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Kim K, Nist KM, Puleo F, McKenna J, Wainford RD. Sex differences in dietary sodium evoked NCC regulation and blood pressure in male and female Sprague-Dawley, Dahl salt-resistant, and Dahl salt-sensitive rats. Am J Physiol Renal Physiol 2024; 327:F277-F289. [PMID: 38813592 DOI: 10.1152/ajprenal.00150.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 05/07/2024] [Accepted: 05/15/2024] [Indexed: 05/31/2024] Open
Abstract
Hypertension affects approximately one in two United States adults and sex plays an important role in the pathogenesis of hypertension. The Na+-Cl- cotransporter (NCC), regulated by a kinase network including with-no-lysine kinase (WNK)1 and WNK4, STE20/SPS1-related proline alanine-rich kinase (SPAK), and oxidative stress response 1 (OxSR1), is critical to Na+ reabsorption and blood pressure regulation. Dietary salt differentially modulates NCC in salt-sensitive and salt-resistant rats, in part by modulation of WNK/SPAK/OxSR1 signaling. In this study, we tested the hypothesis that sex-dependent differences in NCC regulation contribute to the development of the salt sensitivity of blood pressure using male and female Sprague-Dawley (SD), Dahl salt-resistant (DSR), and Dahl salt-sensitive (DSS) rats. In normotensive salt-resistant SD and DSR rats, a high-salt diet evoked significant decreases in NCC activity, expression, and phosphorylation. In males, these changes were associated with no change in WNK1 expression, a decrease in WNK4 levels, and suppression of SPAK/OxSR1 expression and phosphorylation. In contrast, in females, there was decreased NCC activity associated with suppression of SPAK/OxSR1 expression and phosphorylation. In hypertensive DSS rats, the ability of females to suppress NCC (in opposition to males) via a SPAK/OxSR1 mechanism likely contributes to their lower magnitude of salt-sensitive hypertension. Collectively, our findings support the existence of sex differences in male versus female rats with NCC regulation during dietary salt intake involving suppression of WNK4 expression in male rats only and the involvement of SPAK/OxSR1 signaling in both males and females.NEW & NOTEWORTHY NCC regulation is sex dependent. In normotensive male and female Sprague-Dawley and Dahl salt-resistant rats, which exhibit dietary Na+-evoked NCC suppression, male rats exhibit decreased WNK4 expression and decreased SPAK and OxSR1 levels, whereas female rats only suppress SPAK and OxSR1. In hypertensive Dahl salt-sensitive rats, the ability of females to suppress NCC (in opposition to males) via a SPAK/OxSR1 mechanism likely contributes to their lower magnitude of salt-sensitive hypertension.
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Affiliation(s)
- Kiyoung Kim
- Department of Pharmacology and Experimental Therapeutics, Whitaker Cardiovascular Institute, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts, United States
| | - Kayla M Nist
- Department of Anatomy and Neurobiology, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts, United States
| | - Franco Puleo
- Department of Pharmacology and Experimental Therapeutics, Whitaker Cardiovascular Institute, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts, United States
| | - James McKenna
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Richard D Wainford
- Department of Pharmacology and Experimental Therapeutics, Whitaker Cardiovascular Institute, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts, United States
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
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Frame AA, Nist KM, Kim K, Puleo F, Moreira JD, Swaldi H, McKenna J, Wainford RD. Integrated renal and sympathetic mechanisms underlying the development of sex- and age-dependent hypertension and the salt sensitivity of blood pressure. GeroScience 2024:10.1007/s11357-024-01266-1. [PMID: 38976131 DOI: 10.1007/s11357-024-01266-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Accepted: 06/25/2024] [Indexed: 07/09/2024] Open
Abstract
Aging is a non-modifiable understudied risk factor for hypertension. We hypothesized that sympathetically mediated activation of renal sodium reabsorption drives age-dependent hypertension and the salt sensitivity of blood pressure (BP). Using 3-, 8-, and 16-month-old male and female Sprague-Dawley rats as a model of normal aging, we assessed BP, indices of sympathetic tone, and the physiological responses to acute and chronic sodium challenge including sodium chloride cotransporter (NCC) regulation. The effects of renal nerve ablation and NCC antagonism were assessed in hypertensive male rats. We observed sex-dependent impaired renal sodium handling (24 h sodium balance (meq), male 3-month 0.36 ± 0.1 vs. 16-month 0.84 ± 0.2; sodium load excreted during 5% bodyweight isotonic saline volume expansion (%) male 3-month 77 ± 5 vs. 16-month 22 ± 8), hypertension (MAP (mmHg) male 3-month 123 ± 4 vs. 16-month 148 ± 6), and the salt sensitivity of BP in aged male, but not female, rats. Attenuated sympathoinhibitory afferent renal nerve (ARN) responses contributed to increased sympathetic tone and hypertension in male rats. Increased sympathetic tone contributes to renal sodium retention, in part through increased NCC activity via a dysfunctional with-no-lysine kinase-(WNK) STE20/SPS1-related proline/alanine-rich kinase signaling pathway, to drive hypertension and the salt sensitivity of BP in aged male rats. NCC antagonism and renal nerve ablation, which reduced WNK dysfunction and decreased NCC activity, attenuated age-dependent hypertension in male Sprague-Dawley rats. The contribution of an impaired sympathoinhibitory ARN reflex to sex- and age-dependent hypertension in an NCC-dependent manner, via an impaired WNK1/WNK4 dynamic, suggests this pathway as a mechanism-based target for the treatment of age-dependent hypertension.
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Affiliation(s)
- Alissa A Frame
- Department of Pharmacology & Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, USA
| | - Kayla M Nist
- Department of Anatomy & Neurobiology, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, USA
| | - Kiyoung Kim
- Department of Pharmacology & Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, USA
| | - Franco Puleo
- Department of Pharmacology & Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, USA
| | - Jesse D Moreira
- Department of Health Sciences, Sargent College, Boston University, Boston, MA, USA
| | - Hailey Swaldi
- Division of Cardiology, Emory University School of Medicine, 1750 Haygood Drive, Atlanta, GA, N22030322, USA
| | - James McKenna
- Division of Cardiology, Emory University School of Medicine, 1750 Haygood Drive, Atlanta, GA, N22030322, USA
| | - Richard D Wainford
- Department of Pharmacology & Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, USA.
