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Ellison DH. Treatment of Disorders of Sodium Balance in Chronic Kidney Disease. Adv Chronic Kidney Dis 2017; 24:332-341. [PMID: 29031361 DOI: 10.1053/j.ackd.2017.07.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 07/25/2017] [Indexed: 12/23/2022]
Abstract
Extracellular fluid volume expansion is nearly universal in patients with CKD. Such volume expansion has features similar to the syndrome of heart failure with preserved ejection fraction, which not only leads to symptoms but can also lead to further organ damage. Unique treatment challenges are present in this patient population, including low glomerular filtration, which limits sodium chloride filtration, intrinsic tubule predisposition to sodium chloride retention, and proteinuria. In addition, pharmacokinetic considerations alter the disposition of diuretics in patients with CKD and nephrotic syndrome. Maintaining extracellular fluid volume near to normal is often necessary for hypertension treatment in this population, but it may also help prevent progressive cardiovascular and kidney damage. Although powerful diuretics can often accomplish this goal, this often comes at a cost of competing adverse effects. An approach to reduce extracellular fluid volume while avoiding adverse effects, therefore, requires a nuanced yet aggressive therapeutic approach.
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Effect of Poria cocos on Puromycin Aminonucleoside-Induced Nephrotic Syndrome in Rats. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2014; 2014:570420. [PMID: 25165480 PMCID: PMC4140122 DOI: 10.1155/2014/570420] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 07/08/2014] [Accepted: 07/13/2014] [Indexed: 01/26/2023]
Abstract
Nephrotic syndrome is associated with altered renal handling of water and sodium and changes in the levels of aquaporins (AQPs) and epithelial Na channels (ENaCs). The dried sclerotia of Poria cocos Wolf (WPC) have been used for treating chronic edema and nephrosis. We evaluated the effects of WPC on puromycin aminonucleoside- (PAN-) induced renal functional derangement and altered renal AQP2 and ENaC expression. In the nephrotic syndrome rat model, animals were injected with 75 mg/kg PAN and then treated with Losartan (30 mg·kg−1·day−1) or WPC (200 mg·kg−1·day−1) for 7 days. In the WPC group, proteinuria and ascites improved significantly. Plasma levels of triglyceride, total cholesterol, and low-density lipoprotein- (LDL-) cholesterol reduced significantly in the WPC group. In addition, the WPC group exhibited attenuation of the PAN-induced increase in AQP2 and ENaC α/β subunit protein and mRNA levels. WPC suppressed significantly PAN-induced organic osmolyte regulators, reducing serum- and glucocorticoid-inducible protein kinase (Sgk1) and sodium-myo-inositol cotransporter (SMIT) mRNA expression. Our results show that WPC improves nephrotic syndrome, including proteinuria and ascites, through inhibition of AQP2 and ENaC expression. Therefore, WPC influences body-fluid regulation via inhibition of water and sodium channels, thereby, improving renal disorders such as edema or nephrosis.
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Svenningsen P, Skøtt O, Jensen BL. Proteinuric diseases with sodium retention: is plasmin the link? Clin Exp Pharmacol Physiol 2011; 39:117-24. [DOI: 10.1111/j.1440-1681.2011.05524.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
Pioneering investigations conducted over a half century ago on tonicity, transcapillary fluid exchange, and the distribution of water and solute serve as a foundation for understanding the physiology of body fluid spaces. With passage of time, however, some of these concepts have lost their connectivity to more contemporary information. Here we examine the physical forces determining the compartmentalization of body fluid and its movement across capillary and cell membrane barriers, drawing particular attention to the interstitium operating as a dynamic interface for water and solute distribution rather than as a static reservoir. Newer work now supports an evolving model of body fluid dynamics that integrates exchangeable Na(+) stores and transcapillary dynamics with advances in interstitial matrix biology.
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Affiliation(s)
- Gautam Bhave
- Division of Nephrology and Hypertension, Department of Medicine, S3223 Medical Center North, Vanderbilt University School of Medicine, Nashville, TN 37232-2372, USA.
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Abstract
Glomerulonephritis is characterized by hematuria, proteinuria, hypertension, and edema, but the mechanisms contributing to volume disorders are controversial. Here we used the rat anti-Thy1 model of mesangioproliferative glomerulonephritis to test the hypothesis that disturbed salt and water homeostasis is based on tubular epithelial changes that cause salt retention. In this model there was an early onset of pronounced proteinuria and lipiduria associated with reduced fractional sodium excretion and a lowering of the renin-angiotensin-aldosterone system. The glomerular filtration rate and creatinine clearance were decreased on day 6. There was a reduced abundance of the major salt and water transport proteins on the proximal tubular brush border membrane and which paralleled cellular protein overload, enhanced membrane cholesterol uptake and cytoskeletal changes. Alterations in thick ascending limb were moderate. Changes in the collecting ducts were characterized by an enhanced abundance and increased subunit cleavage of the epithelial sodium channel, both events consistent with increased sodium reabsorption. We suggest that irrespective of the proximal tubular changes, altered collecting duct sodium reabsorption may be crucial for volume retention in acute glomerulonephritis. We suggest that enhanced proteolytic cleavage of ion transporter subunits might be a novel mechanism of channel activation in glomerular diseases. Whether these proteases are filtered or locally secreted awaits determination.
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Kastner C, Pohl M, Sendeski M, Stange G, Wagner CA, Jensen B, Patzak A, Bachmann S, Theilig F. Effects of receptor-mediated endocytosis and tubular protein composition on volume retention in experimental glomerulonephritis. Am J Physiol Renal Physiol 2009; 296:F902-11. [PMID: 19193726 DOI: 10.1152/ajprenal.90451.2008] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Human glomerulonephritis (GN) is characterized by sustained proteinuria, sodium retention, hypertension, and edema formation. Increasing quantities of filtered protein enter the renal tubule, where they may alter epithelial transport functions. Exaggerated endocytosis and consequent protein overload may affect proximal tubules, but intrinsic malfunction of distal epithelia has also been reported. A straightforward assignment to a particular tubule segment causing salt retention in GN is still controversial. We hypothesized that 1) trafficking and surface expression of major transporters and channels involved in volume regulation were altered in GN, and 2) proximal tubular endocytosis may influence locally as well as downstream expressed tubular transporters and channels. Effects of anti-glomerular basement membrane GN were studied in controls and megalin-deficient mice with blunted proximal endocytosis. Mice displayed salt retention and elevated systolic blood pressure when proteinuria had reached 10-15 mg/24 h. Surface expression of proximal Na(+)-coupled transporters and water channels was in part [Na(+)-P(i) cotransporter IIa (NaPi-IIa) and aquaporin-1 (AQP1)] increased by megalin deficiency alone, but unchanged (Na(+)/H(+) exchanger 3) or reduced (NaPi-IIa and AQP1) in GN irrespective of the endocytosis defect. In distal epithelia, significant increases in proteolytic cleavage products of alpha-epithelial Na(+) channel (ENaC) and gamma-ENaC were observed, suggesting enhanced tubular sodium reabsorption. The effects of glomerular proteinuria dominated over those of blunted proximal endocytosis in contributing to ENaC cleavage. Our data indicate that ENaC-mediated sodium entry may be the rate-limiting step in proteinuric sodium retention. Enhanced proteolytic cleavage of ENaC points to a novel mechanism of channel activation which may involve the action of filtered plasma proteases.
