Nitric oxide reduces Cl- absorption in the mouse cortical collecting duct through an ENaC-dependent mechanism.

Since nitric oxide (NO) participates in the renal regulation of blood pressure, in part, by modulating transport of Na(+) and Cl(-) in the kidney, we asked whether NO regulates net Cl(-) flux (JCl) in the cortical collecting duct (CCD) and determined the transporter(s) that mediate NO-sensitive Cl(-) absorption. Cl(-) absorption was measured in CCDs perfused in vitro that were taken from aldosterone-treated mice. Administration of an NO donor (10 μM MAHMA NONOate) reduced JCl and transepithelial voltage (VT) both in the presence or absence of angiotensin II. However, reducing endogenous NO production by inhibiting NO synthase (100 μM N(G)-nitro-l-arginine methyl ester) increased JCl only in the presence of angiotensin II, suggesting that angiotensin II stimulates NO synthase activity. To determine the transport process that mediates NO-sensitive changes in JCl, we examined the effect of NO on JCl following either genetic ablation or chemical inhibition of transporters in the CCD. Since the application of hydrochlorothiazide (100 μM) or bafilomycin (5 nM) to the perfusate or ablation of the gene encoding pendrin did not alter NO-sensitive JCl, NO modulates JCl independent of the Na(+)-dependent Cl(-)/HCO3(-) exchanger (NDCBE, Slc4a8), the A cell apical plasma membrane H(+)-ATPase and pendrin. In contrast, both total and NO-sensitive JCl and VT were abolished with application of an epithelial Na(+) channel (ENaC) inhibitor (3 μM benzamil) to the perfusate. We conclude that NO reduces Cl(-) absorption in the CCD through a mechanism that is ENaC-dependent.

ENaC inhibition stimulates Cl- secretion in the mouse cortical collecting duct through an NKCC1-dependent mechanism.

In cortical collecting ducts (CCDs) perfused in vitro, inhibiting the epithelial Na(+) channel (ENaC) reduces Cl(-) absorption. Since ENaC does not transport Cl(-), the purpose of this study was to determine how ENaC modulates Cl(-) absorption. Thus, Cl(-) absorption was measured in CCDs perfused in vitro that were taken from mice given aldosterone for 7 days. In wild-type mice, we observed no effect of luminal hydrochlorothiazide on either Cl(-) absorption or transepithelial voltage (V(T)). However, application of an ENaC inhibitor [benzamil (3 μM)] to the luminal fluid or application of a Na(+)-K(+)-ATPase inhibitor to the bath reduced Cl(-) absorption by ∼66-75% and nearly obliterated lumen-negative V(T). In contrast, ENaC inhibition had no effect in CCDs from collecting duct-specific ENaC-null mice (Hoxb7:CRE, Scnn1a(loxlox)). Whereas benzamil-sensitive Cl(-) absorption did not depend on CFTR, application of a Na(+)-K(+)-2Cl(-) cotransport inhibitor (bumetanide) to the bath or ablation of the gene encoding Na(+)-K(+)-2Cl(-) cotransporter 1 (NKCC1) blunted benzamil-sensitive Cl(-) absorption, although the benzamil-sensitive component of V(T) was unaffected. In conclusion, first, in CCDs from aldosterone-treated mice, most Cl(-) absorption is benzamil sensitive, whereas thiazide-sensitive Cl(-) absorption is undetectable. Second, benzamil-sensitive Cl(-) absorption occurs by inhibition of ENaC, possibly due to elimination of lumen-negative V(T). Finally, benzamil-sensitive Cl(-) flux occurs, at least in part, through transcellular transport through a pathway that depends on NKCC1.

