the mammalian kidney, emphasizing glomerular cytoskeletal structure. 2. Autoradiography of diffusible solutes. Refinements in our system of "dry" autoradiography permit the study of the transport of water-soluble solutes such as urea across epithelia, and the effects of hormones and inhibitory agents on transport. These studies will now be extended to two new problems: the paracellular transport of ions and non-electrolytes across "leaky" epithelia, and the active transport of iodide by the choroid plexus. Both projects bring new techniques to the problem of epithelial transport. There is increasing interest in fusion and exocytosis in such phenomena as neurotransmission and hormone secretion; the ADH system under investigation in this application provides one of the most clear-cut examples of the relationship of the cytoskeleton to fusion. In the human kidney, glomerular filtration appears to be greatly influenced by the contractile properties of the mesangial cell and other cellular elements surrounding the basement membrane; these may be altered in important ways in renal disease. Our autoradiographic studies show cellular transport in a new way, and add to our understanding of water and electrolyte movement.