UREA TRANSPORT AND THE URINARY CONCENTRATING MECHANISM

尿素运输和尿液浓缩机制

• 批准号: 4694524
• 负责人: M A KNEPPER
• 金额: --
• 依托单位: NATIONAL HEART, LUNG, AND BLOOD INSTITUTE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/4694524
• 关键词: active transport; arginine vasopressin; biological fluid transport; body fluid osmolarity; colorimetry; diuresis; epithelium; ion transport; kidney metabolism; mathematical model; membrane permeability; model design /development; radiotracer; renal medulla; renal tubular transport; tissue /cell culture; urea

Studies of isolated renal epithelia and mathematical modelling studies are being carried out to investigate the role of urea in the concentrating mechanism and to define the mechanism of concentration in the inner medulla. The inner medullary collecting duct was found to be heterogenous with respect to urfea permeability. Collecting ducts from the outer third of the inner medulla have a low permeability to urea like those from the medullary rays and outer medulla. In contrast, collecting ducts from the inner two-thirds of the inner medullary collecting duct have an extremely high permeability to urea, 40 x 10-5 cm/s. This pattern of collecting duct urea permeabilities maximizes the axial urea gradient in the inner medulla by delaying urea absorption to near the papillary tip where the effective blood flow is lowest. The papillary surface epithelium was found to have a low permeability to urea (1 x 10-5 cm/s) and a small surface area relative to inner medullary collecting ducts. It is concluded that urea transport across the papillary epithelium is unlikely to contribute significantly to urea delivery to the inner medullary interstitium.

分离肾上皮的研究和数学模型的研究