A transvesical approach to mullerian duct remnants

Surgical extirpation is the treatment of choice for symptomatic mullerian duct remnants (prostatic utricle, PU), and several surgical approaches have been described for the treatment of this pathology. A group of 11 patients with symptomatic PU were observed and treated. Associated anomalies included proximal or penoscrotal hypospadias in all patients and cryptorchidism in 9 (81.8%). In all cases the PU needed surgical correction, as the patients had recurring symptomatology. Surgery was carried out transvesically in 10 (91%) cases and in 1 a perineal approach was used. There were no surgical complications, and at follow-up all patients showed complete resolution of the symptoms. We believe the transvesical approach, compared to other techniques, is more advantageous in the treatment of this pathology, as it permits excellent exposure, ease of surgery, good reconstruction, and good functional results with no sequelae.

Nadolol plus isosorbide mononitrate alone or associated with band ligation in the prevention of recurrent bleeding: A multicenter randomized controlled trial.

Background and aims: Previous clinical trials suggest that adding non-selective beta-blockers improves the efficacy of endoscopic band ligation (EBL) in the prevention of recurrent bleeding, but no study has evaluated whether EBL improves the efficacy of beta-blockers + isosorbide-5-mononitrate. The present study was aimed at evaluating this issue in a multicentre randomised controlled trial (RCT) and to correlate changes in hepatic venous pressure gradient (HVPG) during treatment with clinical outcomes. Methods: 158 patients with cirrhosis, admitted because of variceal bleeding, were randomised to receive nadolol+isosorbide-5-mononitrate alone (Drug: n=78) or combined with EBL (Drug+EBL; n=80). HVPG measurements were performed at randomisation and after 4¿6 weeks on medical therapy. Results: Median follow-up was 15 months. One-year probability of recurrent bleeding was similar in both groups (33% vs 26%: p=0.3). There were no significant differences in survival or need of rescue shunts. Overall adverse events or those requiring hospital admission were significantly more frequent in the Drug+EBL group. Recurrent bleeding was significantly more frequent in HVPG non-responders than in responders (HVPG reduction ¿20% or ¿12 mm Hg). Among non-responders recurrent bleeding was similar in patients treated with Drugs or Drugs+EBL. Conclusions: Adding EBL to pharmacological treatment did not reduce recurrent bleeding, the need for rescue therapy, or mortality, and was associated with more adverse events. Furthermore, associating EBL to drug therapy did not reduce the high rebleeding risk of HVPG non-responders.

Probe-specific mixed-model approach to detect copy number differences using multiplex ligation-dependent probe amplification (MLPA)

Background: MLPA method is a potentially useful semi-quantitative method to detect copy number alterations in targeted regions. In this paper, we propose a method for the normalization procedure based on a non-linear mixed-model, as well as a new approach for determining the statistical significance of altered probes based on linear mixed-model. This method establishes a threshold by using different tolerance intervals that accommodates the specific random error variability observed in each test sample.Results: Through simulation studies we have shown that our proposed method outperforms two existing methods that are based on simple threshold rules or iterative regression. We have illustrated the method using a controlled MLPA assay in which targeted regions are variable in copy number in individuals suffering from different disorders such as Prader-Willi, DiGeorge or Autism showing the best performace.Conclusion: Using the proposed mixed-model, we are able to determine thresholds to decide whether a region is altered. These threholds are specific for each individual, incorporating experimental variability, resulting in improved sensitivity and specificity as the examples with real data have revealed.

A nasopalatine duct cyst in a 7-year-old child.

The nasopalatine duct cyst (NPDC) is a developmental cyst of the anterior palate's midline, usually presenting as an asymptomatic swelling located just behind the maxillary central incisors. It is the most common non-odontogenic cyst of the jaws but is seen rarely in children. The purpose of this paper was to report an unusual case of nasopalatine duct cyst in a 7-year-old boy who presented with a slow-growing, slight swelling of the anterior palate together with malpositioned permanent maxillary central incisors. Although rare in children, NPCD should be included in the differential diagnosis of anterior palate swelling, particularly if associated with malpositioned maxillary central incisors.

Laparoscopic Pancreatic Enucleation With End-to-End Pancreatic Duct Reconstruction.

