REGULATION OF INDIVIDUAL NEPHRON FILTRATION RATES

长期目标是增加对监管的了解， 肾单位的功能，通过利用鸟类肾脏的独特结构， 沙漠啮齿动物肾脏的高度特化结构， 哺乳动物和鸟类肾单位的特殊运输特性。 禽 肾脏有类似爬行动物肾单位的肾单位， 肾小球（单个毛细血管袢）功能独立， 不直接有助于集中机制，并且可以停止 在某些情况下完全过滤;肾单位类似 哺乳动物的肾单位在集中机制中一起起作用， 通常不会停止过滤，但可能会改变其过滤速率;以及 动脉和门静脉的血液供应 肾源性尿崩症 沙漠啮齿动物的肾脏 髓质肾单位比浅表皮质大几倍 肾单位和很长的乳头。 这种结构上的异质性 肾单位的结构异质性介于 在鸟类肾脏和实验室老鼠的肾脏中。 主要目标包括 研究：1）肾小球结构和功能，包括定量 鸟类肾脏的超微结构和过滤压力;以及2） 髓质功能和浓缩机制，包括氨基酸 哺乳动物髓质肾单位的转运，氨基酸在 哺乳动物的髓质功能，以及鸟类的集中缺陷， 遗传性肾源性糖尿病计算机辅助定量 过滤屏障和可用面积的超微结构分析 用于过滤将用于检查简单的禽肾小球。 体内 微穿刺压力测量将有助于确定鸟类肾小球 不同利尿状态下与结构相关的滤过动力学。 体内微穿刺和连续微输注，体外 微灌注和微穿刺样品和肾脏的氨基酸分析 切片提取物将用于进一步确定氨基酸重吸收 远侧的Henle's lops的尖端的延髓肾单位，回收， 尿中用于细胞渗透和容量调节的氨基酸 在实验室大鼠和沙漠啮齿动物中的浓度。 体内清除 测定和门静脉输注和体外灌注分离的 鸟类收集管和酶活性的测定在这些 收集管将用于确定鸡的肾缺陷 肾性尿崩症

The long-term objective is to increase understanding of the regulation of nephron function by exploiting the unique structure of avian kidneys, the highly specialized structure of kidneys of desert rodents, and the specialized transport properties of mammalian and avian nephrons. Avian kidneys have nephrons resembling reptilian nephrons with very simple glomeruli (single capillary loop) that function independently of each, do not contribute directly to the concentrating mechanism, and can cease filtering altogether under some circumstances; nephrons resembling mammalian nephrons that function together in the concentrating mechanism, do not normally cease filtering, but may alter their filtration rates; and both arterial and portal venous blood supplies One strain of chickens has nephrogenic diabetes insipidus. Kidneys of desert rodents have juxtamedullary nephrons several times larger than superficial cortical nephrons and a very long papilla. This structural heterogeneity of nephrons is intermediate between the structural heterogeneity of nephrons in avian kidneys and laboratory rat kidneys. The primary goals involve studies of: 1) glomerular structure and function, including quantitative ultrastructure and filtration will pressures in avian kidneys; and 2) medullary function and concentrating mechanism, including amino acid transport by juxtamedullary mammalian nephrons, the role of amino acids in mammalian medullary function, and concentrating defect(s) in birds with genetic nephrogenic diabetes inipidus. Computer-assisted quantitative ultrastructural analysis of the filtration barrier and the area available for filtration will be used to examine simple avian glomerulus. In vivo micropuncture pressure measurements will help define avian glomerular filtration dynamics in relation to structure in varying diuretic states. In vivo micropuncture and continuous microinfusion, in vitro microperfusion, and amino acid analyses of micropuncture samples and kidney slice extracts will be used to further define amino acid reabsorption distal to the tips of Henle's lops of juxtamedullary nephrons, recycling of amino acids for cellular osmotic and volume regulation during urine concentration in laboratory rats and desert rodents. In vivo clearance determinations and portal infusions and in vitro perfusions of isolated avian collecting ducts and determinations of enzyme activities in these collecting ducts will be used to define the renal defect(s) in chickens with nephrogenic diabetes insipidus.