scholarly journals Collecting duct-specific endothelin B receptor knockout increases ENaC activity

2012 ◽  
Vol 302 (1) ◽  
pp. C188-C194 ◽  
Author(s):  
Vladislav Bugaj ◽  
Elena Mironova ◽  
Donald E. Kohan ◽  
James D. Stockand
Keyword(s):  
Blood Pressure ◽  
Collecting Duct ◽  
Endothelin Receptors ◽  
Sodium Retention ◽  
Wild Type ◽  
Open Probability ◽  
Endothelin System ◽  
Etb Receptor ◽  
Endothelin B ◽  
Patch Clamp Electrophysiology

Collecting duct (CD)-derived endothelin-1 (ET-1) acting via endothelin B (ETB) receptors promotes Na+ excretion. Compromise of ET-1 signaling or ETB receptors in the CD cause sodium retention and increase blood pressure. Activity of the epithelial Na+ channel (ENaC) is limiting for Na+ reabsorption in the CD. To test for ETB receptor regulation of ENaC, we combined patch-clamp electrophysiology with CD-specific knockout (KO) of endothelin receptors. We also tested how ET-1 signaling via specific endothelin receptors influences ENaC activity under differing dietary Na+ regimens. ET-1 significantly decreased ENaC open probability in CD isolated from wild-type (WT) and CD ETA KO mice but not CD ETB KO and CD ETA/B KO mice. ENaC activity in WT and CD ETA but not CD ETB and CD ETA/B KO mice was inversely related to dietary Na+ intake. ENaC activity in CD ETB and CD ETA/B KO mice tended to be elevated under all dietary Na+ regimens compared with WT and CD ETA KO mice, reaching significance with high (2%) Na+ feeding. These results show that the bulk of ET-1 inhibition of ENaC activity is mediated by the ETB receptor. In addition, they could explain the Na+ retention and elevated blood pressure observed in CD ET-1 KO, CD ETB KO, and CD ETA/B KO mice consistent with ENaC regulation by ET-1 via ETB receptors contributing to the antihypertensive and natriuretic effects of the local endothelin system in the mammalian CD.

The vasoconstrictor endothelin system involvement in chronic kidney diseases pathogenesis is now the most often employed treatment method

2021 ◽  
Author(s):  
Moataz Dowaidar
Keyword(s):  
Blood Pressure ◽  
Kidney Diseases ◽  
Collecting Duct ◽  
Treatment Method ◽  
Chronic Kidney Diseases ◽  
System Involvement ◽  
Duct Cells ◽  
Vasa Recta ◽  
Etb Receptor ◽  
Collecting Duct Cells

Over 30,000 publications have been published about the vasoconstrictor endothelin-1, which was identified by Yanagisawa and co-workers in 1988. While the evidence is quite compelling, scientists can only speculate on how the endothelin (ET) system affects blood pressure and renal function at this time. ET system involvement in chronic kidney diseases (CKD) pathogenesis is now the most often employed treatment method. ET1, ET2, and ET3 are all members of the endothelin family. Endothelium, renal, and smooth muscle cells all generate ET-1, a significant isoform found in both cardiovascular and renal systems.Kidney cells act on, and contain, ET-1. The ETA receptor is found in the brain and medulla, but not in the vasa recta or glomeruli. Epithelial and endothelial cells contain the ETB receptor, which is most prominent in collecting duct cells. 3 In several experiments, ET-1 has been established to be largely a preglomerular vasoconstrictor. Mesangial proliferation, contraction, and collagen production are regulated by ET-1 and ETB receptors in podocytes. The epithelium in the collecting duct cells in the medulla is important in controlling Na excretion and BP. Without the ET-1 gene, the mice have hypertension and reduced natriuresis in response to salt loading. Et-1, ETB receptor, and hypertension are shown in mice that have lost the ETB receptor gene. There is no correlation between blood pressure regulation and natriuresis.Combined disruption of the ETA and ETB receptors has greater effects on blood pressure and Na reabsorption than when ETB receptor activity is missing. It appears that the ETB receptor doesn't work until ETB is present. Collecting duct-derived ET receptors reduces the transport of sodium. Src kinase and MAPK1/2 decrease epidermal Na channel (ENaC) function, decreasing water and salt reabsorption. Moreover, inner medullary collecting duct cells and vasa recta-bearing cells will release NO, which decreases sodium transport.