BACKGROUND: Laparoscopic enucleation for neuroendocrine pancreatic tumors has become a feasible technique, with a reported incidence of pancreatic fistula ranging from 13 to 29 %.1 (-) 3 This report describes the first successful case of laparoscopic pancreatic enucleation with resection of the main pancreatic duct followed by end-to-end anastomosis. METHODS: A 41-year-old woman was admitted to the authors' hospital for repeated syncope. Hypoglycemia also was noted. A contrast-enhanced computed tomography examination showed a highly enhanced tumor measuring 22 mm in diameter on the ventral side of the pancreatic body adjacent to the main pancreatic duct. The patient's blood insulin level was elevated, and her diagnosis was determined to be pancreatic insulinoma. Laparoscopic pancreatic enucleation was performed. Approximately 2 cm of the main pancreatic duct was segmentally resected, and a short stent (Silicone tube: Silastic, Dow Corning Corporation, Midland, MI) was inserted. The direct anastomosis of the main pancreatic duct was performed using four separate sutures with an absorbable monofilament (6-0 PDS). RESULTS: The operation time was 166 min, and the estimated blood loss was 100 mL. The postoperative course was uneventful, and the patient was discharged from hospital on postoperative day 7. The pathologic findings showed a well-differentiated insulinoma and a negative surgical margin. A computed tomography examination performed 1 month after the operation showed a successful anastomosis with a patent main pancreatic duct. CONCLUSIONS: Laparoscopic segmental resection of the main pancreatic duct and end-to-end anastomosis can be performed safely with the insertion of a short stent. This technique also can be used for a central pancreatectomy.

Nasopalatine duct cyst: report of 22 cases and review of the literature

Objectives: Nasopalatine duct cysts (NPDCs) are the most common developmental, epithelial and non-odontogenic cysts of the maxillae. The present study describes the clinicopathological characteristics of 22 NPDCs and discusses their etiology, incidence, treatment and prognosis, with a review of the literature on the subject. Study design: A retrospective observational study was made comprising a period of 36 years (1970-2006), and yielding a series of 22 patients with histopathological confirmation of NPDC. Surgical treatment was carried out under local anesthesia and comprised the dissection and removal of the cyst adopting a usually palatine approach, with the preparation of an enveloping flap from 1.4 to 2.4. Results: No statistically significant correlation was observed between the size of the lesion and patient age, although the size of the cyst differed according to patient gender, with a mean NPDC diameter of 16 mm in males and 12 mm in females. In no case did we observe root reabsorption or loss of vitality of the upper incisors following surgery. The X-ray image was rounded in 15 cases and heart-shaped in the remaining 7 cases. In the majority of cases panoramic X-rays and periapical and occlusal X-rays sufficed to identify the lesion, though computed tomography was used in cases of doubt. Conclusions: The etiology of NPDC is unclear. Simple surgical resection is recommended, followed by clinical and radiological control to ensure correct resolution of the case.

Nasopalatine duct cyst: report of 22 cases and review of the literature

Objectives: Nasopalatine duct cysts (NPDCs) are the most common developmental, epithelial and non-odontogenic cysts of the maxillae. The present study describes the clinicopathological characteristics of 22 NPDCs and discusses their etiology, incidence, treatment and prognosis, with a review of the literature on the subject. Study design: A retrospective observational study was made comprising a period of 36 years (1970-2006), and yielding a series of 22 patients with histopathological confirmation of NPDC. Surgical treatment was carried out under local anesthesia and comprised the dissection and removal of the cyst adopting a usually palatine approach, with the preparation of an enveloping flap from 1.4 to 2.4. Results: No statistically significant correlation was observed between the size of the lesion and patient age, although the size of the cyst differed according to patient gender, with a mean NPDC diameter of 16 mm in males and 12 mm in females. In no case did we observe root reabsorption or loss of vitality of the upper incisors following surgery. The X-ray image was rounded in 15 cases and heart-shaped in the remaining 7 cases. In the majority of cases panoramic X-rays and periapical and occlusal X-rays sufficed to identify the lesion, though computed tomography was used in cases of doubt. Conclusions: The etiology of NPDC is unclear. Simple surgical resection is recommended, followed by clinical and radiological control to ensure correct resolution of the case.

