SOLUTE AND WATER TRANSPORT IN RENAL EPITHELIA

肾脏含有几种不同的上皮细胞， 聚集功能，负责尿液的形成。 我们正在研究这些上皮细胞在调节 水、尿素、铵、碳酸氢盐、钠 钾和氯。 一般的方法是剖析 从肾脏中分离上皮细胞并研究其体外功能。 对家兔近端小管的研究表明， 铵离子和氨分子的运输。 重碳酸盐的吸收和铵的分泌， 首次在近端直小管中证实了这一点。 老鼠 对家兔粗升支的研究表明， 证明了铵离子的活性重吸收。 研究 家兔皮质集合管的形成表明， 不平衡的pH，增强氨分泌。 外髓集合管的实验 证明了在管腔中的功能性碳酸酐酶， 内条纹段，但不在外条纹段中。 内髓集合管的实验表明 加压素增加了末梢的尿素渗透性 部分，但不是内髓集合的起始部分 管道。 尿素渗透性的增加是由尿素浓度升高介导的。 细胞内环磷酸腺苷，但加压素也增加 胞内钙 内髓实验 集合管显示心房利钠因子抑制 加压素刺激的水渗透性和减少氯化物 磁导率 离体兔乳头表面实验 上皮细胞已经显示出低渗透水渗透性 不受血管加压素影响。

The kidney contains several distinct epithelia that, in their aggregate function, are responsible for formation of the urine. We are studying the roles of these epithelia in the regulation of the excretion of water, urea, ammonium, bicarbonate, sodium, potassium, and chloride. The general approach is to dissect the epithelia from the kidney and to study their functions in vitro. Studies in the proximal tubule of the rabbit have demonstrated transport of both ammonium ions and ammonia molecules. Bicarbonate absorption and ammonium secretion have been demonstrated for the first time in the proximal straight tubule of the rat. Studies in the rabbit thick ascending limb have demonstrated active reabsorption of ammonium ions. Studies in rabbit cortical collecting ducts have shown formation of a disequilibrium pH which enhances ammonia secretion. Experiments in the outer medullary collecting duct have demonstrated functional carbonic anhydrase in the lumen of the inner stripe segment, but not in the outer stripe segment. Experiments in the inner medullary collecting duct have shown that vasopressin increases the urea permeability of the terminal part, but not the initial part of the inner medullary collecting duct. The increase urea permeability is mediated by a rise in intracellular cyclic AMP, but vasopressin also increases intracellular calcium. Experiments in the inner medullary collecting duct have shown that atrial natriuretic factor inhibits vasopressin-stimulated water permeability and reduces chloride permeability. Experiments in isolated rabbit papillary surface epithelium have demonstrated a low osmotic water permeability that is not affected by vasopressin.