Lower Intestinal and Renal Transport of Ammonia and Amino Acids in Birds: A Test of the Nitrogen Recycling Hypothesis

鸟类中氨和氨基酸的下肠和肾脏转运：氮循环假说的检验

• 批准号: 9870810
• 负责人: Gary Laverty
• 金额: $ 9.54万
• 依托单位: University of Delaware
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-01 至 2002-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9870810&HistoricalAwards=false
• 关键词: Lower; Intestinal; Renal; Transport; Ammonia

9870810 Laverty This proposal will seek to test some of the predictions of a postulated nitrogen recycling system between the lower intestine (colon and ceca) and kidney of birds. This study will examine the aspects specifically related to lower intestinal and renal transport of ammoniagenic substrates, as well as renal ammoniagenesis and secretion. Renal transport properties and ammoniagenesis will be studied by similar techniques, using a recently developed primary cell culture model of the avian renal proximal tubule. This culture system results in flat, confluent monolayers of proximal cells on permeable filter supports, which display morphological, enzymatic and transport characteristics typical of vertebrate proximal tubules. The actual mechanism of ammonia release (tubular secretion) from these cells will be examined, since avian proximal tubules, unlike their mammalian counterparts, do not generate pH gradients across the tubule epithelium. In addition amino acid uptake and ammoniagenesis will be measured under simulated acidotic conditions, y exposing these cell cultures to an acidic environment. These studies will not only test aspects of the nitrogen recycling system, but will also provide new information on avian lower intestinal substrate transport, renal amino acid transport and renal ammoniagenesis, secretion and adaptation to acidosis. The proposed work will be important in furthering an understanding of avian lower intestinal function, renal gluconeogenesis and renal acid-base physiology.

9870810 Laverty该提案将试图测试鸟类下肠（结肠和盲肠）和肾脏之间假定的氮循环系统的一些预测。 本研究将探讨与产氨底物的下肠道和肾脏转运，以及肾脏产氨和分泌有关的方面。 肾脏运输特性和氨的生成将通过类似的技术进行研究，使用最近开发的原代细胞培养模型的禽肾近曲小管。 该培养系统导致在可渗透的过滤器支持物上的近端细胞的平坦、汇合的单层，其显示脊椎动物近端小管的典型形态、酶和运输特征。 将检查这些细胞氨释放（肾小管分泌）的实际机制，因为与哺乳动物对应物不同，禽类近端小管不会在小管上皮上产生pH梯度。 此外，将在模拟酸中毒条件下测量氨基酸摄取和氨生成，将这些细胞培养物暴露于酸性环境。 这些研究不仅将测试氮循环系统的各个方面，而且还将提供关于鸟类下肠道基质转运、肾氨基酸转运和肾氨生成、分泌和对酸中毒的适应的新信息。 本研究对于进一步了解鸟类下消化道功能、肾脏的再生和肾脏的酸碱生理具有重要意义。