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Affiliation(s)
- Christian Kastner
- Charité-Universitätsmedizin Berlin, Institut für Vegetative Anatomie, Philippstr. 12, 10115 Berlin, Germany
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Morgan TK, Montgomery K, Mason V, West RB, Wang L, van de Rijn M, Higgins JP. Upregulation of histidine decarboxylase expression in superficial cortical nephrons during pregnancy in mice and women. Kidney Int 2006; 70:306-14. [PMID: 16760908 DOI: 10.1038/sj.ki.5001553] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mechanisms regulating pregnancy-induced changes in renal function are incompletely understood. Few candidate genes have been identified and data suggest that alternate mechanisms remain to be elucidated. Our objective was to screen thousands of genes expressed in kidneys from mice throughout gestation to identify possible key regulators of renal function during pregnancy. Mouse complementary DNA microarrays were used to screen for differences in expression during pregnancy in C57BL/6 mice. Interesting candidate genes whose expression varied with pregnancy were further analyzed by reverse transcription-PCR and Northern blot. Expression was localized by in situ hybridization and immunohistochemistry. Follow-up immunohistochemical analyses in archival human kidney sections from the fetus, non-pregnant, and pregnant women were also performed. Histidine decarboxylase (HDC), the enzyme that synthesizes histamine, was markedly upregulated in the mouse kidney during pregnancy. HDC expression localized to proximal tubule cells of fetal and adult mice. Females showed strong expression in the juxtamedullary zone before pregnancy and upregulation in the superficial cortical zone (SCZ) by mid-gestation. Histamine colocalized with HDC. Male mice showed only low HDC expression. Similar expression patterns were observed in human kidneys. Our results show that HDC expression and histamine production are increased in the SCZ during pregnancy. If histamine acts as a vasodilator, we speculate that increasing production in the SCZ may increase renal blood flow to this zone and recruit superficial cortical nephrons during pregnancy.
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Affiliation(s)
- T K Morgan
- Department of Pathology, Stanford University Medical Center, Stanford, California, USA.
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Kim SW, Wang W, Nielsen J, Praetorius J, Kwon TH, Knepper MA, Frøkiaer J, Nielsen S. Increased expression and apical targeting of renal ENaC subunits in puromycin aminonucleoside-induced nephrotic syndrome in rats. Am J Physiol Renal Physiol 2004; 286:F922-35. [PMID: 15075188 DOI: 10.1152/ajprenal.00277.2003] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Nephrotic syndrome is often accompanied by sodium retention and generalized edema. However, the molecular basis for the decreased renal sodium excretion remains undefined. We hypothesized that epithelial Na channel (ENaC) subunit dysregulation may be responsible for the increased sodium retention. An experimental group of rats was treated with puromycin aminonucleoside (PAN; 180 mg/kg iv), whereas the control group received only vehicle. After 7 days, PAN treatment induced significant proteinuria, hypoalbuminemia, decreased urinary sodium excretion, and extensive ascites. The protein abundance of α-ENaC and β-ENaC was increased in the inner stripe of the outer medulla (ISOM) and in the inner medulla (IM) but was not altered in the cortex. γ-ENaC abundance was increased in the cortex, ISOM, and IM. Immunoperoxidase brightfield- and laser-scanning confocal fluorescence microscopy demonstrated increased targeting of α-ENaC, β-ENaC, and γ-ENaC subunits to the apical plasma membrane in the distal convoluted tubule (DCT2), connecting tubule, and cortical and medullary collecting duct segments. Immunoelectron microscopy further revealed an increased labeling of α-ENaC in the apical plasma membrane of cortical collecting duct principal cells of PAN-treated rats, indicating enhanced apical targeting of α-ENaC subunits. In contrast, the protein abundances of Na+/H+exchanger type 3 (NHE3), Na+-K+-2Cl-cotransporter (BSC-1), and thiazide-sensitive Na+-Cl-cotransporter (TSC) were decreased. Moreover, the abundance of the α1-subunit of the Na-K-ATPase was decreased in the cortex and ISOM, but it remained unchanged in the IM. In conclusion, the increased or sustained expression of ENaC subunits combined with increased apical targeting in the DCT2, connecting tubule, and collecting duct are likely to play a role in the sodium retention associated with PAN-induced nephrotic syndrome. The decreased abundance of NHE3, BSC-1, TSC, and Na-K-ATPase may play a compensatory role to promote sodium excretion.
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Affiliation(s)
- Soo Wan Kim
- The Water and Salt Research Center, University of Aarhus, DK-8000 Aarhus C, Denmark
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Besse-Eschmann V, Klisic J, Nief V, Le Hir M, Kaissling B, Ambühl PM. Regulation of the proximal tubular sodium/proton exchanger NHE3 in rats with puromycin aminonucleoside (PAN)-induced nephrotic syndrome. J Am Soc Nephrol 2002; 13:2199-206. [PMID: 12191963 DOI: 10.1097/01.asn.0000028839.52271.df] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Excessive proteinuria due to loss of glomerular permselectivity in nephrotic syndrome can cause disturbances in renal salt and water handling with edema formation. Apart from oncotic and hydrostatic mechanisms associated with hypoalbuminemia, primary derangements in renal tubular sodium transport may contribute to the pathogenesis of nephrotic edema. Whereas there is evidence for an increase of cortical collecting duct sodium reabsorption in nephrotic rats, it remains controversial whether proximal tubule sodium transport may also be activated in this condition. The regulation of the cortical Na/H exchanger NHE3, the main pathway for Na reabsorption in the proximal tubule (PT), was investigated in rats with puromycin aminonucleoside (PAN)-induced nephrotic syndrome. PAN rats developed reduced GFR, severe proteinuria, and sodium retention within 3 d. After 10 d, immunoblots of brush border vesicles revealed a decreased abundance of NHE3 in nephrotic animals. However, the Na/H antiporter activity in the same vesicle preparations was not significantly altered. Antiporter activity normalized for NHE3 protein was increased by 88% in nephrotic animals (P = 0.025). Immunohistochemistry with the same polyclonal antibody as for immunoblots revealed a decrease of NHE3 abundance in PT. In contrast, immunoreactivity for the monoclonal antibody 2B9, which specifically recognizes the non-megalin-associated, transport-competent pool of NHE3, was higher in PAN-treated rats than in controls. In conclusion, increased sodium reabsorption might be associated with a shift of NHE3 from an inactive pool to an active pool, thus contributing to sodium retention in a state of proteinuria.
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Affiliation(s)
- Luis I Juncos
- IPEM-Gambro Healthcare, IV Departmnent of Medicine, National University of Cordoba, Colon 4154, Cordoba 5003, Argentina.