- Division of Cardiology, Emory University School of Medicine, 1750 Haygood Drive, Atlanta, GA, N22030322, USA.
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Buncha V, Cherezova A, Alexander S, Baranovskaya I, Coleman KA, Cherian-Shaw M, Brands MW, Sullivan JC, O'Connor PM, Mamenko M. Aldosterone Antagonism Is More Effective at Reducing Blood Pressure and Excessive Renal ENaC Activity in AngII-Infused Female Rats Than in Males. Hypertension 2023; 80:2196-2208. [PMID: 37593894 PMCID: PMC10528186 DOI: 10.1161/hypertensionaha.123.21287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 08/03/2023] [Indexed: 08/19/2023]
Abstract
BACKGROUND AngII (angiotensin II)-dependent hypertension causes comparable elevations of blood pressure (BP), aldosterone levels, and renal ENaC (epithelial Na+ channel) activity in male and female rodents. Mineralocorticoid receptor (MR) antagonism has a limited antihypertensive effect associated with insufficient suppression of renal ENaC in male rodents with AngII-hypertension. While MR blockade effectively reduces BP in female mice with salt-sensitive and leptin-induced hypertension, MR antagonism has not been studied in female rodents with AngII-hypertension. We hypothesize that overstimulation of renal MR signaling drives redundant ENaC-mediated Na+ reabsorption and BP increase in female rats with AngII-hypertension. METHODS We employ a combination of physiological, pharmacological, biochemical, and biophysical approaches to compare the effect of MR inhibitors on BP and ENaC activity in AngII-infused male and female Sprague Dawley rats. RESULTS MR blockade markedly attenuates AngII-hypertension in female rats but has only a marginal effect in males. Spironolactone increases urinary sodium excretion and urinary sodium-to-potassium ratio in AngII-infused female, but not male, rats. The expression of renal MR and HSD11β2 (11β-hydroxysteroid dehydrogenase type 2) that determines the availability of MR to aldosterone is significantly higher in AngII-infused female rats than in males. ENaC activity is ≈2× lower in spironolactone-treated AngII-infused female rats than in males. Reduced ENaC activity in AngII-infused female rats on spironolactone correlates with increased interaction with ubiquitin ligase Nedd4-2 (neural precursor cell expressed developmentally down-regulated protein 4-2), targeting ENaC for degradation. CONCLUSIONS MR-ENaC axis is the primary determinant of excessive renal sodium reabsorption and an attractive antihypertensive target in female rats with AngII-hypertension, but not in males.
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Affiliation(s)
- Vadym Buncha
- Department of Physiology, Medical College of Georgia, Augusta University
| | - Alena Cherezova
- Department of Physiology, Medical College of Georgia, Augusta University
| | - Sati Alexander
- Department of Physiology, Medical College of Georgia, Augusta University
| | - Irina Baranovskaya
- Department of Physiology, Medical College of Georgia, Augusta University
| | - Kathleen A Coleman
- Department of Physiology, Medical College of Georgia, Augusta University
| | - Mary Cherian-Shaw
- Department of Physiology, Medical College of Georgia, Augusta University
| | - Michael W Brands
- Department of Physiology, Medical College of Georgia, Augusta University
| | | | - Paul M O'Connor
- Department of Physiology, Medical College of Georgia, Augusta University
| | - Mykola Mamenko
- Department of Physiology, Medical College of Georgia, Augusta University
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Sutovska H, Molcan L, Majzunova M, Sykora M, Kopkan L, Zeman M. Mineralocorticoid receptor blockade protects the kidneys but does not affect inverted blood pressure rhythm in hypertensive transgenic (mRen-2)27 rats. Mol Cell Endocrinol 2023; 572:111967. [PMID: 37210027 DOI: 10.1016/j.mce.2023.111967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/17/2023] [Accepted: 05/17/2023] [Indexed: 05/22/2023]
Abstract
Aldosterone regulates blood pressure (BP) through water and sodium balance. In our study, we studied if continuous treatment with a mineralocorticoid receptor antagonist, spironolactone (30 mg/kg/day) for 20 days can: 1) attenuate hypertension development and restore inverted 24-h BP rhythm in hypertensive transgenic (mRen-2)27 rats (TGR) measured by telemetry; 2) improve function of the kidneys and heart; 3) be protective against high salt load (1% in water) by mitigating oxidative injury and improving kidney function. Spironolactone decreased albuminuria and 8-isoprostane in normal and salt load conditions in BP-independent effects. Salt load increased BP, impaired autonomic balance, suppressed plasma aldosterone level and increased natriuresis, albuminuria and oxidative injury in TGR. Spironolactone did not restore the inverted 24-h rhythm of BP in TGR, therefore, mineralocorticoids are not crucial in regulation of BP daily profile. Spironolactone improved kidney function, decreased oxidative stress and was protective against high salt load in the BP-independent manner.
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Affiliation(s)
- Hana Sutovska
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
| | - Lubos Molcan
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
| | - Miroslava Majzunova
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
| | - Matus Sykora
- Centre of Experimental Medicine, Institute for Heart Research, Slovak Academy of Sciences, Bratislava, Slovak Republic.
| | - Libor Kopkan
- Institute for Clinical and Experimental Medicine, Prague, Czech Republic.