Regulation of sodium transport in the cortical collecting duct : physiological role of GILZ in vitro and in vivo : characterisation of Na+ transport in the mCCDcl1 cell line

SUMMARY Regulation of sodium excretion by the kidney is a key mechanism in the long term regulation of blood pressure, and when altered it constitutes a risk factor for the appearance of arterial hypertension. Aldosterone, which secretion depends upon salt intake in the diet, is a steroid hormone that regulates sodium reabsorption in the distal part of the nephron (functional unit of the kidney) by modulating gene transcription. It has been shown that it can act synergistically with the peptidic hormone insulin through the interaction of their signalisation pathways. Our work consisted of two distinct parts: 1) the in vitro and in vivo characterisation of Glucocorticoid-Induced Leucine Zipper (GILZ) (an aldosterone-induced gene) mechanism of action; 2) the in vitro characterisation of insulin mechanism of action and its interaction with aldosterone. GILZ mRNA, coded by the TSC22D3 gene, is strongly induced by aldosterone in the cell line of principal cells of the cortical collecting duct (CCD) mpkCCDc14, suggesting that GILZ is a mediator of aldosterone response. Co-expression of GILZ and the amiloride-sensitive epithelial sodium channel ENaC in vitro in the Xenopus oocyte expression system showed that GILZ has no direct effect on the ENaC-mediated Na+ current in basal conditions. To define the role of GILZ in the kidney and in other organs (colon, heart, skin, etc.), a conditional knock-out mouse is being produced and will allow the in vivo study of its role. Previous data showed that insulin induced a transepithelial sodium transport at supraphysiological concentrations. Insulin and the insulin-like growth factor 1 (IGF-1) are able to bind to each other receptor with an affinity 50 to 100 times lower than to their cognate receptor. Our starting hypothesis was that the insulin effect observed at these supraphysiological concentrations is actually mediated by the IGF receptor type 1 (IGF-1R). In a new cell line that presents all the characteristics of the principal cells of the CCD (mCCDc11) we have shown that both insulin and IGF-1 induce a physiologically significant increase of Na+ transport through the activation of IGF-1R. Aldosterone and insulin/IGF-1 have an additive effect on Na+ transport, through the activation of the PI3-kinase (PI3-K) pathway and the phosphorylation of the serum- and glucocorticoid-induced kinase 1 (Sgk1) by the IGF-1R, and the induction of Sgk1 expression by aldosterone. Thus, Sgk1 integrates IGF-1/insulin and aldosterone effects. We suggest that IGF-1 is physiologically relevant in the modulation of sodium balance, while insulin can only regulate Na+ transport at supraphysiological conditions. Both hormones would bind to the IGF-1R and induce Na+ transport by activating the PI3-K PDK1/2 - Sgk1 pathway. We have shown for the first time that Sgk1 is expressed and phosphorylated in principal cells of the CCD in basal conditions, although the mechanism that maintains Sgk1 phosphorylation is not known. This new role for IGF-1 suggests that it could be a salt susceptibility gene. In effect, IGF-1 stimulates Na+ and water transport in the kidney in vivo. Moreover, 35 % of the acromegalic patients (overproduction of growth hormone and IGF-1) are hypertensives (higher proportion than in normal population), and genetic analysis suggest a link between the IGF-1 gene locus and blood pressure. RÉSUMÉ La régulation