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Deschênes G, Gonin S, Zolty E, Cheval L, Rousselot M, Martin PY, Verbavatz JM, Féraille E, Doucet A. Increased synthesis and avp unresponsiveness of Na,K-ATPase in collecting duct from nephrotic rats. J Am Soc Nephrol 2001; 12:2241-2252. [PMID: 11675400 DOI: 10.1681/asn.v12112241] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
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.
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Affiliation(s)
- Georges Deschênes
- 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
| | - Sandrine Gonin
- Fondation pour Recherches Médicales, Laboratoire de Néphrologie, Geneva, Switzerland
| | - Einath Zolty
- Fondation pour Recherches Médicales, Laboratoire de Néphrologie, Geneva, Switzerland
| | - Lydie Cheval
- Laboratoire de Biologie Intégrée des Cellules Rénales, Service de Biologie Cellulaire, Commissariat à l'Energie Atomique, Gif sur Yvette, France
| | - Martine Rousselot
- Fondation pour Recherches Médicales, Laboratoire de Néphrologie, Geneva, Switzerland
| | - Pierre-Yves Martin
- Fondation pour Recherches Médicales, Laboratoire de Néphrologie, Geneva, Switzerland
| | - Jean-Marc Verbavatz
- Service de Biologie Cellulaire, Commissariat à l'Energie Atomique, Gif sur Yvette, France
| | - Eric Féraille
- Fondation pour Recherches Médicales, Laboratoire de Néphrologie, Geneva, Switzerland
| | - Alain Doucet
- Laboratoire de Biologie Intégrée des Cellules Rénales, Service de Biologie Cellulaire, Commissariat à l'Energie Atomique, Gif sur Yvette, France
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Deschênes G, Doucet A. Collecting duct (Na+/K+)-ATPase activity is correlated with urinary sodium excretion in rat nephrotic syndromes. J Am Soc Nephrol 2000; 11:604-615. [PMID: 10752519 DOI: 10.1681/asn.v114604] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
In puromycin aminonucleoside (PAN)-treated nephrotic rats, sodium retention is associated with increased (Na+/K+)-ATPase activity in the cortical collecting ducts (CCD). This study was undertaken to determine whether stimulation of (Na+/K+)-ATPase in the CCD is a feature of other experimental nephrotic syndromes, whether it might be responsible for renal sodium retention, and whether it is mediated by increased plasma vasopressin levels or activation of calcineurin. For this purpose, the time courses of urinary excretion of sodium and protein, sodium balance, ascites, and (Na+/K+)-ATPase activities in microdissected CCD were studied in rats with PAN or adriamycin nephrosis or HgCl2 nephropathy. The roles of vasopressin and calcineurin in PAN nephrosis were evaluated by measuring these parameters in Brattleboro rats and in rats treated with cyclosporin or tacrolimus. Despite different patterns of changes in urinary sodium and protein excretion in the three nephrotic syndrome models, there was a linear relationship between CCD (Na+/K+)-ATPase activities and sodium excretion in all three cases. The results also indicated that there was no correlation between proteinuria and sodium retention, but ascites was present only when proteinuria was associated with marked reduction of sodium excretion. Finally, the lack of vasopressin in Brattleboro rats or the inhibition of calcineurin by administration of either cyclosporin or tacrolimus did not prevent development of the nephrotic syndrome in PAN-treated rats or stimulation of CCD (Na+/K+)-ATPase. It is concluded that stimulation of Na(+/K+)-ATPase in the CCD of nephrotic rats might be responsible for sodium retention and that this phenomenon is independent of proteinuria and vasopressin and calcineurin activities.
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Affiliation(s)
- Georges Deschênes
- Service de Néphrologie Pédiatrique, Hôpital Armand-Trousseau, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Alain Doucet
- Laboratoire de Biologie Intégrée des Cellules Rénales, Centre National de la Recherche Scientifique Unité de Recherche Associée 1859, Service de Biologie Cellulaire, Commissariat à l'Energie Atomique, Saclay, France
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Abstract
Generalized edema results from alterations in renal sodium homeostasis that ultimately result in an expansion of extracellular fluid volume and accumulation of interstitial fluid. The common edematous disorders include congestive heart failure, cirrhosis, nephrotic syndrome, and renal insufficiency. The abnormalities of sodium homeostasis contributing to edema formation in each condition are discussed. Management of volume homeostasis, with an emphasis on the role of diuretic therapy, is reviewed.
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Affiliation(s)
- A Rasool
- Department of Medicine, University of Pittsburgh School of Medicine, Pennsylvania, USA
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Valentin JP, Ying WZ, Couser WG, Humphreys MH. Extrarenal resistance to atrial natriuretic peptide in rats with experimental nephrotic syndrome. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:F556-63. [PMID: 9530272 DOI: 10.1152/ajprenal.1998.274.3.f556] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Nephrotic syndrome is associated with resistance to the renal actions of atrial natriuretic peptide (ANP). We performed experiments in anesthetized, acutely nephrectomized rats 21-28 days after injection of adriamycin (7-8 mg/kg i.v.) or 9-14 days after injection of anti-Fx1A antiserum (5 ml/kg i.p.) (passive Heymann nephritis; PHN) to test whether extrarenal resistance also occurred. Proteinuria was significantly elevated in both models compared with controls before study. ANP infusion (1 microgram.kg-1.min-1) caused arterial pressure to decrease similarly in control rats, adriamycin-treated rats, and rats with PHN (by 8.2 +/- 1.0, 9.4 +/- 2.3, and 9.0 +/- 2.0%, respectively; all P < 0.05 vs. both baseline and vehicle-infused control rats). In control rats, hematocrit increased progressively to a maximal value 9.5 +/- 0.9% over baseline as a result of the infusion, an increase corresponding to a reduction in plasma volume of 16.1 +/- 0.9%. The ANP-induced increase in hematocrit was preserved in adriamycin-treated rats (9.2 +/- 1.3%) but was markedly blunted in rats with PHN (2.4 +/- 1.3%; P < 0.0001 vs. ANP infusion in control rats). ANP infusion increased plasma ANP levels to the same extent in the three groups, whereas plasma guanosine 3',5'-cyclic monophosphate was significantly lower in rats with PHN compared with both control and adriamycin-treated rats. Infusion of a subpressor dose of angiotensin II (ANG II, 2.5 ng.kg-1.min-1) fully restored the ANP-induced increase in hematocrit in rats with PHN. This study demonstrates that 1) the hemoconcentrating and hypotensive actions of ANP are preserved in adriamycin-treated rats, 2) the effect of ANP on hematocrit and fluid distribution is blunted in rats with PHN while its hypotensive action is preserved, and 3) low-level ANG II infusion normalizes the hemoconcentrating effect of exogenously infused ANP in rats with PHN. Thus deficient ANG II generation in rats with PHN, but not adriamycin nephrosis, may contribute to extrarenal ANP resistance.