scholarly journals Acute Downregulation of ENaC by EGF Involves the PY Motif and Putative ERK Phosphorylation Site

2007 ◽  
Vol 130 (3) ◽  
pp. 313-328 ◽  
Author(s):  
Rebecca A. Falin ◽  
Calvin U. Cotton
Keyword(s):  
Kinase Inhibitor ◽  
Collecting Duct ◽  
Phosphorylation Site ◽  
Surface Expression ◽  
Wild Type ◽  
Open Probability ◽  
Erk Phosphorylation ◽  
C Terminus ◽  
Py Motif ◽  
Erk Kinase

The epithelial sodium channel (ENaC) is expressed in a variety of tissues, including the renal collecting duct, where it constitutes the rate-limiting step for sodium reabsorption. Liddle's syndrome is caused by gain-of-function mutations in the β and γ subunits of ENaC, resulting in enhanced Na reabsorption and hypertension. Epidermal growth factor (EGF) causes acute inhibition of Na absorption in collecting duct principal cells via an extracellular signal–regulated kinase (ERK)–dependent mechanism. In experiments with primary cultures of collecting duct cells derived from a mouse model of Liddle's disease (β-ENaC truncation), it was found that EGF inhibited short-circuit current (Isc) by 24 ± 5% in wild-type cells but only by 6 ± 3% in homozygous mutant cells. In order to elucidate the role of specific regions of the β-ENaC C terminus, Madin-Darby canine kidney (MDCK) cell lines that express β-ENaC with mutation of the PY motif (P616L), the ERK phosphorylation site (T613A), and C terminus truncation (R564stop) were created using the Phoenix retroviral system. All three mutants exhibited significant attenuation of the EGF-induced inhibition of sodium current. In MDCK cells with wild-type β-ENaC, EGF-induced inhibition of Isc (<30 min) was fully reversed by exposure to an ERK kinase inhibitor and occurred with no change in ENaC surface expression, indicative of an effect on channel open probability (Po). At later times (>30 min), EGF-induced inhibition of Isc was not reversed by an ERK kinase inhibitor and was accompanied by a decrease in ENaC surface expression. Our results are consistent with an ERK-mediated decrease in ENaC open probability and enhanced retrieval of sodium channels from the apical membrane.

Endothelin-B Receptors Play an Important Role in Modulating Chronic Pressure-Natriuresis and Blood Pressure Regulation in Response to Changes in Dietary Sodium Intake.

Hypertension ◽  
2000 ◽  
Vol 36 (suppl_1) ◽  
pp. 682-682
Author(s):  
Joey P Granger ◽  
Kathy L Cockrell ◽  
Anna N Rinewalt ◽  
Barbara T Alexander
Keyword(s):  
Blood Pressure ◽  
Arterial Pressure ◽  
Urinary Excretion ◽  
Receptor Antagonist ◽  
Sodium Intake ◽  
Blood Pressure Regulation ◽  
Pressure Regulation ◽  
Endothelin System ◽  
Etb Receptor ◽  
Pressure Natriuresis

