Kudo L H, César K R, Ping W C, Rocha A S
Departamento de Clínica Médica, Faculdade de Medicina, Universidade de São Paulo, Brazil.
Am J Physiol. 1992 Mar;262(3 Pt 2):F338-47. doi: 10.1152/ajprenal.1992.262.3.F338.
The effect of bath fluid hypertonicity on hydraulic conductivity (Lp) and [14C]urea permeability (Pu) of the distal inner medullary collecting duct (IMCD) was studied in the absence and in the presence of vasopressin (VP) using the in vitro microperfusion technique of rat IMCD. In the first three groups of IMCD, we observed that in the absence of VP the Lp was not different from zero when the osmotic gradient was created by hypotonic perfusate and isotonic bath fluid, but it was significantly greater than 1.0 x 10(-6) cm.atm-1.s-1 when the osmotic gradient was created by hypertonic bath and isotonic perfusion fluid. The increase in Lp was observed when the hypertonicity of the bath fluid was produced by the addition of NaCl or raffinose, but no such effect was observed with urea. The stimulated effect of bath fluid hypertonicity on Lp was also observed in the IMCD obtained from Brattleboro homozygous rats in which VP is absent. The NaCl hypertonic bath increased the Pu in the absence of VP. In another series of experiments with VP (10(-10) M) we observed that the hypertonic bath fluid increased in a reversible manner the VP-stimulated Lp of distal IMCD. However, the NaCl hypertonicity of the bath fluid was not able to increase dibutyryladenosine 3',5'-cyclic monophosphate-stimulated Lp. The Pu stimulated by VP (10(-10) M) increased twofold when the bath fluid was hypertonic. Therefore hypertonicity of the peritubular fluid produced by the addition of NaCl or raffinose increases the Lp and Pu in the absence and in the presence of VP. No such effect was noted with the addition of urea.
利用大鼠内髓质集合管（IMCD）的体外微灌注技术，研究了在有无血管加压素（VP）的情况下，浴液高渗对远端IMCD水导率（Lp）和[14C]尿素通透性（Pu）的影响。在前三组IMCD中，我们观察到，在无VP时，当由低渗灌流液和等渗浴液形成渗透梯度时，Lp与零无差异，但当由高渗浴液和等渗灌流液形成渗透梯度时，Lp显著大于1.0×10（-6）cm·atm-1·s-1。当通过添加NaCl或棉子糖使浴液产生高渗时，观察到Lp增加，但添加尿素时未观察到这种效应。在缺乏VP的Brattleboro纯合大鼠的IMCD中也观察到浴液高渗对Lp的刺激作用。在无VP时，NaCl高渗浴增加了Pu。在另一系列使用VP（10（-10）M）的实验中，我们观察到高渗浴液以可逆方式增加了远端IMCD的VP刺激的Lp。然而，浴液的NaCl高渗不能增加二丁酰腺苷3'，5'-环磷酸刺激的Lp。当浴液为高渗时，由VP（10（-10）M）刺激的Pu增加了两倍。因此，添加NaCl或棉子糖产生的肾小管周液高渗在有无VP的情况下均增加了Lp和Pu。添加尿素未观察到这种效应。