| | - Michal Zeman
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
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Management of edema in pediatric nephrotic syndrome – Underfill or overfill? CURRENT PEDIATRICS REPORTS 2022. [DOI: 10.1007/s40124-022-00270-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Leader CJ, Wilkins GT, Walker RJ. The effect of spironolactone on cardiac and renal fibrosis following myocardial infarction in established hypertension in the transgenic Cyp1a1Ren2 rat. PLoS One 2021; 16:e0260554. [PMID: 34843581 PMCID: PMC8629264 DOI: 10.1371/journal.pone.0260554] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 11/11/2021] [Indexed: 11/19/2022] Open
Abstract
AIMS The renin-angiotensin-aldosterone axis plays a key role in mediating cardiac and kidney injury. Mineralocorticoid receptor antagonism has beneficial effects on cardiac dysfunction, but effects are less well quantified in the cardiorenal syndrome. This study investigated cardiac and kidney pathophysiology following permanent surgical ligation to induce myocardial infarction (MI) in hypertensive animals with or without mineralocorticoid receptor antagonism. METHODS Hypertension was induced in adult male Cyp1a1Ren2 rats. Hypertensive animals underwent MI surgery (n = 6), and were then treated daily with spironolactone for 28 days with serial systolic blood pressure measurements, echocardiograms and collection of urine and serum biochemical data. They were compared to hypertensive animals (n = 4), hypertensive animals treated with spironolactone (n = 4), and hypertensive plus MI without spironolactone (n = 6). Cardiac and kidney tissue was examined for histological and immunohistochemical analysis. RESULTS MI superimposed on hypertension resulted in an increase in interstitial cardiac fibrosis (p<0.001), renal cortical interstitial fibrosis (p<0.01) and glomerulosclerosis (p<0.01). Increased fibrosis was accompanied by myofibroblast and macrophage infiltration in the heart and the kidney. Spironolactone post-MI, diminished the progressive fibrosis (p<0.001) and inflammation (myofibroblasts (p<0.05); macrophages (p<0.01)) in both the heart and the kidney, despite persistently elevated SBP (182±19 mmHg). Despite the reduction in inflammation and fibrosis, spironolactone did not modify ejection fraction, proteinuria, or renal function when compared to untreated animals post MI. CONCLUSION This model of progressive cardiorenal dysfunction more closely replicates the clinical setting. Mineralocorticoid receptor blockade at a clinically relevant dose, blunted progression of cardiac and kidney fibrosis with reduction in cardiac and kidney inflammatory myofibroblast and macrophage infiltration. Further studies are underway to investigate the combined actions of angiotensin blockade with mineralocorticoid receptor blockade.
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Affiliation(s)
- C. J. Leader
- Department of Medicine, University of Otago, Dunedin, New Zealand
| | - G. T. Wilkins
- Department of Medicine, University of Otago, Dunedin, New Zealand
| | - R. J. Walker
- Department of Medicine, University of Otago, Dunedin, New Zealand
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Puleo F, Kim K, Frame AA, Walsh KR, Ferdaus MZ, Moreira JD, Comsti E, Faudoa E, Nist KM, Abkin E, Wainford RD. Sympathetic Regulation of the NCC (Sodium Chloride Cotransporter) in Dahl Salt-Sensitive Hypertension. Hypertension 2020; 76:1461-1469. [PMID: 32981364 PMCID: PMC7727920 DOI: 10.1161/hypertensionaha.120.15928] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Increased sympathoexcitation and renal sodium retention during high salt intake are hallmarks of the salt sensitivity of blood pressure. The mechanism(s) by which excessive sympathetic nervous system release of norepinephrine influences renal sodium reabsorption is unclear. However, studies demonstrate that norepinephrine can stimulate the activity of the NCC (sodium chloride cotransporter) and promote the development of SSH (salt-sensitive hypertension). The adrenergic signaling pathways governing NCC activity remain a significant source of controversy with opposing studies suggesting a central role of upstream α1- and β-adrenoceptors in the canonical regulatory pathway involving WNKs (with-no-lysine kinases), SPAK (STE20/SPS1-related proline alanine-rich kinase), and OxSR1 (oxidative stress response 1). In our previous study, α1-adrenoceptor antagonism in norepinephrine-infused male Sprague-Dawley rats prevented the development of norepinephrine-evoked SSH in part by suppressing NCC activity and expression. In these studies, we used selective adrenoceptor antagonism in male Dahl salt-sensitive rats to test the hypothesis that norepinephrine-mediated activation of the NCC in Dahl SSH occurs via an α1-adrenoceptor dependent pathway. A high-salt diet evoked significant increases in NCC activity, expression, and phosphorylation in Dahl salt-sensitive rats that developed SSH. Increases were associated with a dysfunctional WNK1/4 dynamic and a failure to suppress SPAK/OxSR1 activity. α1-adrenoceptor antagonism initiated before high-salt intake or following the establishment of SSH attenuated blood pressure in part by suppressing NCC activity, expression, and phosphorylation. Collectively, our findings support the existence of a norepinephrine-activated α1-adrenoceptor gated pathway that relies on WNK/SPAK/OxSR1 signaling to regulate NCC activity in SSH.
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Affiliation(s)
- Franco Puleo
- Department of Pharmacology & Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
| | - Kiyoung Kim
- Department of Pharmacology & Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
| | - Alissa A. Frame
- Department of Pharmacology & Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
| | - Kathryn R. Walsh
- Department of Pharmacology & Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
| | - Mohammed Z. Ferdaus
- Department of Pharmacology & Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
| | - Jesse D. Moreira
- Department of Health Sciences, Sargent College, Boston University, Boston, Massachusetts
| | - Erica Comsti
- Department of Health Sciences, Sargent College, Boston University, Boston, Massachusetts
| | - Elizabeth Faudoa
- College of Arts and Sciences, Boston University, Boston, Massachusetts
| | - Kayla M. Nist
- Department of Anatomy & Neurobiology, Boston University School of Medicine, Boston, Massachusetts
| | - Eric Abkin
- Department of Health Sciences, Sargent College, Boston University, Boston, Massachusetts
| | - Richard D. Wainford
- Department of Pharmacology & Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
- Department of Health Sciences, Sargent College, Boston University, Boston, Massachusetts
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Veiras LC, McFarlin BE, Ralph DL, Buncha V, Prescott J, Shirvani BS, McDonough JC, Ha D, Giani J, Gurley SB, Mamenko M, McDonough AA. Electrolyte and transporter responses to angiotensin II induced hypertension in female and male rats and mice. Acta Physiol (Oxf) 2020; 229:e13448. [PMID: 31994810 DOI: 10.1111/apha.13448] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 01/21/2020] [Accepted: 01/23/2020] [Indexed: 12/15/2022]
Abstract
AIM Sexual dimorphisms are evident along the nephron: Females (F) exhibit higher ratios of renal distal to proximal Na+ transporters' abundance, greater lithium clearance (CLi ) more rapid natriuresis in response to saline infusion and lower plasma [K+ ] vs. males (M). During angiotensin II infusion hypertension (AngII-HTN) M exhibit distal Na+ transporter activation, lower proximal and medullary loop transporters, blunted natriuresis in response to saline load, and reduced plasma [K+ ]. This study aimed to determine whether responses of F to AngII-HTN mimicked those in M or were impacted by sexual dimorphisms evident at baseline. METHODS Sprague Dawley rats and C57BL/6 mice were AngII infused via osmotic minipumps 2 and 3 weeks, respectively, and assessed by metabolic cage collections, tail-cuff sphygmomanometer, semi-quantitative immunoblotting of kidney and patch-clamp electrophysiology. RESULTS In F rats, AngII-infusion increased BP to 190 mm Hg, increased phosphorylation of cortical NKCC2, NCC and cleavage of ENaC two to threefold, increased ENaC channel activity threefold and aldosterone 10-fold. K+ excretion increased and plasma [K+ ] decreased. Evidence of natriuresis in F included increased urine Na+ excretion and CLi , and decreased medullary NHE3, NKCC2 and Na,K-ATPase abundance. In C57BL/6 mice, AngII-HTN increased abundance of distal Na+ transporters, suppressed proximal-medullary transporters and reduced plasma [K+ ] in both F and M. CONCLUSION Despite baseline sexual dimorphisms, AngII-HTN provokes similar increases in BP, aldosterone, distal transporters, ENaC channel activation and K+ loss accompanied by similar suppression of proximal and loop Na+ transporters, natriuresis and diuresis in females and males.
