The investigation of the mechanisms and the rapy of renal edema from the acpect of cell porality.

我们使用特异性多克隆抗体研究了V2加压素（抗利尿激素）受体沿着肾单位的免疫组织化学定位。V_2受体分布于部分粗大的升支及所有的前髓和内髓集合管细胞。因此，为了了解管腔V2受体在终末IMCD中的功能作用，我们采用离体灌流的大鼠终末IMCD研究了加压素对渗透水通透性（Pf）、尿素通透性（Pu）和cAMP积累的管腔效应。在没有浴加压素的情况下的Pf和Pu。与此相反，在存在血管加压素的情况下，管腔加压素通过V1 a或催产素受体以及通过V2受体减少终末IMCD管腔膜上cAMP的积聚，抑制Pf和Pu 30-65%，因此，管腔加压素在终末IMCD中起利尿激素而不是抗利尿激素的作用。

We investigated immunohistochemical localization of V2 vasopressin (antidiuretic hormone) receptor along the nephron using a specific polyclonal antibody. V2 receptor was present in some of thick ascending limbs and all of pricipal and inner medullary collecting duct (IMCD) cells. Not only basolateral but also luminal membrane was stained by the antibody in collecting ducts, especially in terminal IMCD.Therefore, to learn the functional role of luminal V2 receptor in terminal IMCD,we investigated the luminal effects of vasopressin on osmotic water permeability (Pf), urea permeability (Pu), and cAMP accumulation using isolated perfused rat terminal IMCD.Luminal vasopressin caused a small increase in cAMP accumulation, Pf and Pu in the absence of bath vasopressin. In contrast, luminal vasopressin inhibited Pf and Pu by 30-65% in the presence of bath vasopressin by decreasing cAMP accumulation via V1a or oxytocin receptors and by an unknown mechanism via V2 receptors in the luminal membrane of terminal IMCD.Therefore, luminal vasopressin acts as an diuretic hormone rather than antidiuretic hormone in terminal IMCD.