Collecting duct-specific knockout of endothelin-1 alters vasopressin regulation of urine osmolality

2005 ◽  
Vol 288 (5) ◽  
pp. F912-F920 ◽  
Author(s):  
Yuqiang Ge ◽  
Dowahn Ahn ◽  
Peter K. Stricklett ◽  
Alisa K. Hughes ◽  
Masashi Yanagisawa ◽  
...  
Keyword(s):  
Collecting Duct ◽  
Urine Volume ◽  
Urine Osmolality ◽  
Water Metabolism ◽  
Urinary Osmolality ◽  
Water Load ◽  
Endothelin 1 ◽  
Normal Water

In vitro studies suggest that endothelin-1 (ET-1) inhibits vasopressin (AVP)-stimulated water permeability in the collecting duct (CD). To evaluate the role of CD-derived ET-1 in regulating renal water metabolism, the ET-1 gene was selectively disrupted in the CD (CD ET-1 KO). During normal water intake, urinary osmolality (Uosm), plasma Na concentration, urine volume, and renal aquaporin-2 (AQP2) levels were unchanged, but plasma AVP concentration was reduced in CD ET-1 KO animals. CD ET-1 KO mice had impaired ability to excrete an acute, but not a chronic, water load, and this was associated with increased CD ET-1 mRNA in control, but not CD ET-1 KO, mice. In response to continuous infusion of 1-desamino-8-d-arginine vasopressin, CD ET-1 KO mice had greater increases in Uosm, V2 and AQP2 mRNA, and phosphorylation of AQP2. CD suspensions from CD ET-1 KO mice had enhanced AVP- and forskolin-stimulated cAMP accumulation. These data indicate that CD ET-1 KO increases renal sensitivity to the urinary concentrating effects of AVP and suggest that ET-1 functions as a physiological autocrine regulator of AVP action in the CD.

Role of prostaglandins in collecting duct-derived endothelin-1 regulation of blood pressure and water excretion

2007 ◽  
Vol 293 (6) ◽  
pp. F1805-F1810 ◽  
Author(s):  
Yuqiang Ge ◽  
Kevin A. Strait ◽  
Peter K. Stricklett ◽  
Tianxin Yang ◽  
Donald E. Kohan
Keyword(s):  
Blood Pressure ◽  
Collecting Duct ◽  
Urine Volume ◽  
Mrna Levels ◽  
Water Excretion ◽  
Salt Loading ◽  
Endothelin 1 ◽  
Cox 2 ◽  
Cox 1

Collecting duct (CD)-derived endothelin-1 (ET-1) exerts natriuretic, diuretic, and hypotensive effects. In vitro studies have implicated cyclooxygenase (COX) metabolites, and particularly PGE2, as important mediators of CD ET-1 effects. However, it is unknown whether PGE2 mediates CD-derived ET-1 actions in vivo. To test this, CD ET-1 knockout (KO) and control mice were studied. During normal salt and water intake, urinary PGE2 excretion was unexpectedly increased in CD ET-1 KO mice compared with controls. Salt loading markedly increased urinary PGE2 excretion in both groups of mice; however, the levels remained relatively higher in KO animals. Acutely isolated inner medullary collecting duct (IMCD) from KO mice also had increased PGE2 production. The increased IMCD PGE2 was COX-2 dependent, since NS-398 blocked all PGE2 production. However, increased CD ET-1 KO COX-2 protein or mRNA could not be detected in inner medulla or IMCD, respectively. Inner medullary COX-1 mRNA and protein levels and IMCD COX-1 mRNA levels were unaffected by Na intake or CD ET-1 KO. KO mice on a normal or high-Na diet had elevated blood pressure compared with controls; this difference was not altered by indomethacin or NS-398 treatment. However, indomethacin or NS-398 did increase urine osmolality and reduce urine volume in KO, but not control, animals. In summary, IMCD COX-2-dependent PGE2 production is increased in CD ET-1 KO mice, indicating that CD-derived ET-1 is not a primary regulator of IMCD PGE2. Furthermore, the increased PGE2 in CD ET-1 KO mice partly compensates for loss of ET-1 with respect to maintaining urinary water excretion, but not in blood pressure control.

