Structure of the nephron and sites of action of hormones with special reference to hydro-mineral metabolism in the kidney of the bullfrog.

肾单位的结构和激素的作用位点，特别涉及牛蛙肾脏中的水矿物质代谢。

基本信息

批准号：
02640586
负责人：
UCHIYAMA Minoru
金额：
$ 1.22万
依托单位：
The Nippon Dental University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02640586/
关键词：
Bullfrog Nephron Hormonal receptors Arginine vasotocin Parathyroid hormone Mineral metabolism 賢ネフロン電解質

项目摘要

The present study was projected to elucidate the sites of action for various hormones along the nephrons in the kidney of the bullfrog. Those hormones are arginine vasotocin (AVT), mesotocin (MST) and parathyroid hormone (PTH). On the basis of this study, morphological observation of the kidney was examined by light and electron microscopy and the reconstruction of the nephron was obtained from a serial section of the kidney of a bullfrog. Then, I used a microtechnique that allows hormone-dependent adenylate cyclase activity to be measured in samples containing a localized piece of tubules isolated by microdissection from collagenase-treated kidney tissue.1. MorphologyEach nephron consists of the following parts : renal corpuscle, ciliated neck segment, proximal tubule, ciliated intermediate segment, distal tubule, connecting tubule, and collecting duct. The cellular ultrastructures of the early distal and the connecting tubules have resemblance to those of the mammalian thick ascendin … More g limb and of the cortical collecting tubule, respectively.2. MethodologyCellular production of cAMP in response to hormone was examined in microdissected segments of the nephron.3. Effects of Hormones(1) AVT : The basal levels of cAMP were not significantly different among the segments (renal corpuscle, proximal, distal and connecting tubules). However, the basal levels were higher in spring than in late autumn. When AVT (1 muM) was added to the incubation medium, AVT activated the production of cAMP in both distal and connecting tubules but not in the renal corpuscle and proximal tubule. However, no appreciable responses to AVT were observed in the early distal tubules from frogs collected in late autumn. These results suggest that V_2-type receptors may be present in both distal and connecting tubules of the bullfrog kidney. Seasonal differences may exist with respect to the responsiveness to AVT of the nephrons of the bullfrog.(2) PTH : There was no stimulation of cAMP formation by PTH in both. the proximal and the distall tubules. The lack of hormonal stimulation of cAMP formation observed in both segments of tubules might reflect either the total absence of hormonal receptors associated either a cAMP-generating system in these preparations, their presence in only very small quantity, or the fact that they are not detectable by the methods used in this study.(3) MST and calcitonin : As study of these hormones is now being carried out, enough data to get conclusion are not available. Less

本研究旨在阐明牛蛙肾脏中各种激素的作用部位，这些激素是精氨酸催产素（AVT）、中产素（MST）和甲状旁腺激素（PTH）。通过光学和电子显微镜检查肾脏的形态学观察，并从牛蛙肾脏的连续切片中获得肾单位的重建。然后，我使用了一种微技术，可以在含有通过显微解剖从胶原酶处理的肾组织中分离出的局部小管的样品中测量激素依赖性腺苷酸环化酶活性。形态学每个肾单位由以下部分组成：肾小体、纤毛颈。段、近端小管、纤毛中间段、远端小管、连接小管和集合管早期远端和连接管的细胞超微结构。肾小管分别与哺乳动物的厚上升蛋白肢和皮质集合小管相似。2. 方法在肾单位的显微解剖部分中检查了细胞产生的 cAMP 对激素的影响。3。 AVT：各节段（肾小体、近端、远端和连接小管）cAMP 的基础水平没有显着差异，但基础水平较高。当将 AVT (1 μM) 添加到培养液中时，AVT 会激活远端肾小管和连接肾小管中 cAMP 的产生，但不会激活肾小体和近端肾小管中的 cAMP。但是，没有观察到对 AVT 的明显反应。这些结果表明，V_2 型受体可能存在于牛蛙肾脏的远端肾小管和连接肾小管中。 (2) PTH ：在近端和远端肾小管中均未观察到 PTH 对 cAMP 形成的激素刺激。肾小管的数量可能反映了这些制剂中完全不存在与 cAMP 生成系统片段相关的激素受体，它们的存在量非常小，或者它们不存在的事实(3)MST和降钙素：由于这些激素的研究正在进行，还没有足够的数据来得出结论。