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Affiliation(s)
- J P Valentin
- Division of Nephrology, San Francisco General Hospital, University of California San Francisco 94143, USA
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Abstract
Diuretic therapy in edematous diseases often yields an inadequate natriuretic response ("diuretic resistance"). To study the functional changes in patients with congestive heart failure, liver cirrhosis with ascites, and nephrotic syndrome, characterized by a reduced effective arterial blood volume (EABV), different diuretic strategies were studied. It was shown that monotherapy with hydrochlorothiazide or furosemide was followed by an inadequate natriuretic response. Correlation of diuretic response with pretreatment fractional sodium excretion of the patient revealed a clear-cut interdependency: Those patients were resistant whose FENa+ was greatly below normal (<0.2%). In addition, it was found that the coadministration of the carboanhydrase inhibitor acetazolamide to diuretic therapy was very effective. We therefore conclude that an increase in proximal-tubular Na+ reabsorption is the major ("pharmacodynamic") determinant for diuretic resistance in edematous diseases with functional "underfilling" of the vascular tree. This alteration of the kidney can easily be overcome by coadministration of a carboanhydrase inhibitor (e.g., acetazolamide).
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Affiliation(s)
- H Knauf
- Medizinische Klinik I, St. Bernward Krankenhaus, Hildesheim, Germany
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Abstract
The nephrotic syndrome is associated with an expanded interstitial volume and edema due to sodium and water retention. The mechanisms underlying these abnormalities have been only partially clarified. Renal hypoperfusion has been considered the key event that promotes avid sodium and water reabsorption by the kidney. Hypoperfusion results from hypovolemia, a consequence of urinary protein losses and decreased oncotic pressure. However, in some patients plasma volume is normal or even increased, suggesting that in such cases the cause of sodium and water retention might be independent of systemic events and possibly originates in the kidney. Experimental evidence is now available to support this, but the intrarenal mediator(s) that promote the abnormal salt retention are still not fully clear. Atrial natriuretic peptide (ANP), which increases sodium and water excretion, has been suspected to participate in fluid retention. This is consistent with experimental and human data of a markedly blunted natriuretic and diuretic response to systemic infusion of ANP in the nephrotic syndrome. Recent studies of the mechanisms of the blunted natriuretic and diuretic response to ANP documented an increased activity of renal sympathetic nerves, but the results are controversial. The altered response to ANP also may be related to a defect in the number and affinity of receptor-binding sites for the peptide. Evidence also is available of a possible defect at the level of intracellular cyclic guanosine monophosphate, the second messenger of ANP. The gene encoding for a cyclophilin-like protein, which is increased in sodium-retaining conditions, is upregulated in the kidneys of nephrotic rats, and the infusion of ANP further increases cyclophilin-like protein mRNA. Thus, multiple factors probably act in concert to induce edema formation in the nephrotic syndrome. In this review we specifically address the tubular insensitivity to the natriuretic and diuretic action of ANP, which could be an important initiating event and could possibly contribute to sustaining the edema.
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Affiliation(s)
- N Perico
- Mario Negri Institute for Pharmacological Research, Bergamo, Italy
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Féraille E, Vogt B, Rousselot M, Barlet-Bas C, Cheval L, Doucet A, Favre H. Mechanism of enhanced Na-K-ATPase activity in cortical collecting duct from rats with nephrotic syndrome. J Clin Invest 1993; 91:1295-300. [PMID: 8386183 PMCID: PMC288098 DOI: 10.1172/jci116328] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The maximal hydrolytic activity of Na-K-ATPase is specifically increased in the cortical collecting duct (CCD) of rats with puromycin-induced nephrotic syndrome (NS). This stimulation is independent of aldosterone and of endogenous ouabain-like substance. To investigate the mechanism responsible for this change, we compared the maximal Na-K-ATPase hydrolytic activity, the ouabain sensitive 86Rb influx, the specific [3H]ouabain binding, and the sensitivity of Na-K-ATPase to ouabain in the CCD of control rats and of rats given an intraperitoneal injection of puromycin 7 d before study. Both Na-K-ATPase activity and ouabain-sensitive 86Rb influx increased two-fold in rats with NS (ATPase activity: 34.1 +/- 2.1 vs. 18.0 +/- 0.7 pmol.mm-1 x min-1 +/- SE, n = 6, P < 0.001; Rb influx: 14.4 +/- 0.7 vs. 7.4 +/- 0.4 peq.min-1 +/- SE, n = 6, P < 0.001) whereas specific [3H]ouabain binding decreased in rats with NS (6.9 +/- 0.7 vs. 9.0 +/- 0.6 fmol.mm-1 +/- SE, n = 6, P < 0.005). Therefore, the maximal turnover rate of Na-K-ATPase increased over twofold in rats with NS (5,053 +/- 361 vs. 2,043 +/- 124 cycles.min-1 +/- SE, n = 6, P < 0.001). Analysis of the curves of inhibition of Na-K-ATPase by ouabain showed the presence of two Na-K-ATPase populations in both control and NS rats: a highly sensitive population (apparent Ki: 1.4 x 10(-6) M and 0.9 x 10(-6) M) and a less sensitive moiety (apparent Ki: 2.6 x 10(-4) M and 1.1 x 10(-4) M). The enhancement of Na-K-ATPase activity observed in the CCD of rats with NS was entirely due to the stimulation of the population of Na-K-ATPase with low ouabain sensitivity. These results suggest that a dysregulation of this subclass of Na-K-ATPase might be the primary cause of sodium retention in this model of nephrotic syndrome.
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Affiliation(s)
- E Féraille
- Division de Néphrologie, Hôpital Cantonal Universitaire de Genève, Switzerland
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Valentin JP, Qiu C, Muldowney WP, Ying WZ, Gardner DG, Humphreys MH. Cellular basis for blunted volume expansion natriuresis in experimental nephrotic syndrome. J Clin Invest 1992; 90:1302-12. [PMID: 1328296 PMCID: PMC443174 DOI: 10.1172/jci115995] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Experimental nephrotic syndrome results in sodium retention, reflecting, at least in part, an intrinsic defect in renal sodium handling in the distal nephron. We studied the relationships among plasma atrial natriuretic peptide (ANP) concentration, sodium excretion (UNaV), and urinary cyclic GMP excretion (UcGMPV) in vivo, and the responsiveness of isolated glomeruli and inner medullary collecting duct (IMCD) cells to ANP in vitro, in rats with adriamycin nephrosis (6-7 mg/kg body weight, intravenously). 3-5 wk after injection, rats were proteinuric and had a blunted natriuretic response to intravenous infusion of isotonic saline, 2% body weight given over 5 min. 30 min after onset of the infusion, plasma ANP concentrations were elevated in normals and were even higher in nephrotics. Despite this, nephrotic animals had a reduced rate of UcGMPV after the saline infusion, and accumulation of cGMP by isolated glomeruli and IMCD cells from nephrotic rats after incubation with ANP was significantly reduced compared to normals. This difference was not related to differences in binding of 125I-ANP to IMCD cells, but was abolished when cGMP accumulation was measured in the presence of 10(-3) M isobutylmethylxanthine or zaprinast (M&B 22,948), two different inhibitors of cyclic nucleotide phosphodiesterases (PDEs). Infusion of zaprinast (10 micrograms/min) into one renal artery of nephrotic rats normalized both the natriuretic response to volume expansion and the increase in UcGMPV from the infused, but not the contralateral, kidney. These results show that, in adriamycin nephrosis, blunted volume expansion natriuresis is associated with renal resistance to ANP, demonstrated both in vivo and in target tissues in vitro. The resistance does not appear related to a defect in binding of the peptide, but is blocked by PDE inhibitors, suggesting that enhanced cGMP-PDE activity may account for resistance to the natriuretic actions of ANP observed in vivo. This defect may represent the intrinsic sodium transport abnormality linked to sodium retention in nephrotic syndrome.