scholarly journals Long-term aldosterone treatment induces decreased apical but increased basolateral expression of AQP2 in CCD of rat kidney

2007 ◽  
Vol 293 (1) ◽  
pp. F87-F99 ◽  
Author(s):  
Sophie de Seigneux ◽  
Jakob Nielsen ◽  
Emma T. B. Olesen ◽  
Henrik Dimke ◽  
Tae-Hwan Kwon ◽  
...  
Keyword(s):  
Collecting Duct ◽  
Rat Kidney ◽  
Urine Volume ◽  
Urine Osmolality ◽  
Sodium Reabsorption ◽  
Urinary Concentration ◽  
High Dose ◽  
Free Access ◽  
Cortical Collecting Duct ◽  
Water Metabolism

The purpose of the present studies was to determine the effects of high-dose aldosterone and dDAVP treatment on renal aquaporin-2 (AQP2) regulation and urinary concentration. Rats were treated for 6 days with either vehicle (CON; n = 8), dDAVP (0.5 ng/h, dDAVP, n = 10), aldosterone (Aldo, 150 μg/day, n = 10) or combined dDAVP and aldosterone treatment (dDAVP+Aldo, n = 10) and had free access to water with a fixed food intake. Aldosterone treatment induced hypokalemia, decreased urine osmolality, and increased the urine volume and water intake in ALDO compared with CON and dDAVP+Aldo compared with dDAVP. Immunohistochemistry and semiquantitative laser confocal microscopy revealed a distinct increase in basolateral domain AQP2 labeling in cortical collecting duct (CCD) principal cells and a reduction in apical domain labeling in Aldo compared with CON rats. Given the presence of hypokalemia in aldosterone-treated rats, we studied dietary-induced hypokalemia in rats, which also reduced apical AQP2 expression in the CCD but did not induce any increase in basolateral AQP2 expression in the CCD as observed with aldosterone treatment. The aldosterone-induced basolateral AQP2 expression in the CCD was thus independent of hypokalemia but was dependent on the presence of sodium and aldosterone. This redistribution was clearly blocked by mineralocorticoid receptor blockade. The increased basolateral expression of AQP2 induced by aldosterone may play a significant role in water metabolism in conditions with increased sodium reabsorption in the CCD.

scholarly journals Collecting duct-specific knockout of adenylyl cyclase type VI causes a urinary concentration defect in mice

2012 ◽  
Vol 302 (1) ◽  
pp. F78-F84 ◽  
Author(s):  
Karl P. Roos ◽  
Kevin A. Strait ◽  
Kalani L. Raphael ◽  
Mitsi A. Blount ◽  
Donald E. Kohan
Keyword(s):  
Adenylyl Cyclase ◽  
Water Intake ◽  
Arginine Vasopressin ◽  
Water Deprivation ◽  
Collecting Duct ◽  
Urine Volume ◽  
Urine Osmolality ◽  
Camp Accumulation ◽  
Water Excretion ◽  
Normal Water

