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。 大鼠皮质集合管实验表明， 心房钠尿因子（ANF）直接抑制NaCl和液体 吸收 大鼠内髓集合管实验 显示ANF显著抑制加压素刺激的渗透压 水渗透性的“后环AMP”的影响。 数学 模拟研究表明，ANF在 收集管道系统在数量上足以说明 肾脏NaCl和液体排泄增加。 离体灌流 小管研究表明，加压素刺激的尿素 大鼠内髓集合管中的运输是饱和的， 被尿素的化学类似物抑制，被 根皮素，是独立的加压素刺激的水 渗透途径 这些结果支持了尿素 通过专门的尿素载体或通道进行输送。 终末内髓集合管的实验 证明管腔酸化，这是增加了体内 酸中毒或脱氧皮质酮给药和加压素 in vivo. 在显微解剖的大鼠集合管中进行的实验 表明终末内髓集合管 具有显著的Na-K-ATP酶活性， 饮食NaCl限制或盐皮质激素给药。 在离体兔乳头状表面上皮中的实验， 表明加压素减少被动氯化物 磁导率

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. Experiments in the cortical collecting duct of rat showed that atrial natriuretic factor (ANF) directly inhibits NaCl and fluid absorption. Experiments in rat inner medullary collecting ducts revealed that ANF markedly inhibits vasopressin-stimulated osmotic water permeability by a "post-cyclic AMP" effect. Mathematical modelling studies have demonstrated that ANF effects in the collecting duct system are quantitatively sufficient to account for increases in renal NaCl and fluid excretion. Isolated perfused tubule studies have demonstrated that vasopressin-stimulated urea transport in the rat inner medullary collecting duct is saturable, is inhibited by chemical analogs of urea, is inhibited by phloretin, and is independent of the vasopressin-stimulated water permeability pathway. These results support the view that the urea transport occurs via a specialized urea carrier or channel. Experiments in terminal inner medullary collecting ducts have demonstrated luminal acidification, which is increased by in vivo acidosis or deoxycorticosterone administration and by vasopressin in vivo. Experiments in microdissected rat collecting ducts have demonstrated that the terminal inner medullary collecting duct possesses substantial Na-K-ATPase activity which is enhanced by dietary NaCl restriction or mineralocorticoid administration. Experiments in isolated rabbit papillary surface epithelium have demonstrated that vasopressin reduces passive chloride permeability.