de l'excrétion rénale de sodium (Na+) joue un rôle principal dans le contrôle à long terme de la pression sanguine, et ses altérations constituent un facteur de risque de l'apparition d'une hypertension artérielle. L'aldosterone, dont la sécrétion dépend de l'apport en sel dans la diète, est une hormone stéroïdienne qui régule la réabsorption de Na+ dans la partie distale du nephron (unité fonctionnelle du rein) en contrôlant la transcription de gènes. Elle peut agir de façon synergistique avec l'hormone peptidique insuline, probablement via l'interaction de leurs voies de signalisation cellulaire. Le but de notre travail comportait deux volets: 1) caractériser in vitro et in vivo le mécanisme d'action du Glucocorticoid Induced Leucine Zipper (GILZ) (un gène induit par l'aldosterone); 2) caractériser in vitro le mécanisme d'action de l'insuline et son interaction avec l'aldosterone. L'ARNm de GILZ, codé par le gène TSC22D3, est induit par l'aldosterone dans la lignée cellulaire de cellules principales du tubule collecteur cortical (CCD) mpkCCDc14, suggérant que GILZ est un médiateur potentiel de la réponse à l'aldosterone. La co-expression in vitro de GILZ et du canal à Na+ sensible à l'amiloride ENaC dans le système d'expression de l'oocyte de Xénope a montré que GILZ n'a pas d'effet sur les courants sodiques véhiculées par ENaC en conditions basales. Une souris knock-out conditionnelle de GILZ est en train d'être produite et permettra l'étude in vivo de son rôle dans le rein et d'autres organes. Des expériences préliminaires ont montré que l'insuline induit un transport transépithelial de Na+ à des concentrations supraphysiologiques. L'insuline et l'insulin-like growth factor 1 (IGF-1) peuvent se lier à leurs récepteurs réciproques avec une affinité 50 à 100 fois moindre qu'à leur propre récepteur. Nous avons donc proposé que l'effet de l'insuline soit médié par le récepteur à l'IGF type 1 (IGF-1R). Dans une nouvelle lignée cellulaire qui présente toutes les caractéristiques des cellules principales du CCD (mCCDc11) nous avons montré que les deux hormones induisent une augmentation physiologiquement significative du transport du Na+ par l'activation des IGF-1 R. Aldosterone et insuline/IGF-1 ont un effet additif sur le transport de Na+, via l'activation de la voie de la PI3-kinase et la phosphorylation de la serum- and glucocorticoid-induced kinase 1 (Sgk1) par l'IGF-1R, dont l'expression est induite par l'aldosterone. Sgk1 intègre les effets de l'insuline et l'aldosterone. Nous proposons que l'IGF-1 joue un rôle dans la modulation physiologique de la balance sodique, tandis que l'insuline régule le transport de Na+ à des concentrations supraphysiologiques. Les deux hormones agissent en se liant à l'IGF-1R et induisent le transport de Na+ en activant la cascade de signalisation PI3-K - PDK1/2 - Sgk1. Nous avons montré pour la première fois que Sgk1 est exprimée et phosphorylée dans des conditions basales dans les cellules principales du CCD, mais le mécanisme qui maintient sa phosphorylation n'est pas connu. Ce nouveau rôle pour l'IGF-1 suggère qu'il pourrait être un gène impliqué de susceptibilité au sel. Aussi, l'IGF-1 stimule le transport rénal de Na+ in vivo. De plus, 35 % des patients atteints d'acromégalie (surproduction d'hormone de croissance et d'IGF-1) sont hypertensifs (prévalence plus élevée que la population normale), et des analyses génétiques suggèrent un lien entre le locus du gène de l'IGF-1 et la pression sanguine. RÉSUMÉ GRAND PUBLIC Nos ancêtres se sont génétiquement adaptés pendant