Collecting duct (CD) adenylyl cyclase VI (AC6) has been implicated in arginine vasopressin (AVP)-stimulated renal water reabsorption. To evaluate the role of CD-derived AC6 in regulating water homeostasis, mice were generated with CD-specific knockout (KO) of AC6 using the Cre/loxP system. CD AC6 KO and controls were studied under normal water intake, chronically water loaded, or water deprived; all of these conditions were repeated in the presence of continuous administration of 1-desamino-8-d-arginine vasopressin (DDAVP). During normal water intake or after water deprivation, urine osmolality (Uosm) was reduced in CD AC6 KO animals vs. controls. Similarly, Uosm was decreased in CD AC6 KO mice vs. controls after water deprivation+DDAVP administration. Pair-fed (with controls) CD AC6 KO mice also had lower urine osmolality vs. controls. There were no detectable differences between KO and control animals in fluid intake or urine volume under any conditions. CD AC6 KO mice did not have altered plasma AVP levels vs. controls. AVP-stimulated cAMP accumulation was reduced in acutely isolated inner medullary CD (IMCD) from CD A6 KO vs. controls. Medullary aquaporin-2 (AQP2) protein expression was lower in CD AC6 KO mice vs. controls. There were no differences in urinary urea excretion or IMCD UT-A1 expression; however, IMCD UT-A3 expression was reduced in CD AC6 KO mice vs. controls. In summary, AC6 in the CD regulates renal water excretion, most likely through control of AVP-stimulated cAMP accumulation and AQP2.

scholarly journals Kidney-specific WNK1 inhibits sodium reabsorption in the cortical thick ascending limb

2012 ◽  
Vol 303 (5) ◽  
pp. F667-F673 ◽  
Author(s):  
Chih-Jen Cheng ◽  
Thao Truong ◽  
Michel Baum ◽  
Chou-Long Huang
Keyword(s):  
Collecting Duct ◽  
Urine Volume ◽  
Sodium Reabsorption ◽  
Renal Tubules ◽  
Thick Ascending Limb ◽  
Cortical Collecting Duct ◽  
Wild Type ◽  
High K

Kidney-specific WNK1 (KS-WNK1) is a variant of full-length WNK1. Previous studies have reported that KS-WNK1 is predominantly expressed in the distal convoluted tubule (DCT) where it regulates sodium-chloride cotransporter. The role of KS-WNK1 in other nephron segments is less clear. Here, we measured the expression of KS-WNK1 transcript in microdissected renal tubules and found that KS-WNK1 was most abundant in the DCT, followed by cortical thick ascending limb (cTAL), connecting tubule, and cortical collecting duct. A high K+ diet enhanced the expression of KS-WNK1 in the DCT and cTAL, selectively. It has been reported that a high-K diet suppresses Na+ reabsorption in TAL. To understand the role of KS-WNK1 in Na+ transport in cTAL and the regulation by dietary K+, we examined Na+ reabsorption using in vitro microperfusion in cTAL isolated from KS-WNK1-knockout mice and wild-type littermates fed either a control-K+ or high-K+ diet. Furosemide-sensitive Na+ reabsorption in cTAL was higher in KS-WNK1-knockout (KO) mice than in wild-type. A high-K+ diet inhibited Na+ reabsorption in cTAL from wild-type mice, but the inhibition was eliminated in KS-WNK1-KO mice. We further examined the role of KS-WNK1 using transgenic mice that overexpress KS-WNK1. Na+ reabsorption in cTAL was lower in transgenic than in wild-type mice. In whole animal clearance studies, a high-K+ diet increased daily urine volume and urinary Na+ and K+ excretion in wild-type mice, which was blunted in KS-WNK1-KO mice. Thus KS-WNK1 inhibits Na+ reabsorption in cTAL and mediates the inhibition of Na+ reabsorption in the segment by a high-K diet.

Nonosmotic release of vasopressin and renal aquaporins in impaired urinary dilution in hypothyroidism

2005 ◽  
Vol 289 (4) ◽  
pp. F672-F678 ◽  
Author(s):  
Yung-Chang Chen ◽  
Melissa A. Cadnapaphornchai ◽  
Jianhui Yang ◽  
Sandra N. Summer ◽  
Sandor Falk ◽  
...  
Keyword(s):  
Protein Expression ◽  
Renal Cortex ◽  
Free Water ◽  
Urine Osmolality ◽  
Protein Abundance ◽  
Oral Gavage ◽  
Water Excretion ◽  
Urinary Osmolality ◽  
Water Load ◽  
Fluid Delivery