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Affiliation(s)
- J P Valentin
- Division of Nephrology, San Francisco General Hospital, California 94110
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Buerkert J, Martin DR, Trigg D, Simon EE. Sodium handling by deep nephrons and the terminal collecting duct in glomerulonephritis. Kidney Int 1991; 39:850-7. [PMID: 2067201 DOI: 10.1038/ki.1991.107] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The present study was designed to characterize the effects of anti-glomerular basement membrane (anti-GBM) glomerulonephritis (GN) on sodium handling by surface nephrons, deep nephrons and the terminal collecting duct segment. Studies were performed in rats during hydropenia and volume expansion. In hydropenia, the glomerular filtration rate (GFR) and sodium excretion tended to be lower in rats with GN than in controls. However, the major differences between the control and GN animals were seen in volume expansion. In the volume expanded groups fractional excretion of sodium was greater in controls (3.20 +/- 0.51%) than in GN (1.20 +/- 0.36%, P less than 0.01). Despite this, delivery to end proximal sites was similar in the two groups in absolute terms and higher in the expanded GN group compared to the expanded controls. Absolute sodium delivery to the bend of the loop of Henle in the expanded GN rats was decreased in absolute terms but increased in fractional terms compared to expanded controls. However, fractional delivery of sodium to the base of the terminal collecting duct was less in GN (3.71 +/- 1.39%) than in controls (7.19 +/- 0.96%, P less than 0.002). In both groups, fractional delivery between tip of the collecting duct fell compared to base (P less than 0.05) but delivery to the tip was again greater in controls (5.49 +/- 1.08%) than in GN (1.51 +/- 0.47%). In GN 62.6 +/- 5.0% of delivered sodium was reabsorbed between collecting duct sites, nearly twofold that of controls (28.8 +/- 9.4%, P less than 0.01). Thus, fractional sodium reabsorption in the collecting duct was enhanced by GN.
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Affiliation(s)
- J Buerkert
- Department of Medicine, University of Arkansas for Medical Sciences, Little Rock
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Simon EE, Merli C, Fry B, Buerkert J. Contribution of superficial nephron segments to sodium excretion in experimental glomerulonephritis. Kidney Int 1989; 36:601-8. [PMID: 2811062 DOI: 10.1038/ki.1989.236] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The present study examined the contribution of individual superficial nephron segments to sodium excretion in antiglomerular basement membrane nephritis in the rat by sampling the same nephron successively from the end and beginning of the distal tubule and end of the proximal tubule. Whole kidney GFR in glomerulonephritic rats was reduced by approximately 40% from controls; absolute sodium excretion was about 25% of normal. Metabolic balance studies in the awake state had suggested that the animals were in sodium balance. Plasma renin levels before and during micropuncture were similar to controls. These findings suggest that the defect in sodium handling is intrinsic to the kidney. Glomerulotubular balance was maintained along the proximal tubule. Sodium reabsorption in the loop of Henle was reduced in absolute terms but was proportional to the load delivered. Due to the decreased absolute sodium reabsorption in the preceding segments, sodium delivery to the beginning of the distal tubule was comparable in the two groups of animals. Along the distal tubule sodium reabsorption was comparable to control animals. Therefore, the avid urinary sodium retention seen during micropuncture was due to increased sodium reabsorption by segments past the superficial proximal tubule and/or by deep nephrons.
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Affiliation(s)
- E E Simon
- Department of Medicine, Jewish Hospital of St. Louis, Washington University, Missouri
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Affiliation(s)
- D J Salant
- Evans Memorial Department of Clinical Research, University Hospital, Boston University Medical Center, Massachusetts
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Tulassay T, Rascher W, Schärer K. Intra- and extrarenal factors of oedema formation in the nephrotic syndrome. Pediatr Nephrol 1989; 3:92-100. [PMID: 2702097 DOI: 10.1007/bf00859635] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The role of intra- and extrarenal factors in oedema formation in children with nephrotic syndrome is reviewed. Oedema reflects an abnormal accumulation of fluid within the interstitial tissue. At the capillary level oedema develops when increased lymph flow is no longer effective for the removal of interstitial fluid and the maintenance of intravascular volume. Alterations of intrarenal haemodynamics and tubular sodium reabsorption contribute to sodium retention. Recent studies suggest that during oedema formation reduced effective circulatory volume triggers changes in various hormonal systems, such as renin-angiotensin-aldosterone, noradrenaline, dopamine, vasopressin, prostaglandins and natriuretic factors, which contribute to sodium and water retention. It appears that the release of atrial natriuretic peptide following central volume expansion is responsible for the increased urine flow and natriuresis after intravenous administration of albumin.
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Affiliation(s)
- T Tulassay
- Division of Pediatric Nephrology, Universitäts-Kinderklinik, Heidelberg, Federal Republic of Germany
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Atrial natriuretic peptide and the renal response to hypervolemia in nephrotic humans. Kidney Int 1988; 34:825-31. [PMID: 2974905 DOI: 10.1038/ki.1988.256] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
To elucidate the abnormality of body fluid homeostasis that attends the nephrotic syndrome, we compared the atrial hormonal and renal excretory and vasomotor responses to water immersion of nephrotic patients (N = 10) with those of healthy controls (N = 9). Nephrotics exhibited depressed baseline levels of atrial natriuretic peptide (ANP, P less than 0.05) and lower rates of urine flow and sodium excretion (P less than 0.01). Although immersion-induced hypervolemia increased plasma ANP to equivalent levels (75 +/- 19 vs. 60 +/- 6 pg/ml), the disparity in corresponding urinary flow (5 +/- 1 vs. 13 +/- 2 ml/min, P less than 0.01) and sodium excretion (171 +/- 42 vs. 540 +/- 65 muEq/min, P less than 0.01) grew larger. In contrast, immersion caused an equivalent reduction of renal vascular resistance by 16 and 17%, respectively (P less than 0.01). Despite higher renal plasma flow and lower oncotic pressure of plasma, the glomerular filtration rate remained constant during immersion in both groups. Similar constancy of fractional clearances of dextrans of graded size suggests that immersion may have lowered the glomerular transcapillary hydraulic pressure difference (delta P). We conclude that renal vasomotor responsiveness to hypervolemia is preserved in nephrotics, but that the mediatory role of ANP in this response is uncertain. By contrast, diminished responsiveness of the distal nephron to the natriuretic action of endogenous ANP could contribute to edema formation in the nephrotic syndrome.