25 Activation of the ET B receptor by endothelin (ET-1) has been shown to inhibit renal tubule transport, dilate renal microcirculatory vessels, and inhibit renin release. The purpose of this study was to determine the role of ET and ET B receptors in modulating renal-pressure natriuresis and blood pressure regulation in response to changes in dietary Na intake. To test whether the renal production of ET is enhanced in response to elevation in Na intake, the effects of a low (0.4%), normal (1.0%), or high (8%) Na diet on 24hr urinary excretion of ET-1 and mRNA expression of preproendothelin (ribonuclease protection assay) were determined. Increasing Na intake from low to normal levels had no effect on urinary ET-1 excretion or renal expression of preproendothelin. In contrast, increasing Na intake from normal to high levels resulted in significant increases in urinary excretion of ET-1 (7223±968 vs 2127±167 pg/24hrs) and expression of preproendothelin (42.3±6.7 vs 25.4±1.8 densitometric units) in the renal medulla. To test whether ET B receptors play an important role in modulating arterial pressure in response to changes in Na intake, the relationship between arterial pressure and sodium excretion was determined in control rats and in ETB receptor antagonist-treated rats (A-192621, 30mg/kg/day for 7 days). Long-term ET B receptor blockade resulted in a significant rightward shift in the chronic pressure-natriuresis relationship. In control rats on a normal and high Na intake, AP was 122±3 and 132±3mmHg, respectively. In contrast, AP in ETB receptor antagonist-treated rats on a normal and high Na intake was 144±2 and 171±12mmHg, respectively. In summary, we report that the renal endothelin system is upregulated in response to increases in sodium intake. Blockade of the ET B receptors results in significant hypertension that is salt-sensitive. These results indicate that endothelin via ET B receptors plays an important role in modulating renal-pressure natriuresis and blood pressure regulation in response to changes in dietary Na intake.

Collecting duct-specific knockout of the endothelin B receptor causes hypertension and sodium retention

2006 ◽  
Vol 291 (6) ◽  
pp. F1274-F1280 ◽  
Author(s):  
Yuqiang Ge ◽  
Alan Bagnall ◽  
Peter K. Stricklett ◽  
Kevin Strait ◽  
David J. Webb ◽  
...  
Keyword(s):  
Collecting Duct ◽  
Receptor Gene ◽  
Plasma Renin ◽  
High Salt ◽  
Paracrine Effects ◽  
High Sodium ◽  
Eta Receptor ◽  
Etb Receptor ◽  
Endothelin B

Collecting duct (CD)-derived endothelin-1 (ET-1) inhibits renal Na reabsorption and its deficiency increases blood pressure (BP). The role of CD endothelin B (ETB) receptors in mediating these effects is unknown. CD-specific knockout of the ETB receptor was achieved using an aquaporin-2 promoter-Cre recombinase transgene and the loxP-flanked ETB receptor gene (CD ETB KO). Systolic BP in mice with CD-specific knockout of the ETB receptor, ETA receptor (CD ETA KO) and ET-1 (CD ET-1 KO), and their respective controls were compared during normal- and high-salt diet. On a normal-sodium diet, CD ETB KO mice had elevated BP, which increased further during high salt feeding. However, the degree of hypertension in CD ETB KO mice and the further increase in BP during salt feeding were lower than that of CD ET-1 KO mice, whereas CD ETA KO mice were normotensive. CD ETB KO mice had impaired sodium excretion following acute sodium loading. Aldosterone and plasma renin activity were decreased in CD ETB KO mice on normal- and high-sodium diets, while plasma and urinary ET-1 levels did not differ from controls. In conclusion, the CD ETB receptor partially mediates the antihypertensive and natriuretic effects of ET-1. CD ETA and ETB receptors do not fully account for the antihypertensive and natriuretic effects of CD-derived ET-1, suggesting paracrine effects of this peptide.

scholarly journals A role for the circadian clock protein Per1 in the regulation of aldosterone levels and renal Na+ retention

2013 ◽  
Vol 305 (12) ◽  
pp. F1697-F1704 ◽  
Author(s):  
Jacob Richards ◽  
Kit-Yan Cheng ◽  
Sean All ◽  
George Skopis ◽  
Lauren Jeffers ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Circadian Clock ◽  
Target Genes ◽  
Collecting Duct ◽  
Specific Rate ◽  
Wild Type ◽  
Α Subunit ◽  
Aldosterone Production