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Affiliation(s)
- Luciana C. Veiras
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
- Department of Biomedical Sciences Cedars‐Sinai Medical Center Los Angeles CA USA
| | - Brandon E. McFarlin
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
| | - Donna L. Ralph
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
| | - Vadym Buncha
- Department of Physiology Medical College of Georgia at Augusta University Augusta GA USA
| | - Jessica Prescott
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
| | - Borna S. Shirvani
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
| | - Jillian C. McDonough
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
| | - Darren Ha
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
| | - Jorge Giani
- Department of Biomedical Sciences Cedars‐Sinai Medical Center Los Angeles CA USA
| | - Susan B. Gurley
- Division of Nephrology and Hypertension Oregon Health and Science University Portland OR USA
| | - Mykola Mamenko
- Department of Physiology Medical College of Georgia at Augusta University Augusta GA USA
| | - Alicia A. McDonough
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
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Leader CJ, Kelly DJ, Sammut IA, Wilkins GT, Walker RJ. Spironolactone mitigates, but does not reverse, the progression of renal fibrosis in a transgenic hypertensive rat. Physiol Rep 2020; 8:e14448. [PMID: 32441493 PMCID: PMC7243196 DOI: 10.14814/phy2.14448] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/15/2020] [Accepted: 04/24/2020] [Indexed: 01/10/2023] Open
Abstract
Hypertension plays an important role in the development and progression of chronic kidney disease. Studies to date, with mineralocorticoid receptor antagonists (MRA), have demonstrated varying degrees of results in modifying the development of renal fibrosis. This study aimed to investigate whether treatment with a MRA commenced following the establishment of hypertension, a situation more accurately representing the clinical setting, modified the progression of renal fibrosis. Using male Cyp1a1Ren2 rats (n = 28), hypertension was established by addition of 0.167% indole-3-carbinol (w/w) to the rat chow, for 2 weeks prior to treatment. Rats were then divided into normotensive, hypertensive (H), or hypertensive with daily oral spironolactone treatment (H + SP) (human equivalent dose 50 mg/day). Physiological data and tissue were collected after 4 and 12 weeks for analysis. After 4 weeks, spironolactone had no demonstrable effect on systolic blood pressure (SBP), proteinuria, or macrophage infiltration in the renal cortex. However, glomerulosclerosis and renal cortical fibrosis were significantly decreased. Following 12 weeks of spironolactone treatment, SBP was lowered (not back to normotensive levels), proteinuria was reduced, and the progression of glomerulosclerosis and renal cortical fibrosis was significantly blunted. This was associated with a significant reduction in macrophage and myofibroblast infiltration, as well as CTGF and pSMAD2 expression. In summary, in a model of established hypertension, spironolactone significantly blunted the progression of renal fibrosis and glomerulosclerosis, and downregulated the renal inflammatory response, which was associated with reduced proteinuria, despite only a partial reduction in systolic blood pressure. This suggests a blood pressure independent effect of MRA on renal fibrosis.
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Affiliation(s)
| | - Darren J. Kelly
- Department of MedicineUniversity of MelbourneMelbourneVICAustralia
| | - Ivan A. Sammut
- Department of PharmacologyUniversity of OtagoDunedinNew Zealand
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Frame AA, Puleo F, Kim K, Walsh KR, Faudoa E, Hoover RS, Wainford RD. Sympathetic regulation of NCC in norepinephrine-evoked salt-sensitive hypertension in Sprague-Dawley rats. Am J Physiol Renal Physiol 2019; 317:F1623-F1636. [PMID: 31608673 DOI: 10.1152/ajprenal.00264.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Salt sensitivity of blood pressure is characterized by inappropriate sympathoexcitation and renal Na+ reabsorption during high salt intake. In salt-resistant animal models, exogenous norepinephrine (NE) infusion promotes salt-sensitive hypertension and prevents dietary Na+-evoked suppression of the Na+-Cl- cotransporter (NCC). Studies of the adrenergic signaling pathways that modulate NCC activity during NE infusion have yielded conflicting results implicating α1- and/or β-adrenoceptors and a downstream kinase network that phosphorylates and activates NCC, including with no lysine kinases (WNKs), STE20/SPS1-related proline-alanine-rich kinase (SPAK), and oxidative stress response 1 (OxSR1). In the present study, we used selective adrenoceptor antagonism in NE-infused male Sprague-Dawley rats to investigate the differential roles of α1- and β-adrenoceptors in sympathetically mediated NCC regulation. NE infusion evoked salt-sensitive hypertension and prevented dietary Na+-evoked suppression of NCC mRNA, protein expression, phosphorylation, and in vivo activity. Impaired NCC suppression during high salt intake in NE-infused rats was paralleled by impaired suppression of WNK1 and OxSR1 expression and SPAK/OxSR1 phosphorylation and a failure to increase WNK4 expression. Antagonism of α1-adrenoceptors before high salt intake or after the establishment of salt-sensitive hypertension restored dietary Na+-evoked suppression of NCC, resulted in downregulation of WNK4, SPAK, and OxSR1, and abolished the salt-sensitive component of hypertension. In contrast, β-adrenoceptor antagonism attenuated NE-evoked hypertension independently of dietary Na+ intake and did not restore high salt-evoked suppression of NCC. These findings suggest that a selective, reversible, α1-adenoceptor-gated WNK/SPAK/OxSR1 NE-activated signaling pathway prevents dietary Na+-evoked NCC suppression, promoting the development and maintenance of salt-sensitive hypertension.