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Disordered Sodium Metabolism: Sodium Retention States. Crit Care Clin 1987. [DOI: 10.1016/s0749-0704(18)30519-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Abstract
Modern views of the pathogenesis and natural history of nephrotic syndrome have changed substantially since the early studies by Cotugno and Bright. Contrary to beliefs held 20 years ago, we do not possess a unique satisfying explanation for the induction, maintenance, and resolution of nephrotic edema, and many concepts firmly established as "classic" are now being revised or reconsidered. These include the relationship between urinary protein losses and hypoalbuminemia, which is complicated by several factors such as daily protein intake, albumin catabolism, and the possible role of albumin loss at extrarenal sites. The influence of lowered plasma albumin on the decrease in plasma volume is also quite complex, due to technical difficulties in measuring plasma volume and turnover of radio-labeled albumin. The most contentious areas are how sodium and water retention are initiated and maintained and the relationship between hypoalbuminemia, plasma oncotic pressure, and edema. While aldosterone excretion and plasma concentrations are elevated in nephrotic patients, data on the renin-angiotensin system are controversial and the renal handling of sodium is related to a host of factors including glomerular filtration rate, altered proximal tubular reabsorption, and the role of vasodilators or vasoconstrictors. The complications of nephrotic syndrome are protean and relatively common. Among those are acute renal failure, thrombosis, infections, and hyperlipidemia. Since the introduction of percutaneous biopsy, the spectrum of lesions underlying nephrotic syndrome has widened considerably, the most common being minimal change, especially in children. There are very few prognostic indicators by which response to treatment may be predicted and these include persistent microscopic hematuria.
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Tulassay T, Rascher W, Lang RE, Seyberth HW, Schärer K. Atrial natriuretic peptide and other vasoactive hormones in nephrotic syndrome. Kidney Int 1987; 31:1391-5. [PMID: 2956451 DOI: 10.1038/ki.1987.154] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Plasma levels of atrial natriuretic peptide (ANP), arginine vasopressin (AVP), renin activity (PRA), aldosterone (PA), catecholamines and urinary prostaglandins (PG), as well as renal function were measured in children in the edematous state of the nephrotic syndrome before and after infusion of human serum albumin. Before albumin infusion, plasma levels of AVP, PRA, PA and noradrenaline (NA) and urinary excretion of PGE2, PGE-Met, PGF2 alpha were elevated. The mean value of plasma ANP was in the normal range. Albumin infusion produced a 36% increase in the calculated plasma volume. It was associated with a fivefold rise in the plasma level of ANP (31.6 +/- 22.6 vs. 151.4 +/- 52 fmol/ml mean, SD), and a significant fall in the levels of PRA, AVP, PA, and NA. Similarly, urinary concentration of PGE2, PGE-Met and PGF2 alpha fell. Urine flow, GFR, UNaV, FENa, and COsm increased significantly, while CH2O remained unchanged. The diuresis, natriuresis and GFR correlated with the level of plasma ANP, while urinary sodium excretion did not correlate with PA or NA levels. These findings suggest that ANP plays an important role in albumin induced natriuresis in children with nephrotic syndrome.
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Chachati A, Godon JP. Distal blockade in experimental glomerulonephritis: the role of the diluting segment in sodium retention. ARCHIVES INTERNATIONALES DE PHYSIOLOGIE ET DE BIOCHIMIE 1985; 93:299-306. [PMID: 2421667 DOI: 10.3109/13813458509079610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In the light of accumulating evidence implicating the diluting segment as the site of final regulation of sodium excretion by the nephron, we produced in this experiment distal blockade in anti-glomerular basement membrane (GBM) glomerulonephritic (GN) rats by the administration of furosemide and polythiazide. This allowed to dissociate the sodium reabsorption that occurs in the proximal tubule from the one that occurs more distally and permitted an appreciation of the rôle played by the diluting segment in the sodium retention of anti GBM GN. In a previous experiment we showed that GN conscious or anaesthetized rats presented an increase in Na tubular reabsorption and failed to raise their fractional and absolute excretion of sodium as normal one did after rapid volume expansion. In this study distal blockade corrected almost completely the difference in sodium excretion that existed between GN and normal groups before the administration of diuretics, pointing to the important rôle played by the diluting segment in the sodium retention of experimental GN.
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Zamlauski-Tucker MJ, Van Liew JB, Noble B. Pathophysiology of the kidney in rats with Heymann nephritis. Kidney Int 1985; 28:504-12. [PMID: 3877841 DOI: 10.1038/ki.1985.157] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Alterations in kidney function were assessed early in the course of Heymann nephritis that was induced in rats by immunization with Fx1A, an extract prepared from rat kidney cortex. Whole kidney and single nephron function were evaluated by clearance and micropuncture techniques. Kidney function was studied in stage 1 of Heymann nephritis, before the onset of proteinuria, and in stage 2, when antibodies are deposited along the brush border of proximal tubules. Although overall kidney function was similar in rats in stage 1 and normal controls, glucose reabsorption was somewhat depressed in the first part of the proximal convoluted tubule in stage 1. Both whole kidney and single nephron glomerular filtration rates were depressed in stage 2. Proteinuria in stage 2 was characterized by an increased albumin sieving coefficient, which resulted in an elevated excretion of albumin. Furthermore, several proximal tubule functions (glucose and fluid reabsorption and PAH extraction) were substantially depressed in stage 2. These findings demonstrate that immunological injury to the proximal tubules in stage 2 of Heymann nephritis produces a significant impairment of proximal function.
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34
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Abstract
Renal sodium handling was studied in 23 children at three different stages of the minimal change nephrotic syndrome--the oedema forming state, proteinuric steady state, and remission. Clearances of inulin and para-aminohippuric acid and urinary sodium excretion were determined basally, after intravenous infusion of isotonic saline and hyperoncotic albumin, and after furosemide injection. Absolute and fractional basal sodium excretion were significantly lower in oedema forming patients than in proteinuric patients in steady state, and non-proteinuric patients. In contrast to proteinuric patients in steady state and non-proteinuric patients, the oedema forming patients failed to respond to isotonic saline infusion with increased sodium excretion. After diuretic blockade with furosemide, the fractional sodium excretion of the oedema forming patients increased to values no different from those of the non-proteinuric patients, whereas the fractional sodium excretion of the steady state patients increased to significantly higher values. The plasma aldosterone concentration was within normal limits in 11 of 14 proteinuric patients, and did not correlate with the basal sodium excretion. Thus, sodium retention in the minimal change nephrotic syndrome was found only in oedema forming patients, and since this is not related to the plasma aldosterone concentration it may be caused by an intrarenal mechanism, probably sited in distal parts of the nephron.
