Aldosterone-dependent and -independent regulation of the epithelial sodium channel (ENaC) in mouse distal nephron

Nesterov, Viatcheslav; Dahlmann, Anke; Krueger, Bettina; Bertog, Marko; Loffing, Johannes; Korbmacher, Christoph

doi:10.1152/ajprenal.00247.2012

Cited by 91 publications

(117 citation statements)

References 49 publications

Supporting

Mentioning

102

Contrasting

Order By: Relevance

“…29,42,43 Our immunofluorescence and functional data are also in good agreement with patch-clamp studies on isolated early and late ASDN segments from AS +/+ and AS 2/2 mice that indicated that ENaC regulation in the early ASDN is largely aldosterone independent. 44 Here, we provide a possible explanation for the aldosterone-independent activity of ENaC in the early ASDN of AS 2/2 mice. AS 2/2 mice have very high 26 This probably does not directly contribute to the regulation of K + homeostasis, but may compensate for the loss of aldosterone at least in part by ensuring a residual ENaC activity in the kidney of AS 2/2 mice.…”

Section: Discussionmentioning

confidence: 70%

Mechanisms of Renal Control of Potassium Homeostasis in Complete Aldosterone Deficiency

Todkar

Picard²,

Loffing‐Cueni³

et al. 2015

Journal of the American Society of Nephrology

Self Cite

View full text Add to dashboard Cite

Aldosterone-independent mechanisms may contribute to K + homeostasis. We studied aldosterone synthase knockout (AS 2/2 ) mice to define renal control mechanisms of K + homeostasis in complete aldosterone deficiency. AS 2/2 mice were normokalemic and tolerated a physiologic dietary K + load (2% K + , 2 days) without signs of illness, except some degree of polyuria. With supraphysiologic K + intake (5% K + ), AS 2/2 mice decompensated and became hyperkalemic. High-K + diets induced upregulation of the renal outer medullary K + channel in AS 2/2 mice, whereas upregulation of the epithelial sodium channel (ENaC) sufficient to increase the electrochemical driving force for K + excretion was detected only with a 2% K + diet. Phosphorylation of the thiazide-sensitive NaCl cotransporter was consistently lower in AS 2/2 mice than in AS +/+ mice and was downregulated in mice of both genotypes in response to increased K + intake.Inhibition of the angiotensin II type 1 receptor reduced renal creatinine clearance and apical ENaC localization, and caused severe hyperkalemia in AS 2/2 mice. In contrast with the kidney, the distal colon of AS 2/2 mice did not respond to dietary K + loading, as indicated by Ussing-type chamber experiments. Thus, renal adaptation to a physiologic, but not supraphysiologic, K + load can be achieved in aldosterone deficiency by aldosteroneindependent activation of the renal outer medullary K + channel and ENaC, to which angiotensin II may contribute. Enhanced urinary flow and reduced activity of the thiazide-sensitive NaCl cotransporter may support renal adaptation by activation of flow-dependent K + secretion and increased intratubular availability of Na + that can be reabsorbed in exchange for K + secreted.

show abstract

Section: Discussionmentioning

confidence: 70%

Mechanisms of Renal Control of Potassium Homeostasis in Complete Aldosterone Deficiency

Todkar

Picard²,

Loffing‐Cueni³

et al. 2015

Journal of the American Society of Nephrology

Self Cite

View full text Add to dashboard Cite

show abstract

“…We speculate that the higher baseline potential difference and hence, equivalent current, and the insensitivity to aldosterone observed with primary cells in mpkCCD c14 media may have favored a DCT2/CNT phenotype. In contrast, cells incubated with REBM, which exhibited a lower baseline but higher aldosterone-stimulated sodium current, resembled a CCD phenotype (43). REBM has three known differences from mpkCCD c14 media: 1) a lack of supplemental selenium; 2) substitution of dexamethasone with hydrocortisone; and 3) the presence of epinephrine.…”

Section: Discussionmentioning

confidence: 96%

“…In contrast, expression of markers for the proximal tubule, including SGLT2 and GLUT2 (65), was significantly enriched in unbound preparations. Surprisingly, expression of markers for the distal cortical tubule, including NCC (DCT1 and DCT2), TRPM6 (DCT1 Ͼ DCT2) (72), ENaC (DCT2 to principal cells of the CNT and CCD) (43), and pendrin (intercalated cells from CCD) (25,40), were enriched in DBA-bound preparations. This was unexpected because DBA staining by immunofluorescence microscopy was much stronger in only CNT and CCD (Fig.…”