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Affiliation(s)
- Alissa A Frame
- Department of Pharmacology and Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
| | - Franco Puleo
- Department of Pharmacology and Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
| | - Kiyoung Kim
- Department of Pharmacology and Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
| | - Kathryn R Walsh
- Department of Pharmacology and Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
| | - Elizabeth Faudoa
- College of Arts and Sciences, Boston University, Boston, Massachusetts
| | - Robert S Hoover
- Research Service, Atlanta Veterans Affairs Medical Center, Decatur, Georgia.,Division of Nephrology, Department of Medicine, Emory University, Atlanta, Georgia
| | - Richard D Wainford
- Department of Pharmacology and Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
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11
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Rapoport RM, Soleimani M. Mechanism of Thiazide Diuretic Arterial Pressure Reduction: The Search Continues. Front Pharmacol 2019; 10:815. [PMID: 31543812 PMCID: PMC6730501 DOI: 10.3389/fphar.2019.00815] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 06/24/2019] [Indexed: 12/21/2022] Open
Abstract
Thiazide diuretic (TZD)-mediated chronic reduction of arterial pressure is thought to occur through decreased total peripheral vascular resistance. Further, the decreased peripheral vascular resistance is accomplished through TZD activation of an extrarenal target, resulting in inhibition of vascular constriction. However, despite greater than five decades of investigation, little progress has been made into the identification of the TZD extrarenal target. Proposed mechanisms range from direct inhibition of constrictor and activation of relaxant signaling pathways in the vascular smooth muscle to indirect inhibition through decreased neurogenic and hormonal regulatory pathways. Surprisingly, particularly in view of this lack of progress, comprehensive reviews of the subject are absent. Moreover, even though it is well recognized that 1) several types of hypertension are insensitive to TZD reduction of arterial pressure and, further, TZD fail to reduce arterial pressure in normotensive subjects and animals, and 2) different mechanisms underlie acute and chronic TZD, findings derived from these models and parameters remain largely undifferentiated. This review 1) comprehensively describes findings associated with TZD reduction of arterial pressure; 2) differentiates between observations in TZD-sensitive and TZD-insensitive hypertension, normotensive subjects/animals, and acute and chronic effects of TZD; 3) critically evaluates proposed TZD extrarenal targets; 4) proposes guiding parameters for relevant investigations into extrarenal TZD target identification; and 5) proposes a working model for TZD chronic reduction of arterial pressure through vascular dilation.
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Affiliation(s)
- Robert M Rapoport
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Manoocher Soleimani
- Research Service, Veterans Affairs Medical Center, Cincinnati, OH, United States.,Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, United States
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12
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Angiotensin II-induced hypertension in rats is only transiently accompanied by lower renal oxygenation. Sci Rep 2018; 8:16342. [PMID: 30397212 PMCID: PMC6218546 DOI: 10.1038/s41598-018-34211-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 10/09/2018] [Indexed: 02/08/2023] Open
Abstract
Activation of the renin-angiotensin system may initiate chronic kidney disease. We hypothesised that renal hypoxia is a consequence of hemodynamic changes induced by angiotensin II and occurs prior to development of severe renal damage. Male Sprague-Dawley rats were infused continuously with angiotensin II (350 ng/kg/min) for 8 days. Mean arterial pressure (n = 5), cortical (n = 6) and medullary (n = 7) oxygenation (pO2) were continuously recorded by telemetry and renal tissue injury was scored. Angiotensin II increased arterial pressure gradually to 150 ± 18 mmHg. This was associated with transient reduction of oxygen levels in renal cortex (by 18 ± 2%) and medulla (by 17 ± 6%) at 10 ± 2 and 6 ± 1 hours, respectively after starting infusion. Thereafter oxygen levels normalised to pre-infusion levels and were maintained during the remainder of the infusion period. In rats receiving angiotensin II, adding losartan to drinking water (300 mg/L) only induced transient increase in renal oxygenation, despite normalisation of arterial pressure. In rats, renal hypoxia is only a transient phenomenon during initiation of angiotensin II-induced hypertension.
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13
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Ivy JR, Evans LC, Moorhouse R, Richardson RV, Al-Dujaili EAS, Flatman PW, Kenyon CJ, Chapman KE, Bailey MA. Renal and Blood Pressure Response to a High-Salt Diet in Mice With Reduced Global Expression of the Glucocorticoid Receptor. Front Physiol 2018; 9:848. [PMID: 30038578 PMCID: PMC6046455 DOI: 10.3389/fphys.2018.00848] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 06/14/2018] [Indexed: 01/02/2023] Open
Abstract
Salt-sensitive hypertension is common in glucocorticoid excess. Glucocorticoid resistance also presents with hypercortisolemia and hypertension but the relationship between salt intake and blood pressure (BP) is not well defined. GRβgeo/+ mice have global glucocorticoid receptor (GR) haploinsufficiency and increased BP. Here we examined the effect of high salt diet on BP, salt excretion and renal blood flow in GRβgeo/+mice. Basal BP was ∼10 mmHg higher in male GRβgeo/+ mice than in GR+/+ littermates. This modest increase was amplified by ∼10 mmHg following a high-salt diet in GRβgeo/+ mice. High salt reduced urinary aldosterone excretion but increased renal mineralocorticoid receptor expression in both genotypes. Corticosterone, and to a lesser extent deoxycorticosterone, excretion was increased in GRβgeo/+ mice following a high-salt challenge, consistent with enhanced 24 h production. GR+/+ mice increased fractional sodium excretion and reduced renal vascular resistance during the high salt challenge, retaining neutral sodium balance. In contrast, sodium excretion and renal vascular resistance did not adapt to high salt in GRβgeo/+ mice, resulting in transient sodium retention and sustained hypertension. With high-salt diet, Slc12a3 and Scnn1a mRNAs were higher in GRβgeo/+ than controls, and this was reflected in an exaggerated natriuretic response to thiazide and benzamil, inhibitors of NCC and ENaC, respectively. Reduction in GR expression causes salt-sensitivity and an adaptive failure of the renal vasculature and tubule, most likely reflecting sustained mineralocorticoid receptor activation. This provides a mechanistic basis to understand the hypertension associated with loss-of-function polymorphisms in GR in the context of habitually high salt intake.