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35
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Usberti M, Federico S, Meccariello S, Cianciaruso B, Balletta M, Pecoraro C, Sacca L, Ungaro B, Pisanti N, Andreucci VE. Role of plasma vasopressin in the impairment of water excretion in nephrotic syndrome. Kidney Int 1984; 25:422-9. [PMID: 6727137 DOI: 10.1038/ki.1984.34] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
To verify whether or not an increased secretion of ADH may cause the water retention commonly observed in nephrotic syndrome, 16 nephrotic patients and 13 normal control subjects were studied in basal conditions and following a water load or an iso-osmotic blood volume expansion by 20% albumin infusion. In the basal condition there were no differences in plasma ADH, urine output, urinary osmolality (UOsm), and plasma renin activity between nephrotic patients and control subjects; POsm, PNa+, UNaV, and blood volume (BV) instead, were significantly lower in nephrotic patients than in control subjects. Following the water load control subjects reached a minimal UOsm of 82 +/- 12 mOsm/kg at 60 min and excreted completely the ingested water in 150 min; nephrotic patients reached a minimal UOsm of 160 +/- 111 mOsm/kg at 120 min, and the water was eliminated completely in 240 min. Plasma ADH decreased significantly in the first hour following water load only in control subjects. A significant direct correlation was observed between plasma ADH and POsm in control subjects (ADH = -85 + 0.30 POsm, P less than 0.001) but not in nephrotic patients. Plasma ADH was inversely correlated with BV in nephrotic patients (ADH = 15.47 -0.17 BV, P less than 0.001) but not in normal control subjects. In nephrotic patients with reduced BV the expansion of BV with 20% albumin was effective in reducing the plasma levels of ADH and promoting a water diuresis. Our results demonstrate a sustained volume mediated secretion of ADH in the nephrotic syndrome, which is responsible for the impairment in water excretion.
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36
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Primary Renal Sodium Retention in the Nephrotic Syndrome. Nephrology (Carlton) 1984. [DOI: 10.1007/978-1-4612-5284-9_45] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Ichikawa I, Rennke HG, Hoyer JR, Badr KF, Schor N, Troy JL, Lechene CP, Brenner BM. Role for intrarenal mechanisms in the impaired salt excretion of experimental nephrotic syndrome. J Clin Invest 1983; 71:91-103. [PMID: 6848563 PMCID: PMC436841 DOI: 10.1172/jci110756] [Citation(s) in RCA: 205] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
A unilateral model of puromycin aminonucleoside (PAN)-induced albuminuria was produced in Munich-Wistar rats to examine the mechanisms responsible for renal salt retention. 2 wk after selective perfusion of left kidneys with PAN (n = 8 rats) or isotonic saline (control, n = 7 rats), increases in albumin excretion and decreases in sodium excretion were demonstrated in PAN-perfused but not in nonperfused kidneys of PAN-treated rats although systemic plasma protein concentration remained at control level. Total kidney glomerular filtration rate (GFR) and superficial single nephron (SN) GFR were also reduced selectively in PAN-perfused kidneys, on average by approximately 30%, due primarily to a marked decline in the glomerular capillary ultrafiltration coefficient (Kf), which was also confined to PAN-perfused kidneys. Values for absolute proximal reabsorption (APR) were also selectively depressed in PAN-perfused kidneys, in keeping with a similarly selective decline in peritubular capillary oncotic pressure measured in these kidneys, the latter also a consequence of the fall in Kf. In a separate group of seven PAN-treated rats, however, no differences were detected between PAN-perfused and nonperfused kidneys in the absolute amount of sodium reaching the early (0.77 +/- 0.09 neq/min vs. 0.74 +/- 0.08, P greater than 0.40) and late portions of superficial distal tubules (0.31 +/- 0.02) neq/min vs. 0.32 +/- 0.05, P greater than 0.50), despite the lesser filtered load of sodium in PAN-perfused kidneys. Suppressed sodium reabsorption in both proximal convoluted tubules and short loops of Henle of PAN-perfused kidneys contributed to this equalization of sodium delivery rates to the late distal tubule, as did comparable reabsorption along distal convolutions. In two additional groups of PAN-treated rats, infusion of saralasin (0.3 mg/kg per h, i.v.) led to substantial increases in total kidney GFR and SNGFR in PAN-perfused but not in nonperfused kidneys. Despite these increases in total and SNGFR, urinary sodium excretion by PAN-perfused kidneys remained at a level far below that for nonperfused kidneys, again indicating that the antinatriuresis characterizing the PAN-perfused kidney is due to alterations in sodium handling by the tubules rather than changes in GFR. These results therefore indicate (a) that reductions in Kf and depressed sodium reabsorption by proximal tubules and Henle's loop segments in this model are brought about by intrarenal rather than circulating or systemic factors, and (b) assuming that superficial nephrons are representative of the entire nephron population, renal salt retention in this model is due primarily to intrarenal factor(s) acting beyond the distal convolution.
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Abstract
Edema is a collection of fluid within the body's interstitial space which occurs when there is an alteration of the Starling forces which control transfer of fluid from the vascular compartment to surrounding tissue spaces. Generalized edema results when altered Starling forces affect all capillary beds, such as occurs in cardiac failure, cirrhosis, and nephrotic syndrome. Common to these conditions is the development of increased total body sodium and water content. The kidneys play an essential role in the retention of this sodium and water. In this article we shall discuss the signals the kidneys receive for sodium and water retention in these edematous disorders (afferent mechanisms). We shall also examine the means by which the kidney responds to these signals and retains sodium and water (efferent mechanisms). As shall become apparent these edematous states may share many of the same afferent and efferent mechanisms for sodium and water retention.
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Abstract
Autodigestion of activated Hageman factor (HFa) yields a 40,000-mol wt activated enzyme as well as Hageman factor fragment (HFf); HFf consists of two molecular weight species of 28,500 and 30,000. We have investigated the structure of these active fragments and demonstrate that upon reduction, each possesses a heavy chain of 28,000. The associated light chains were identified by subjecting iodinated proteins to two-dimensional slab gel electrophoresis in which the second dimension is run reduced. The 40,000-dalton enzyme has a light chain of 15,000, the 30,000-dalton form of HFf has a light chain of 2,000 and we have suggestive evidence of a light chain associated with the 28,500-dalton form of HFf (putative mol wt approximately 500). We also demonstrate that the 30,000-dalton form of HFf precedes the 28,500 form. These data indicate that digestion of native HF to form HFa precedes cleavages that fragment the molecule and diminish its molecular weight. The 28,500-dalton light chain of HFa becomes the heavy chain of each of the fragmentation products while cleavage at different points along the heavy chain of HFa determines which fragments will be produced. In contrast to autoactivation, kallikrein digestion of HFa yields primarily HFf; however, the 40,000-dalton enzyme may be seen when prekallikrein-deficient (Fletcher trait) plasma is activated.
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Abstract
In the steady state, urinary excretion of sodium is closely matched to dietary salt intake. Given rigorous defense of extracellular fluid osmolality, it is the quantity of sodium in the extracellular fluid that determines the volume of this compartment. Changes in extracellular fluid volume are detected by volume sensors located in the intrathoracic vascular bed, kidney and other organs. These mechanoreceptors gauge the adequacy of intravascular volume, relative to capacitance, at various sites within the circulation. The perception of a change in the normal relationship between intravascular volume and circulatory capacity evokes a host of renal effector mechanisms that lead ultimately to physiologically appropriate changes in urinary sodium excretion. These effector mechanisms involve physical adjustments in the glomerular filtration rate, renal microvascular hemodynamics and peritubular capillary Starling forces, tubule fluid composition, flow rate and transtubular ion gradients. Neural and humoral pathways are also involved and, among the latter, angiotensin II, aldosterone, prostaglandins and kinins have been studied extensively. The continuous interaction between these sensor and effector mechanisms serves to ensure near-constancy of the extracellular fluid volume, a condition essential for optimal circulatory performance.