The purpose of this study was to examine protein expression of renal aquaporins (AQP) and ion transporters in hypothyroid (HT) rats in response to an oral water load compared with controls (CTL) and HT rats replaced with l-thyroxine (HT+T). Hypothyroidism was induced by aminotriazole administration for 10 wk. Body weight, water intake, urine output, solute and urea excretion, and serum and urine osmolality were comparable among the three groups at the conclusion of the 10-wk treatment period. One hour after oral gavage of water (50 ml/kg body wt), HT rats demonstrated significantly less water excretion, higher minimal urinary osmolality, and decreased serum osmolality compared with CTL and HT+T rats. Despite the hyposmolality, plasma vasopressin concentration was elevated in HT rats. These findings in HT rats were associated with an increase in protein abundance of renal cortex AQP1 and inner medulla AQP2. AQP3, AQP4, and the Na-K-2Cl cotransporter were also increased. Moreover, 1 h following the oral water load, HT rats demonstrated a significant increase in the membrane-to-vesicle fraction of AQP2 by Western blot analysis. The defect in urinary dilution in HT rats was reversed by the V2 vasopressin antagonist OPC-31260. In conclusion, impaired urinary dilution in HT rats is primarily compatible with the nonosmotic release of vasopressin and increased protein expression of renal AQP2. The impairment of maximal solute-free water excretion in HT rats, however, appears also to involve diminished distal fluid delivery.

Abstract 103: Soluble (Pro)Renin Receptor Targets Renal V2 Vasopressin Receptor to Enhance Urine Concentrating Capability

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Fei Wang ◽  
Nirupama Ramkumar ◽  
Kexin Peng ◽  
Xiaohan Lu ◽  
Long Zhao ◽  
...  
Keyword(s):  
Biological Fluid ◽  
Collecting Duct ◽  
Urine Volume ◽  
Neutralizing Antibody ◽  
Fold Increase ◽  
Medium Level ◽  
V2 Vasopressin Receptor ◽  
Receptor Targets ◽  
Renal Expression

The extracellular domain of (pro)renin receptor (PRR) is cleaved to produce a 28 kDa soluble receptor (sPRR) which is detected in biological fluid and elevated under certain pathological conditions. Our recent work suggests that sPRR derived from collecting duct intercalated cells acts in a paracrine fashion to regulate water transport in the principal cells. The present study attempted to further define the role of sPRR in vasopressin (AVP) signaling with emphasis on V2R regulation. In primary rat IMCD cells, treatment with a recombinant sPRR termed as sPRR-His at 10 nM for 12 h induced a 2.8 -fold increase in V2R protein and a 2-fold increase in V2R mRNA. Following AVP treatment, V2R protein expression was increased by 3-fold, which was blunted by a PRR antagonist (PRO20) and a PRR neutralizing antibody. Mice with CD-specific (CD PRR KO) developed a medium level of diabetes insipidus (urine volume: KO: 2.2±0.4 versus Floxed: 1.2±0.3 ml/day; P <0.05), accompanied with a 60% reduction of renal V2R protein and a 25% reduction of urinary sPRR excretion. Adminstration of sPRR-His at for 3 d almost completely rescued the polyuria phenotype of CD PRR KO mice (urine volume: KO+sPRR-His: 1.6±0.3 vs. KO: 2.4±0.5 ml/day, p <0.05) associated with restoration of renal V2R protein and AQP2 protein abundances. Interestingly, nephron-specific PRR KO (Neph PRR KO) exhibited more robust polyuria (urine volume: KO: 7.3±1.1 vs. Floxed: 1.2±0.5 ml/day, p <0.01) associated with suppressed renal expression of AQP2, NKCC2, and V2R. Administration of sPRR-His to Neph PRR KO mice partially attenuated polyuria (urine volume: KO+sPRR-His: 4.1±1.2 vs. KO: 7.3±1.1 ml/day, p <0.01) accompanied by restored renal expression of V2R and AQP2, as well as AVP sensitivity. In contrast, the downregulation of NKCC2 expression in the null mice was unaffected by sPRR-His infusion nor was the upregulation of autophagosome marker microtubule-associated protein 1A/1B-light chain 3 (LC3b). Together, our data suggests that sPRR selectively targets the CD to determine V2R expression and hence AVP sensitivity and urine concentrating capability, independently of autophagosome accumulation.