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Affiliation(s)
- Jessica R Ivy
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Louise C Evans
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Rebecca Moorhouse
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Rachel V Richardson
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Emad A S Al-Dujaili
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Peter W Flatman
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Christopher J Kenyon
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Karen E Chapman
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Matthew A Bailey
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
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14
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Mullins LJ, Conway BR, Menzies RI, Denby L, Mullins JJ. Renal disease pathophysiology and treatment: contributions from the rat. Dis Model Mech 2017; 9:1419-1433. [PMID: 27935823 PMCID: PMC5200898 DOI: 10.1242/dmm.027276] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The rat has classically been the species of choice for pharmacological studies and disease modeling, providing a source of high-quality physiological data on cardiovascular and renal pathophysiology over many decades. Recent developments in genome engineering now allow us to capitalize on the wealth of knowledge acquired over the last century. Here, we review rat models of hypertension, diabetic nephropathy, and acute and chronic kidney disease. These models have made important contributions to our understanding of renal diseases and have revealed key genes, such as Ace and P2rx7, involved in renal pathogenic processes. By targeting these genes of interest, researchers are gaining a better understanding of the etiology of renal pathologies, with the promised potential of slowing disease progression or even reversing the damage caused. Some, but not all, of these target genes have proved to be of clinical relevance. However, it is now possible to generate more sophisticated and appropriate disease models in the rat, which can recapitulate key aspects of human renal pathology. These advances will ultimately be used to identify new treatments and therapeutic targets of much greater clinical relevance. Summary: This Review highlights the key role that the rat continues to play in improving our understanding of the etiologies of renal pathologies, and how these insights have opened up new therapeutic avenues.
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Affiliation(s)
- Linda J Mullins
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK
| | - Bryan R Conway
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK
| | - Robert I Menzies
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK
| | - Laura Denby
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK
| | - John J Mullins
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK
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15
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Frindt G, Yang L, Uchida S, Weinstein AM, Palmer LG. Responses of distal nephron Na + transporters to acute volume depletion and hyperkalemia. Am J Physiol Renal Physiol 2017; 313:F62-F73. [PMID: 28356292 DOI: 10.1152/ajprenal.00668.2016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 03/21/2017] [Accepted: 03/21/2017] [Indexed: 01/01/2023] Open
Abstract
We assessed effects of acute volume reductions induced by administration of diuretics in rats. Direct block of Na+ transport produced changes in urinary electrolyte excretion. Adaptations to these effects appeared as alterations in the expression of protein for the distal nephron Na+ transporters NCC and ENaC. Two hours after a single injection of furosemide (6 mg/kg) or hydrochlorothiazide (HCTZ; 30 mg/kg) Na+ and K+ excretion increased but no changes in the content of activated forms of NCC (phosphorylated on residue T53) or ENaC (cleaved γ-subunit) were detected. In contrast, amiloride (0.6 mg/kg) evoked a similar natriuresis that coincided with decreased pT53NCC and increased cleaved γENaC. Alterations in posttranslational membrane protein processing correlated with an increase in plasma K+ of 0.6-0.8 mM. Decreased pT53NCC occurred within 1 h after amiloride injection, whereas changes in γENaC were slower and were blocked by the mineralocorticoid receptor antagonist spironolactone. Increased γENaC cleavage correlated with elevation of the surface expression of the subunit as assessed by in situ biotinylation. Na depletion induced by 2 h of furosemide or HCTZ treatment increases total NCC expression without affecting ENaC protein. However, restriction of Na intake for 10 h (during the day) or 18 h (overnight) increased the abundance of both total NCC and of cleaved α- and γENaC. We conclude that the kidneys respond acutely to hyperkalemic challenges by decreasing the activity of NCC while increasing that of ENaC. They respond to hypovolemia more slowly, increasing Na+ reabsorptive capacities of both of these transporters.
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Affiliation(s)
- Gustavo Frindt
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, New York
| | - Lei Yang
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, New York.,Department of Physiology, Harbin University School of Medicine, Harbin, China; and
| | - Shinichi Uchida
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Alan M Weinstein
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, New York.,Department of Medicine, Weill Cornell Medical College, New York, New York
| | - Lawrence G Palmer
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, New York;
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16
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Walsh KR, Kuwabara JT, Shim JW, Wainford RD. Norepinephrine-evoked salt-sensitive hypertension requires impaired renal sodium chloride cotransporter activity in Sprague-Dawley rats. Am J Physiol Regul Integr Comp Physiol 2015; 310:R115-24. [PMID: 26608659 DOI: 10.1152/ajpregu.00514.2014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 11/11/2015] [Indexed: 01/11/2023]
Abstract
Recent studies have implicated a role of norepinephrine (NE) in the activation of the sodium chloride cotransporter (NCC) to drive the development of salt-sensitive hypertension. However, the interaction between NE and increased salt intake on blood pressure remains to be fully elucidated. This study examined the impact of a continuous NE infusion on sodium homeostasis and blood pressure in conscious Sprague-Dawley rats challenged with a normal (NS; 0.6% NaCl) or high-salt (HS; 8% NaCl) diet for 14 days. Naïve and saline-infused Sprague-Dawley rats remained normotensive when placed on HS and exhibited dietary sodium-evoked suppression of peak natriuresis to hydrochlorothiazide. NE infusion resulted in the development of hypertension, which was exacerbated by HS, demonstrating the development of the salt sensitivity of blood pressure [MAP (mmHg) NE+NS: 151 ± 3 vs. NE+HS: 172 ± 4; P < 0.05]. In these salt-sensitive animals, increased NE prevented dietary sodium-evoked suppression of peak natriuresis to hydrochlorothiazide, suggesting impaired NCC activity contributes to the development of salt sensitivity [peak natriuresis to hydrochlorothiazide (μeq/min) Naïve+NS: 9.4 ± 0.2 vs. Naïve+HS: 7 ± 0.1; P < 0.05; NE+NS: 11.1 ± 1.1; NE+HS: 10.8 ± 0.4). NE infusion did not alter NCC expression in animals maintained on NS; however, dietary sodium-evoked suppression of NCC expression was prevented in animals challenged with NE. Chronic NCC antagonism abolished the salt-sensitive component of NE-mediated hypertension, while chronic ANG II type 1 receptor antagonism significantly attenuated NE-evoked hypertension without restoring NCC function. These data demonstrate that increased levels of NE prevent dietary sodium-evoked suppression of the NCC, via an ANG II-independent mechanism, to stimulate the development of salt-sensitive hypertension.