The circadian clock plays an important role in the regulation of physiological processes, including renal function and blood pressure. We have previously shown that the circadian protein period (Per)1 regulates the expression of multiple Na+ transport genes in the collecting duct, including the α-subunit of the renal epithelial Na+ channel. Consistent with this finding, Per1 knockout mice exhibit dramatically lower blood pressure than wild-type mice. We have also recently demonstrated the potential opposing actions of cryptochrome (Cry)2 on Per1 target genes. Recent work by others has demonstrated that Cry1/2 regulates aldosterone production through increased expression of the adrenal gland-specific rate-limiting enzyme 3β-dehydrogenase isomerase (3β-HSD). Therefore, we tested the hypothesis that Per1 plays a role in the regulation of aldosterone levels and renal Na+ retention. Using RNA silencing and pharmacological blockade of Per1 nuclear entry in the NCI-H295R human adrenal cell line, we showed that Per1 regulates 3β-HSD expression in vitro. These results were confirmed in vivo: mice with reduced levels of Per1 had decreased levels of plasma aldosterone and decreased mRNA expression of 3β-HSD. We postulated that mice with reduced Per1 would have a renal Na+-retaining defect. Indeed, metabolic cage experiments demonstrated that Per1 heterozygotes excreted more urinary Na+ compared with wild-type mice. Taken together, these data support the hypothesis that Per1 regulates aldosterone levels and that Per1 plays an integral role in the regulation of Na+ retention.

scholarly journals Reduced ENaC activity and blood pressure in mice with genetic knockout of the insulin receptor in the renal collecting duct

2013 ◽  
Vol 304 (3) ◽  
pp. F279-F288 ◽  
Author(s):  
Lijun Li ◽  
R. Mayuri Garikepati ◽  
Susanna Tsukerman ◽  
Donald Kohan ◽  
James B. Wade ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Insulin Receptor ◽  
Insulin Infusion ◽  
Collecting Duct ◽  
Wild Type ◽  
Low Sodium ◽  
Electrolyte Homeostasis ◽  
Urine Potassium ◽  
Epithelial Sodium Channel Enac

To elucidate the role of the insulin receptor (IR) in collecting duct (CD), we bred mice with IR selectively deleted from CD principal cells using an aquaporin-2 promoter to drive Cre-recombinase expression. Young, adult male knockout (KO) mice had altered plasma and electrolyte homeostasis under high- (HS) and low-sodium (LS) diets, relative to wild-type (WT) littermates. One week of LS feeding led to a significant reduction in urine potassium (K+) and sodium (Na+) excretion in KO, and a reduction in the ratio of Na+ to chloride (Cl−) in plasma, relative to WT. HS diet (1 wk) increased plasma K+ and reduced urine Na+ to Cl− ratio in the KO. Furthermore, KO mice had a significantly ( P = 0.025) blunted natriuretic response to benzamil, an epithelial sodium channel (ENaC) antagonist. Western blotting of cortex homogenates revealed modestly, but significantly (∼15%), lower band density for the β-subunit of ENaC in the KO vs. WT mice, with no differences for the α- or γ-subunits. Moreover, blood pressure (BP), measured by radiotelemetry, was significantly lower in KO vs. WT mice under basal conditions (mmHg): 112 ± 5 (WT), 104 ± 2 (KO), P = 0.023. Chronic insulin infusion reduced heart rate in the WT, but not in the KO, and modestly reduced BP in the WT only. Overall, these results support a fundamental role for insulin through its classic receptor in the modulation of electrolyte homeostasis and BP.