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Mendrick DL, Noble B, Brentjens JR, Andres GA. Antibody-mediated injury to proximal tubules in Heymann nephritis. Kidney Int 1980; 18:328-43. [PMID: 7007708 DOI: 10.1038/ki.1980.143] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
To evaluate the hypothesis that antibody-mediated damage to proximal tubules (PT) could be a feature of Heymann nephritis (HN), we studied the kidneys of rats in different stages of the disease by light, immunoflourescence (IF), transmission, and scanning electron microscopy. The observations of morphology were correlated with titers of circulating antibodies directed against the brush border (BB) and with proteinuria. Antibody titers reached a maximum 5 to 7 weeks after immunization with Fx1A, coincident with the onset of proteinuria. IgG and C3 were deposited along the BB of PT in all animals within the first week of proteinuria. BB antibodies were present in the urine of those rats. As antibody titers declined, a decrease in the extent of in vivo IgG deposition along the BB was also noted. The results of indirect IF tests, by using BB antibodies on kidneys of rats with HN of 3 to 4 months' duration, suggested extensive loss of the BB antigen(s) from the PT. Numerous granular deposits of IgG were present along the basement membrane of PT at that time. Study of kidney histology revealed that deposition of IgG and C3 along the BB of PT was associated with extensive loss of microvilli, as well as degeneration and proliferation of PT cells. Subepithelial electron-dense deposits were present along the basement membrane of PT. In rats with HN of more than 4 months' duration, with little or no circulating BB antibodies and persistent proteinuria, IgG and C3 were found in minimal amounts along BB. Examination by light and electron microscopy provided evidence of partial recovery of PT lesions in those kidneys. Rats with similar proteinuria resulting from chronic serum sickness did not have similar abnormalities of PT. These observations are consistent with the interpretation that, in rats with HN, BB antibodies induce cytotoxic injury to PT.
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Tikkanen I, Fyhrquist F, Miettinen A, Törnroth T. Autologous immune complex nephritis and DOCA-NaCl load: a new model of hypertension. ACTA PATHOLOGICA ET MICROBIOLOGICA SCANDINAVICA. SECTION A, PATHOLOGY 1980; 88:241-50. [PMID: 6449827 DOI: 10.1111/j.1699-0463.1980.tb02492.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
In order to explore immunological features of hypertension, we studied autologous immune complex nephritis (Heymann nephritis) combined with DOCA-NaCl treatment. This combination resulted in hypertension and increased heart weight whereas DOCA-NaCl treatment alone induced only a slight elevation of blood pressure and a moderate increase in heart weight. Nephritic rats without DOCA-NaCl load remained normotensive, their heart weights being comparable to those of controls. This new model of hypertension was neither characterized by azotemia nor by reduced renal excretory capacity. Hypertension was not renin-angiotensin-dependent. DOCA-NaCl treatment accelerated the development of proteinuria. In the hypertensive rats, systolic blood pressure to daily urinary protein excretion. Renal histopathology revealed changes resembling those of malignant nephrosclerosis. Immunohistology and electron microscopy showed a typical membranous glomerulonephritis in all immunized animals. It was concluded that immune complex disease of the Heymann nephritis type may interfere with normal hemodynamic adaptation to hypervolemic sodium load, resulting in hypertension.
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Kuroda S, Aynedjian HS, Bank N. A micropuncture study of renal sodium retention in nephrotic syndrome in rats: evidence for increased resistance to tubular fluid flow. Kidney Int 1979; 16:561-71. [PMID: 548600 DOI: 10.1038/ki.1979.166] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Micropuncture studies were carried out in surface nephrons of rats with nephrotoxic-serum (NTS)-induced nephrotic syndrome during a period of active sodium and water retention. It was found that hydrostatic pressure and tubular diameter were increased in the proximal tubules (13.4 +/- 0.2 vs. 10.4 +/- 0.2 mm Hg; 31.3 +/- 0.9 vs. 18.4 +/- 0.7 mu), whereas pressure and tubular diameter were normal in the distal tubules. Single nephron glomerular filtration rate (SNGFR) was decreased and fractional reabsorption of fluid was markedly increased in the proximal tubules (74.1 vs. 61.7%). The increased pressure gradient between the proximal and distal tubules suggests a condition of increased resistance to flow between the proximal and distal tubules. Microinfusion of proximal tubules with an isotonic "equilibrium" solution led to little or no rise in intratubular pressure in normal rats but it led to a significant rise in nephrotic rats. When proximal tubules of normal rats were infused with a solution containing 100 mg/100 ml albumin, pressure rose to levels observed in nephrotic rats. The mechanism of the increased resistance to flow appeared to be related, therfore, to the presence of protein in the tubular fluid. Sodium retention in the nephrotic animals might be attributed to the reduction in GFR. In other types of renal disease in animals and man with comparable or greater reductions in GFR, sodium retention does not occur, however, and fractional excretion of sodium in the urine is increased in proportion to the reduction in GFR. Thus, the rise in proximal fractional reabsorption secondary to impaired fluid flow could be an important factor in the sodium retention of this disease.
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Usberti M, Federico S, Cianciaruso B, Costanzo R, Russo D, Andreucci VE. Relationship between serum albumin concentration and tubular reabsorption of glucose in renal disease. Kidney Int 1979; 16:546-51. [PMID: 548598 DOI: 10.1038/ki.1979.164] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Micropuncture studies in rats and dogs have provided evidence for a cause-and-effect relationship between peritubular protein concentration and proximal tubular reabsorption (PTR). If this effect is obtained in man, hypoalbuminemia in nephrotic syndrome should lead to a fall in PTR. Sodium excretion, however, is very low in nephrotic patients; but this sodium retention may be due to distal over-reabsorption. Glucose may be used as a marker of PTR. Because of the linkage between glucose and sodium, glucose reabsorption is expected to be suppressed when PTR of sodium is suppressed. Glucose titration studies were performed in 21 patients with chronic glomerulonephritis without renal failure divided in three groups: I (six patients) with serum albumin greater than 3 g/100 ml; II (five patients) with serum albumin of 2 to 3 g/100 ml; and III (10 patients with edema and nephrotic syndrome) with serum albumin less than 2 g/100 ml. The minimum threshold for glucose decreased in nephrotic patients (group III), and its fall was related directly to hypoalbuminemia. The splay of titration curve was markedly increased in group III when compared to the titration curves of patients without nephrotic syndrome (groups I and II). The splay point was 0.78 in group I, 0.52 in group II, and 0.37 in group III. These data provide evidence that glucose reabsorption is decreased in nephrotic syndrome and are consistent with a fall in PTR in nephrotic syndrome.
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