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Affiliation(s)
- Kathryn R Walsh
- Department of Pharmacology and Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
| | - Jill T Kuwabara
- Department of Pharmacology and Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
| | - Joon W Shim
- Department of Pharmacology and Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
| | - Richard D Wainford
- Department of Pharmacology and Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts
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17
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Menzies RI, Howarth AR, Unwin RJ, Tam FWK, Mullins JJ, Bailey MA. Inhibition of the purinergic P2X7 receptor improves renal perfusion in angiotensin-II-infused rats. Kidney Int 2015; 88:1079-87. [PMID: 26108066 DOI: 10.1038/ki.2015.182] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 04/19/2015] [Accepted: 04/23/2015] [Indexed: 12/14/2022]
Abstract
Chronic activation of the renin-angiotensin system promotes hypertension, renal microvascular dysfunction, tissue hypoxia, and inflammation. Despite similar hypertension, an injurious response to excess angiotensin II is greater in F344 than in Lewis rats; the latter displaying renoprotection. Here we studied whether p2rx7, encoding the P2X7 receptor (P2X7R), is a candidate gene for the differential susceptibility to vascular dysfunction under high angiotensin II tone. A 14-day infusion of angiotensin II into F344 rats increased blood pressure by about 15 mm Hg without inducing fibrosis or albuminuria. In vivo pressure natriuresis was suppressed, medullary perfusion reduced by half, and the corticomedullary oxygenation gradient disrupted. Selective P2X7R antagonism restored pressure natriuresis, promoting a significant leftward shift in the intercept and increasing the slope. Sodium excretion was increased sixfold and blood pressure normalized. The specific P2X7R antagonist AZ11657312 increased renal medullary perfusion, but only in angiotensin II-treated rats. Tissue oxygenation was improved by P2X7R blockade, particularly in poorly oxygenated regions of the kidney. Thus, activation of P2X7R induces microvascular dysfunction and regional hypoxia when angiotensin II is elevated and these effects may contribute to progression of renal injury induced by chronic angiotensin II.
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Affiliation(s)
- Robert I Menzies
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK.,Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, UK
| | - Amelia R Howarth
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK
| | - Robert J Unwin
- Cardiovascular and Metabolic Diseases (iMed CVMD) R&D, AstraZeneca, Mölndal, Sweden.,UCL Centre for Nephrology, University College London, London, UK
| | - Frederick W K Tam
- Imperial College Renal and Transplant Centre, Department of Medicine, Imperial College London, London, UK
| | - John J Mullins
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK
| | - Matthew A Bailey
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK
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18
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Ivy JR, Bailey MA. Pressure natriuresis and the renal control of arterial blood pressure. J Physiol 2014; 592:3955-67. [PMID: 25107929 DOI: 10.1113/jphysiol.2014.271676] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The regulation of extracellular fluid volume by renal sodium excretion lies at the centre of blood pressure homeostasis. Renal perfusion pressure can directly regulate sodium reabsorption in the proximal tubule. This acute pressure natriuresis response is a uniquely powerful means of stabilizing long-term blood pressure around a set point. By logical extension, deviation from the set point can only be sustained if the pressure natriuresis mechanism is impaired, suggesting that hypertension is caused or sustained by a defect in the relationship between renal perfusion pressure and sodium excretion. Here we describe the role of pressure natriuresis in blood pressure control and outline the cascade of biophysical and paracrine events in the renal medulla that integrate the vascular and tubular response to altered perfusion pressure. Pressure natriuresis is impaired in hypertension and mechanistic insight into dysfunction comes from genetic analysis of blood pressure disorders. Transplantation studies in rats show that blood pressure is determined by the genotype of the kidney and Mendelian hypertension indicates that the distal nephron influences the overall natriuretic efficiency. These approaches and the outcomes of genome-wide-association studies broaden our view of blood pressure control, suggesting that renal sympathetic nerve activity and local inflammation can impair pressure natriuresis to cause hypertension. Understanding how these systems interact is necessary to tackle the global burden of hypertension.
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Affiliation(s)
- Jessica R Ivy
- British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
| | - Matthew A Bailey
- British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
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19
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Hošková L, Málek I, Kautzner J, Honsová E, van Dokkum RPE, Husková Z, Vojtíšková A, Varcabová Š, Červenka L, Kopkan L. Tacrolimus-induced hypertension and nephrotoxicity in Fawn-Hooded rats are attenuated by dual inhibition of renin–angiotensin system. Hypertens Res 2014; 37:724-32. [DOI: 10.1038/hr.2014.79] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 02/03/2014] [Accepted: 03/01/2014] [Indexed: 01/13/2023]
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20
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Hunter RW, Ivy JR, Bailey MA. Glucocorticoids and renal Na+ transport: implications for hypertension and salt sensitivity. J Physiol 2014; 592:1731-44. [PMID: 24535442 PMCID: PMC4001748 DOI: 10.1113/jphysiol.2013.267609] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The clinical manifestations of glucocorticoid excess include central obesity, hyperglycaemia, dyslipidaemia, electrolyte abnormalities and hypertension. A century on from Cushing's original case study, these cardinal features are prevalent in industrialized nations. Hypertension is the major modifiable risk factor for cardiovascular and renal disease and reflects underlying abnormalities of Na+ homeostasis. Aldosterone is a master regulator of renal Na+ transport but here we argue that glucocorticoids are also influential, particularly during moderate excess. The hypothalamic–pituitary–adrenal axis can affect renal Na+ homeostasis on multiple levels, systemically by increasing mineralocorticoid synthesis and locally by actions on both the mineralocorticoid and glucocorticoid receptors, both of which are expressed in the kidney. The kidney also expresses both of the 11β-hydroxysteroid dehydrogenase (11βHSD) enzymes. The intrarenal generation of active glucocorticoid by 11βHSD1 stimulates Na+ reabsorption; failure to downregulate the enzyme during adaption to high dietary salt causes salt-sensitive hypertension. The deactivation of glucocorticoid by 11βHSD2 underpins the regulatory dominance for Na+ transport of mineralocorticoids and defines the ‘aldosterone-sensitive distal nephron’. In summary, glucocorticoids can stimulate renal transport processes conventionally attributed to the renin–angiotensin–aldosterone system. Importantly, Na+ and volume homeostasis do not exert negative feedback on the hypothalamic–pituitary–adrenal axis. These actions are therefore clinically relevant and may contribute to the pathogenesis of hypertension in conditions associated with elevated glucocorticoid levels, such as the metabolic syndrome and chronic stress.