scholarly journals Endothelial ERK1/2 signaling maintains integrity of the quiescent endothelium

2019 ◽  
Vol 216 (8) ◽  
pp. 1874-1890 ◽  
Author(s):  
Nicolas Ricard ◽  
Rizaldy P. Scott ◽  
Carmen J. Booth ◽  
Heino Velazquez ◽  
Nicholas A. Cilfone ◽  
...  
Keyword(s):  
Rapid Onset ◽  
Cardiac Conduction ◽  
Tgfβ Signaling ◽  
Mesenchymal Transition ◽  
Endothelin 1 ◽  
Endocrine Organs ◽  
Endothelial To Mesenchymal Transition

To define the role of ERK1/2 signaling in the quiescent endothelium, we induced endothelial Erk2 knockout in adult Erk1−/− mice. This resulted in a rapid onset of hypertension, a decrease in eNOS expression, and an increase in endothelin-1 plasma levels, with all mice dying within 5 wk. Immunostaining and endothelial fate mapping showed a robust increase in TGFβ signaling leading to widespread endothelial-to-mesenchymal transition (EndMT). Fibrosis affecting the cardiac conduction system was responsible for the universal lethality in these mice. Other findings included renal endotheliosis, loss of fenestrated endothelia in endocrine organs, and hemorrhages. An ensemble computational intelligence strategy, comprising deep learning and probabilistic programing of RNA-seq data, causally linked the loss of ERK1/2 in HUVECs in vitro to activation of TGFβ signaling, EndMT, suppression of eNOS, and induction of endothelin-1 expression. All in silico predictions were verified in vitro and in vivo. In summary, these data establish the key role played by ERK1/2 signaling in the maintenance of vascular normalcy.

Prevention of two-kidney, one-clip renal hypertension in rat by ablation of AV3V tissue

1983 ◽  
Vol 245 (4) ◽  
pp. H683-H689 ◽  
Author(s):  
J. R. Haywood ◽  
G. D. Fink ◽  
J. Buggy ◽  
S. Boutelle ◽  
A. K. Johnson ◽  
...  
Keyword(s):  
Renal Artery ◽  
Third Ventricle ◽  
Renal Hypertension ◽  
Urine Volume ◽  
Urine Osmolality ◽  
Sham Operation ◽  
Vasopressin Release ◽  
Transient Rise ◽  
Fluid Regulation

This study examined the role of the anteroventral third ventricle (AV3V) in the renin-dependent two-kidney, one-clip model of renal hypertension. AV3V lesion and sham lesion rats were subjected to the placement of a clip on one renal artery or a sham operation. The sham lesion-renal artery clip rats experienced an increase in systolic blood pressure; however, AV3V lesioned animals experienced only a transient rise in arterial pressure during the 1st wk after clip. Body fluid regulation studies during the course of the hypertension revealed that there were no differences in water intake and urine volume between the lesion- and sham lesion-renal artery clip animals. Although significantly greater plasma and blood volumes were demonstrated in the AV3V lesion-sham clip rats compared with sham lesion animals, no differences in vascular volumes were detected in the renal artery clip rats. Finally, the rats were water deprived for 3 days to maximally stimulate vasopressin release. Urine osmolality increased significantly in all groups of rats except the AV3V lesion-renal artery clip animals protected against the hypertension.

scholarly journals The Deubiquitylase USP4 Interacts with the Water Channel AQP2 to Modulate Its Apical Membrane Accumulation and Cellular Abundance