Elevation of blood pressure by genetic and pharmacological disruption of the ETB receptor in mice

1999 ◽  
Vol 276 (4) ◽  
pp. R1071-R1077 ◽  
Author(s):  
Takashi Ohuchi ◽  
Tomoyuki Kuwaki ◽  
Guang-Yi Ling ◽  
Damiane Dewit ◽  
Ki-Hwan Ju ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Pressor Response ◽  
Inbred Mice ◽  
Respiratory Control ◽  
Wild Type ◽  
Targeted Disruption ◽  
Arterial Blood ◽  
Respiratory Parameters ◽  
Etb Receptor ◽  
Depressor Effect

Exogenously administered endothelin (ET) elicits both pressor and depressor responses through the ETA and/or the ETB receptor on vascular smooth muscle cells and ETB on endothelial cells. To test whether ETB has pressor or depressor effects under basal physiological conditions, we determined arterial blood pressure (BP) in ETB-deficient mice obtained by crossing inbred mice heterozygous for targeted disruption of the ETB gene with mice homozygous for the piebald ( s) mutation of the ETB gene ( ET B s/s ). F1 ET B −/s and ET B +/s progeny share an identical genetic background but have ETB levels that are ∼[Formula: see text]and [Formula: see text], respectively, of wild-type mice ( ET B +/+ ). BP in ET B −/s mice was significantly higher, by ∼20 mmHg, than that in ET B +/s or ET B +/+ mice. Immunoreactive ET-1 concentration in plasma as well as respiratory parameters was not different between ET B −/s and ET B +/s mice. A selective ETB antagonist, BQ-788, increased BP in ET B +/s and ET B +/+ but not in ET B −/s mice. Pretreatment with indomethacin, but not with N G-monomethyl-l-arginine, can attenuate the observed pressor response to BQ-788. The selective ETA antagonist BQ-123 did not ameliorate the increased BP in ET B −/s mice. Moreover, BP in mice heterozygous for targeted disruption of the ETA gene was not different from that in wild-type controls. These results suggest that endogenous ET elicits a depressor effect through ETB under basal conditions, in part through tonic production of prostaglandins, and not through secondary mechanisms involving respiratory control or clearance of circulating ET.

scholarly journals Combined knockout of collecting duct endothelin A and B receptors causes hypertension and sodium retention

2008 ◽  
Vol 295 (6) ◽  
pp. F1635-F1640 ◽  
Author(s):  
Yuqiang Ge ◽  
Alan Bagnall ◽  
Peter K. Stricklett ◽  
David Webb ◽  
Yuri Kotelevtsev ◽  
...  
Keyword(s):  
Salt Intake ◽  
Collecting Duct ◽  
Plasma Renin ◽  
Hypotensive Effect ◽  
Sodium Retention ◽  
High Salt Intake ◽  
Eta Receptor ◽  
Etb Receptor ◽  
Endothelin A ◽  
Salt Sensitive Hypertension

The collecting duct (CD) endothelin (ET) system regulates blood pressure (BP) and Na excretion. CD-specific knockout (KO) of ET-1 causes hypertension, CD-specific KO of the ETA receptor does not alter BP, while CD-specific KO of the ETB receptor increases BP to a lesser extent than CD ET-1 KO. These findings suggest a paracrine role for CD-derived ET-1; however, they do not exclude compensation for the loss of one ET receptor by the other. To examine this, mice with CD-specific KO of both ETA and ETB receptors were generated (CD ETA/B KO). CD ETA/B KO mice excreted less urinary Na than controls during acute or chronic Na loading. Urinary aldosterone excretion and plasma renin concentration were similar during Na intake and both fell comparably during Na loading. On a normal sodium diet, CD ETA/B KO mice had increased BP, which increased further with high salt intake. The degree of BP elevation during normal Na intake was similar to CD ET-1 KO mice and higher than CD ETB KO animals. During 1 wk of Na loading, CD ETA/B KO mice had higher BPs than CD ETB KO, while BP was less than CD ET-1 KOs until the latter days of Na loading. These studies suggest that 1) CD ETA/B deficiency causes salt-sensitive hypertension, 2) CD ETA/B KO-associated Na retention is associated with failure to suppress the renin-angiotensin-aldosterone system, and 3) CD ETA and ETB receptors exerts a combined hypotensive effect that exceeds that of either receptor alone.