des centaines de millénaires à un environnement pauvre en sel (chlorure de sodium) dans la savane équatoriale, où ils consommaient moins de 0,1 gramme de sel par jour. On a commencé à ajouter du sel aux aliments avec l'apparition de l'agriculture (il y a 5000 à 10000 années), et aujourd'hui une diète omnivore, qui inclut des plats préparés, contient plusieurs fois la quantité de sodium nécessaire pour notre fonction physiologique normale (environ 10 grammes par jour). Le corps garde sa concentration constante dans le sang en s'adaptant à une consommation très variable de sel. Pour ceci, il module son excrétion soit directement, soit en sécrétant des hormones régulatrices. Le rein joue un rôle principal dans cette régulation puisque l'excrétion urinaire de sel change selon la diète et peut aller d'une quantité dérisoire à plus de 36 grammes par jour. L'attention qu'on prête au sel est liée à sa relation avec l'hypertension essentielle. Ainsi, le contrôle rénal de l'excrétion de sodium et d'eau est le principal mécanisme dans la régulation de la pression sanguine, et une ingestion excessive de sel pourrait être l'un des facteurs-clé déclenchant l'apparition d'un phénotype hypertensif. L'hormone aldosterone diminue l'excrétion de sodium par le rein en modulant l'expression de gènes qui pourraient être impliqués dans la sensibilité au sel. Dans une lignée cellulaire de rein l'expression du gène TSC22D3, qui se traduit en la protéine Glucocorticoid Induced Leucine Zipper (GILZ), est fortement induite par l'aldosterone. Ceci suggère que GILZ est un médiateur potentiel de l'effet de l'aldosterone, et pourrait être impliqué dans la sensibilité au sel. Pour analyser la fonction de GILZ dans le rein plusieurs approches ont été utilisées. Par exemple, une souris dans laquelle GILZ est spécifiquement inactivé dans le rein est en train d'être produite et permettra l'étude du rôle de GILZ dans l'organisme. De plus, on a montré que GILZ, en conditions basales, n'a pas d'effet direct sur la protéine transportant le sodium à travers la membrane des cellules, le canal sodique épithélial ENaC. On a aussi essayé de trouver des protéines qui interagissent directement avec GILZ utilisant une technique appelée du « double-hybride dans la levure », mais aucun candidat n'a émergé. Des études ont montré que, à de hautes concentrations, l'insuline peut aussi diminuer l'excrétion de sodium. A ces concentrations, elle peut activer son récepteur spécifique, mais aussi le récepteur d'une autre hormone, l'Insulin-Like Growth Factor 1 (IGF-1). En plus, l'infusion d'IGF-1 augmente la rétention rénale de sodium et d'eau, et des mutations du gène codant pour l'IGF-1 sont liées aux différents niveaux de pression sanguine. On a utilisé une nouvelle lignée cellulaire de rein développée dans notre laboratoire, appelée mCCDc11, pour analyser l'importance relative des deux hormones dans l'induction du transport de sodium. On a montré que les deux hormones induisent une augmentation significative du transport de sodium par l'activation de récepteurs à l'IGF-1 et non du récepteur à l'insuline. On a montré qu'à l'intérieur de la cellule leur activation induit une augmentation du transport sodique par le biais du canal ENaC en modifiant la quantité de phosphates fixés sur la protéine Serumand Glucocorticoid-induced Kinase 1 (Sgk1). On a finalement montré que l'IGF-1 et l'aldosterone ont un effet additif sur le transport de sodium en agissant toutes les deux sur Sgk1, qui intègre leurs effets dans le contrôle du transport de sodium dans le rein.