Section: Dba-linked Biotin Selectively Binds the Connecting Tubulementioning

confidence: 97%

Harvest and primary culture of the murine aldosterone-sensitive distal nephron

Labarca

Nizar

Walczak

et al. 2015

American Journal of Physiology-Renal Physiology

View full text Add to dashboard Cite

Labarca M, Nizar JM, Walczak EM, Dong W, Pao AC, Bhalla V. Harvest and primary culture of the murine aldosterone-sensitive distal nephron. Am J Physiol Renal Physiol 308: F1306 -F1315, 2015. First published March 25, 2015 doi:10.1152/ajprenal.00668.2014The aldosterone-sensitive distal nephron (ASDN) exhibits axial heterogeneity in structure and function from the distal convoluted tubule to the medullary collecting duct. Ion and water transport is primarily divided between the cortex and medulla of the ASDN, respectively. Transcellular transport in this segment is highly regulated in health and disease and is integrated across different cell types. We currently lack an inexpensive, high-yield, and tractable technique to harvest and culture cells for the study of gene expression and physiological properties of mouse cortical ASDN. To address this need, we harvested tubules bound to Dolichos biflorus agglutinin lectin-coated magnetic beads from the kidney cortex and characterized these cell preparations. We determined that these cells are enriched for markers of distal convoluted tubule, connecting tubule, and cortical collecting duct, including principal and intercalated cells. In primary culture, these cells develop polarized monolayers with high resistance (1,000-1,500 ⍀ * cm 2 ) and maintain expression and activity of key channels. These cells demonstrate an amiloride-sensitive short-circuit current that can be enhanced with aldosterone and maintain measurable potassium and anion secretion. Our method can be easily adopted to study the biology of the ASDN and to investigate phenotypic differences between wild-type and transgenic mouse models.

show abstract

“…However, we do not exclude that the CD may still play an important role under challenging conditions, even if ENaC deletion per se in this segment does not seem to be a prerequisite for sodium and potassium balance. 7 Indeed, two recent studies unveil an ENaC regulation largely independent from aldosterone 17 and likely dependent on vasopressin, 31 suggesting that sodium but also, potassium handling might be regulated in a cell type-and nephron segment-specific manner. In conclusion, Scnn1a…”

Section: Aldosterone-independent Regulation Of Ncc In Scnn1amentioning

confidence: 99%

Severe Salt–Losing Syndrome and Hyperkalemia Induced by Adult Nephron–Specific Knockout of the Epithelial Sodium Channel α-Subunit

Perrier

Boscardin

Malsure

et al. 2015

JASN

Self Cite

View full text Add to dashboard Cite

Systemic pseudohypoaldosteronism type 1 (PHA-1) is a severe salt-losing syndrome caused by loss-of-function mutations of the amiloride-sensitive epithelial sodium channel (ENaC) and characterized by neonatal lifethreatening hypovolemia and hyperkalemia. The very high plasma aldosterone levels detected under hypovolemic or hyperkalemic challenge can lead to increased or decreased sodium reabsorption, respectively, through the Na + /Cl 2 cotransporter (NCC). However, the role of ENaC deficiency remains incompletely defined, because constitutive inactivation of individual ENaC subunits is neonatally lethal in mice. We generated adult inducible nephron-specific aENaC-knockout mice (Scnn1a) that exhibit hyperkalemia and body weight loss when kept on a regular-salt diet, thus mimicking PHA-1. Compared with control mice fed a regular-salt diet, knockout mice fed a regular-salt diet exhibited downregulated expression and phosphorylation of NCC protein, despite high plasma aldosterone levels. In knockout mice fed a high-sodium and reduced-potassium diet (rescue diet), although plasma aldosterone levels remained significantly increased, NCC expression returned to control levels, and body weight, plasma and urinary electrolyte concentrations, and excretion normalized. Finally, shift to a regular diet after the rescue diet reinstated the symptoms of severe PHA-1 syndrome and significantly reduced NCC phosphorylation. In conclusion, lack of ENaC-mediated sodium transport along the nephron cannot be compensated for by other sodium channels and/or transporters, only by a high-sodium and reduced-potassium diet. We further conclude that hyperkalemia becomes the determining factor in regulating NCC activity, regardless of sodium loss, in the ENaC-mediated salt-losing PHA-1 phenotype.

show abstract

Aldosterone-dependent and -independent regulation of the epithelial sodium channel (ENaC) in mouse distal nephron

Cited by 91 publications

References 49 publications

Mechanisms of Renal Control of Potassium Homeostasis in Complete Aldosterone Deficiency

Mechanisms of Renal Control of Potassium Homeostasis in Complete Aldosterone Deficiency

Harvest and primary culture of the murine aldosterone-sensitive distal nephron

Severe Salt–Losing Syndrome and Hyperkalemia Induced by Adult Nephron–Specific Knockout of the Epithelial Sodium Channel α-Subunit

Contact Info

Product

Resources

About