scholarly journals Regulation of the epithelial Na+ channel by endothelin-1 in rat collecting duct

2008 ◽  
Vol 295 (4) ◽  
pp. F1063-F1070 ◽  
Author(s):  
Vladislav Bugaj ◽  
Oleh Pochynyuk ◽  
Elena Mironova ◽  
Alain Vandewalle ◽  
Jorge L. Medina ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Na Channel ◽  
Open Probability ◽  
Endothelin 1 ◽  
Principal Cells ◽  
Patch Clamp Electrophysiology ◽  
Src Family Tyrosine Kinases

We used patch-clamp electrophysiology to investigate regulation of the epithelial Na+ channel (ENaC) by endothelin-1 (ET-1) in isolated, split-open rat collecting ducts. ET-1 significantly decreases ENaC open probability by about threefold within 5 min. ET-1 decreases ENaC activity through basolateral membrane ETB but not ETA receptors. In rat collecting duct, we find no role for phospholipase C or protein kinase C in the rapid response of ENaC to ET-1. ET-1, although, does activate src family tyrosine kinases and their downstream MAPK1/2 effector cascade in renal principal cells. Both src kinases and MAPK1/2 signaling are necessary for ET-1-dependent decreases in ENaC open probability in the split-open collecting duct. We conclude that ET-1 in a physiologically relevant manner rapidly suppresses ENaC activity in native, mammalian principal cells. These findings may provide a potential mechanism for the natriuresis observed in vivo in response to ET-1, as well as a potential cause for the salt-sensitive hypertension found in animals with impaired endothelin signaling.

Chronic increases in blood flow upregulate endothelin-B receptors in arterial smooth muscle

1996 ◽  
Vol 270 (1) ◽  
pp. H65-H71 ◽  
Author(s):  
D. A. Barber ◽  
S. R. Michener ◽  
S. C. Ziesmer ◽  
V. M. Miller
Keyword(s):  
Blood Flow ◽  
Smooth Muscle ◽  
Membrane Proteins ◽  
Isometric Force ◽  
Endothelin Receptors ◽  
Binding Studies ◽  
Arterial Smooth Muscle ◽  
Endothelin 1 ◽  
Etb Receptor ◽  
Endothelin B

Experiments were designed to characterize endothelin receptors in arteries after chronic increases in blood flow. A fistula was created between the femoral artery and vein in one hindlimb of dogs; contralateral blood vessels were sham operated. Sham- and fistula-operated arteries were removed 6 wk postoperatively. Some arteries were prepared for measurement of isometric force or for isolation of membrane proteins. Other arteries were used for histological staining with an endothelin-B (ETB) receptor antibody. In arteries suspended for the measurement of isometric force, endothelin-1 produced concentration-dependent increases in tension that were significantly greater in fistula- than in sham-operated arteries without endothelium. The ETB-receptor-selective peptide sarafotoxin S6c produced concentration-dependent increases in tension only in fistula-operated arteries. In receptor-binding studies of membrane proteins, Scatchard analysis of saturation binding with 125I-labeled endothelin-1 (125I-endothelin-1) indicated that the total number of receptors was greater in fistula-operated arteries; affinity was threefold less in fistula- than in sham-operated arteries. Competitive displacement of 125I-endothelin-1 by endothelin-3 was significant for a two-site model in membranes prepared from sham-and fistula-operated arteries. Competitive inhibition of 125I-endothelin-1 binding by sarafotoxin S6c was significant for a one-site binding model in all arteries. Sarafotoxin S6c binding sites were elevated significantly in fistula-operated arteries. Immunohistochemical staining for the ETB receptor was significantly greater in both the endothelium and smooth muscle of fistula- than in sham-operated arteries. These results suggest that chronic increases in blood flow upregulate endothelin receptors, including ETB receptors in arterial smooth muscle.

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