Deschênes Georges, Gonin Sandrine, Zolty Einath, Cheval Lydie, Rousselot Martine, Martin Pierre-Yves, Verbavatz Jean-Marc, Féraille Eric, Doucet Alain
Service de Néphrologie Pédiatrique, Hôpital Armand-Trousseau, Assistance Publique-Hôpitaux de Paris, Paris, France.
Laboratoire de Biologie Intégrée des Cellules Rénales, Service de Biologie Cellulaire, Commissariat à l'Energie Atomique, Gif sur Yvette, France.
J Am Soc Nephrol. 2001 Nov;12(11):2241-2252. doi: 10.1681/ASN.V12112241.
Renal sodium retention is responsible for ascites and edema in nephrotic syndrome. In puromycin aminonucleoside (PAN)-induced nephrosis, sodium retention originates in part from the collecting duct, and it is associated with increased Na,K-ATPase activity in the cortical collecting duct (CCD). The aims of this study were to evaluate whether the outer medullary collecting duct (OMCD) also participates to sodium retention and to determine the mechanisms responsible for stimulation of Na,K-ATPase in CCD. PAN nephrosis increased Na,K-ATPase activity in the CCD but not in OMCD. The two-fold increase of Na,K-ATPase activity in CCD was associated with two-fold increases in the number of alpha and beta Na,K-ATPase subunits mRNA determined by quantitative RT-PCR and of the total amount of Na,K-ATPase alpha subunits estimated by Western blotting. PAN nephrosis also increased two-fold the amount of Na,K-ATPase alpha subunit at the basolateral membrane of CCD principal cells, as determined by Western blotting after biotinylation and streptavidin precipitation and by immunofluorescence. The intracellular pool of latent Na,K-ATPase units also increased in size and was no longer recruitable by vasopressin and cAMP. This unresponsiveness of the intracellular pool of Na,K-ATPase to vasopressin was not the result of any alteration of the molecular and functional expression of the vasopressin V(2) receptor/adenylyl cyclase (AC) complex. It is concluded that PAN nephrosis (1) does not alter sodium reabsorption in OMCD, (2) is associated with increased synthesis and membrane expression of Na,K-ATPase in the CCD, and (3) alters the normal trafficking of intracellular Na,K-ATPase units to the basolateral membrane.
肾钠潴留是肾病综合征中腹水和水肿的原因。在嘌呤霉素氨基核苷（PAN）诱导的肾病中，钠潴留部分源于集合管，并且与皮质集合管（CCD）中Na，K - ATP酶活性增加有关。本研究的目的是评估外髓集合管（OMCD）是否也参与钠潴留，并确定负责刺激CCD中Na，K - ATP酶的机制。PAN肾病增加了CCD中Na，K - ATP酶的活性，但未增加OMCD中的活性。CCD中Na，K - ATP酶活性的两倍增加与通过定量RT - PCR测定的α和βNa，K - ATP酶亚基mRNA数量的两倍增加以及通过蛋白质印迹法估计的Na，K - ATP酶α亚基总量的两倍增加相关。通过生物素化和链霉亲和素沉淀后的蛋白质印迹法以及免疫荧光法测定，PAN肾病还使CCD主细胞基底外侧膜上的Na，K - ATP酶α亚基数量增加了两倍。潜在的Na，K - ATP酶单位的细胞内池大小也增加，并且不再能被血管加压素和cAMP募集。Na，K - ATP酶细胞内池对血管加压素的这种无反应性不是血管加压素V（2）受体/腺苷酸环化酶（AC）复合物的分子和功能表达发生任何改变的结果。得出的结论是，PAN肾病（1）不会改变OMCD中的钠重吸收，（2）与CCD中Na，K - ATP酶的合成增加和膜表达增加有关，并且（3）改变了细胞内Na，K - ATP酶单位向基底外侧膜的正常转运。