Cells ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 265 ◽  
Author(s):  
Sathish Murali ◽  
Takwa Aroankins ◽  
Hanne Moeller ◽  
Robert Fenton
Keyword(s):  
Collecting Duct ◽  
Water Channel ◽  
Mouse Kidney ◽  
Body Water ◽  
Mrna Levels ◽  
E3 Ligases ◽  
Water Homeostasis ◽  
And Function

Aquaporin 2 (AQP2) mediates the osmotic water permeability of the kidney collecting duct in response to arginine vasopressin (VP) and is essential for body water homeostasis. VP effects on AQP2 occur via long-term alterations in AQP2 abundance and short-term changes in AQP2 localization. Several of the effects of VP on AQP2 are dependent on AQP2 phosphorylation and ubiquitylation; post-translational modifications (PTM) that modulate AQP2 subcellular distribution and function. Although several protein kinases, phosphatases, and ubiquitin E3 ligases have been implicated in AQP2 PTM, how AQP2 is deubiquitylated or the role of deubiquitylases (DUBS) in AQP2 function is unknown. Here, we report a novel role of the ubiquitin-specific protease USP4 in modulating AQP2 function. USP4 co-localized with AQP2 in the mouse kidney, and in mpkCCD14 cells USP4 and AQP2 abundance are increased by VP. AQP2 and USP4 co-immunoprecipitated from mpkCCD14 cells and mouse kidney, and in vitro, USP4 can deubiquitylate AQP2. In mpkCCD14 cells, shRNA mediated knockdown of USP4 decreased AQP2 protein abundance, whereas no changes in AQP2 mRNA levels or VP-induced cAMP production were detected. VP-induced AQP2 membrane accumulation in knockdown cells was significantly reduced, which was associated with higher levels of ubiquitylated AQP2. AQP2 protein half-life was also significantly reduced in USP4 knockdown cells. Taken together, the data suggest that USP4 is a key regulator of AQP2 deubiquitylation and that loss of USP4 leads to increased AQP2 ubiquitylation, decreased AQP2 levels, and decreased cell surface AQP2 accumulation upon VP treatment. These studies have implications for understanding body water homeostasis.

Autocrine role of endothelin in rat IMCD: inhibition of AVP-induced cAMP accumulation

1993 ◽  
Vol 265 (1) ◽  
pp. F126-F129 ◽  
Author(s):  
D. E. Kohan ◽  
A. K. Hughes
Keyword(s):  
Arginine Vasopressin ◽  
Collecting Duct ◽  
Camp Accumulation ◽  
Semipermeable Membranes ◽  
Endothelin 1 ◽  
Cyclic Monophosphate ◽  
Nephron Segment ◽  
Specific Receptors ◽  
Medullary Collecting Duct

Exogenous endothelin-1 (ET-1) inhibits arginine vasopressin (AVP)-induced adenosine 3',5'-cyclic monophosphate (cAMP) accumulation in the inner medullary collecting duct (IMCD). Since ET-1 is produced by, and binds to specific receptors on, the IMCD, the possibility exists that ET-1 is an autocrine regulator of AVP action in this nephron segment. To test this hypothesis, rat IMCD cells grown on semipermeable membranes were exposed to rabbit anti-ET antisera or nonimmune rabbit sera (NRS). AVP (10(-9)M) caused a significantly greater accumulation of cAMP in confluent IMCD monolayers preincubated in ET-1 antisera compared with NRS. ET-1 (10(-8) M) inhibited the AVP-induced rise in cAMP by 65% in cells preincubated in ET-1 antisera, but had no effect in NRS-treated cells. Finally, 125I-ET-1 (30 pM) binding was increased sixfold in IMCD preincubated in anti-ET-1 antisera. These data indicate that ET causes tonic autocrine inhibition of AVP responsiveness in the IMCD.

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