Regulation of human class I alcohol dehydrogenases by bile acids

Class I alcohol dehydrogenases (ADH1s) are the rate-limiting enzymes for ethanol and vitamin A (retinol) metabolism in the liver . Because previous studies have shown that human ADH1 enzymes may participate in bile acid metabolism, we investigated whether the bile acid-activated nuclear receptor farnesoid X receptor (FXR) regulates ADH1 genes. In human hepatocytes, both the endogenous FXR ligand chenodeoxycholic acid and synthetic FXR-specific agonist GW4064 increased ADH1 mRNA, protein, and activity. Moreover, overexpression of a constitutively active form of FXR induced ADH1A and ADH1B expression, whereas silencing of FXR abolished the effects of FXR agonists on ADH1 expression and activity. Transient transfection studies and electrophoretic mobility shift assays revealed functional FXR response elements in the ADH1A and ADH1B proximal promoters, thus indicating that both genes are direct targets of FXR. These findings provide the first evidence for direct connection of bile acid signaling and alcohol metabolism.

ERK1/2 controls Na,K-ATPase activity and transepithelial sodium transport in the principal cell of the cortical collecting duct of the mouse kidney.

The collecting duct of normal kidney exhibits significant activity of the MEK1/2-ERK1/2 pathway as shown in vivo by immunostaining of phosphorylated active ERK1/2 (pERK1/2). The MEK1/2-ERK1/2 pathway controls many different ion transports both in proximal and distal nephron, raising the question of whether this pathway is involved in the basal and/or hormone-dependent transepithelial sodium reabsorption in the principal cell of the cortical collecting duct (CCD), a process mediated by the apical epithelial sodium channel and the basolateral sodium pump (Na,K-ATPase). To answer this question we used ex vivo microdissected CCDs from normal mouse kidney or in vitro cultured mpkCCDcl4 principal cells. Significant basal levels of pERK1/2 were observed ex vivo and in vitro. Aldosterone and vasopressin, known to up-regulate sodium reabsorption in CCDs, did not change ERK1/2 activity either ex vivo or in vitro. Basal and aldosterone- or vasopressin-stimulated sodium transport was down-regulated by the MEK1/2 inhibitor PD98059, in parallel with a decrease in pERK1/2 in vitro. The activity of Na,K-ATPase but not that of epithelial sodium channel was inhibited by MEK1/2 inhibitors in both unstimulated and aldosterone- or vasopressin-stimulated CCDs in vitro. Cell surface biotinylation showed that intrinsic activity rather than cell surface expression of Na,K-ATPase was controlled by pERK1/2. PD98059 also significantly inhibited the activity of Na,K-ATPase ex vivo. Our data demonstrate that the ERK1/2 pathway controls Na,K-ATPase activity and transepithelial sodium transport in the principal cell and indicate that basal constitutive activity of the ERK1/2 pathway is a critical component of this control.

Transcriptome of a mouse kidney cortical collecting duct cell line: effects of aldosterone and vasopressin.

Aldosterone and vasopressin are responsible for the final adjustment of sodium and water reabsorption in the kidney. In principal cells of the kidney cortical collecting duct (CCD), the integral response to aldosterone and the long-term functional effects of vasopressin depend on transcription. In this study, we analyzed the transcriptome of a highly differentiated mouse clonal CCD principal cell line (mpkCCD(cl4)) and the changes in the transcriptome induced by aldosterone and vasopressin. Serial analysis of gene expression (SAGE) was performed on untreated cells and on cells treated with either aldosterone or vasopressin for 4 h. The transcriptomes in these three experimental conditions were determined by sequencing 169,721 transcript tags from the corresponding SAGE libraries. Limiting the analysis to tags that occurred twice or more in the data set, 14,654 different transcripts were identified, 3,642 of which do not match known mouse sequences. Statistical comparison (at P < 0.05 level) of the three SAGE libraries revealed 34 AITs (aldosterone-induced transcripts), 29 ARTs (aldosterone-repressed transcripts), 48 VITs (vasopressin-induced transcripts) and 11 VRTs (vasopressin-repressed transcripts). A selection of the differentially-expressed, hormone-specific transcripts (5 VITs, 2 AITs and 1 ART) has been validated in the mpkCCD(cl4) cell line either by Northern blot hybridization or reverse transcription-PCR. The hepatocyte nuclear transcription factor HNF-3-alpha (VIT39), the receptor activity modifying protein RAMP3 (VIT48), and the glucocorticoid-induced leucine zipper protein (GILZ) (AIT28) are candidate proteins playing a role in physiological responses of this cell line to vasopressin and aldosterone.