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Affiliation(s)
- Robert W Hunter
- University/BHF Centre for Cardiovascular Science, The Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.
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21
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Menzies RI, Unwin RJ, Dash RK, Beard DA, Cowley AW, Carlson BE, Mullins JJ, Bailey MA. Effect of P2X4 and P2X7 receptor antagonism on the pressure diuresis relationship in rats. Front Physiol 2013; 4:305. [PMID: 24187541 PMCID: PMC3807716 DOI: 10.3389/fphys.2013.00305] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 10/03/2013] [Indexed: 12/31/2022] Open
Abstract
Reduced glomerular filtration, hypertension and renal microvascular injury are hallmarks of chronic kidney disease, which has a global prevalence of ~10%. We have shown previously that the Fischer (F344) rat has lower GFR than the Lewis rat, and is more susceptible to renal injury induced by hypertension. In the early stages this injury is limited to the pre-glomerular vasculature. We hypothesized that poor renal hemodynamic function and vulnerability to vascular injury are causally linked and genetically determined. In the present study, normotensive F344 rats had a blunted pressure diuresis relationship, compared with Lewis rats. A kidney microarray was then interrogated using the Endeavour enrichment tool to rank candidate genes for impaired blood pressure control. Two novel candidate genes, P2rx7 and P2rx4, were identified, having a 7− and 3− fold increased expression in F344 rats. Immunohistochemistry localized P2X4 and P2X7 receptor expression to the endothelium of the pre-glomerular vasculature. Expression of both receptors was also found in the renal tubule; however there was no difference in expression profile between strains. Brilliant Blue G (BBG), a relatively selective P2X7 antagonist suitable for use in vivo, was administered to both rat strains. In Lewis rats, BBG had no effect on blood pressure, but increased renal vascular resistance, consistent with inhibition of some basal vasodilatory tone. In F344 rats BBG caused a significant reduction in blood pressure and a decrease in renal vascular resistance, suggesting that P2X7 receptor activation may enhance vasoconstrictor tone in this rat strain. BBG also reduced the pressure diuresis threshold in F344 rats, but did not alter its slope. These preliminary findings suggest a physiological and potential pathophysiological role for P2X7 in controlling renal and/or systemic vascular function, which could in turn affect susceptibility to hypertension-related kidney damage.
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Affiliation(s)
- Robert I Menzies
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh Edinburgh, UK
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22
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Mamenko M, Zaika O, Prieto MC, Jensen VB, Doris PA, Navar LG, Pochynyuk O. Chronic angiotensin II infusion drives extensive aldosterone-independent epithelial Na+ channel activation. Hypertension 2013; 62:1111-1122. [PMID: 24060890 DOI: 10.1161/hypertensionaha.113.01797] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The inability of mineralocorticoid receptor (MR) blockade to reduce hypertension associated with high angiotensin (Ang) II suggests direct actions of Ang II to regulate tubular sodium reabsorption via the epithelial Na(+) channel (ENaC) in the aldosterone-sensitive distal nephron. We used freshly isolated aldosterone-sensitive distal nephron from mice to delineate the synergism and primacy between aldosterone and Ang II in controlling functional ENaC activity. Inhibition of MR specifically prevented the increased number of functionally active ENaC, but not ENaC open probability elicited by a low sodium diet. In contrast, we found no functional role of glucocorticoid receptors in the regulation of ENaC activity by dietary salt intake. Simultaneous inhibition of MR and Ang II type 1 receptors ameliorated the enhanced ENaC activity caused by low dietary salt intake and produced significantly greater natriuresis than either inhibitor alone. Chronic systemic Ang II infusion induced more than 2 times greater increase in ENaC activity than observed during dietary sodium restriction. Importantly, ENaC activity remained greatly above control levels during maximal MR inhibition. We conclude that during variations in dietary salt intake both aldosterone and Ang II contribute complementarily to the regulation of ENaC activity in the aldosterone-sensitive distal nephron. In contrast, in the setting of Ang II-dependent hypertension, ENaC activity is upregulated well above the physiological range and is not effectively suppressed by inhibition of the aldosterone-MR axis. This provides a mechanistic explanation for the resistance to MR inhibition that occurs in hypertensive subjects having elevated intrarenal Ang II levels.
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Affiliation(s)
- Mykola Mamenko
- Department of Integrative Biology and Pharmacology; The University of Texas Health Science Center at Houston, USA
| | - Oleg Zaika
- Department of Integrative Biology and Pharmacology; The University of Texas Health Science Center at Houston, USA
| | - Minolfa C Prieto
- Department of Physiology and Hypertension and Renal Center of Excellence, Tulane University School of Medicine, New Orleans, LA, USA
| | - V Behrana Jensen
- Center for Laboratory Animal Medicine and Care The University of Texas Health Science Center at Houston, USA
| | - Peter A Doris
- Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, USA
| | - L Gabriel Navar
- Department of Physiology and Hypertension and Renal Center of Excellence, Tulane University School of Medicine, New Orleans, LA, USA
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology; The University of Texas Health Science Center at Houston, USA
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23
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Menzies RI, Zammit-Mangion A, Hollis LM, Lennen RJ, Jansen MA, Webb DJ, Mullins JJ, Dear JW, Sanguinetti G, Bailey MA. An anatomically unbiased approach for analysis of renal BOLD magnetic resonance images. Am J Physiol Renal Physiol 2013; 305:F845-52. [DOI: 10.1152/ajprenal.00113.2013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Oxygenation defects may contribute to renal disease progression, but the chronology of events is difficult to define in vivo without recourse to invasive methodologies. Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI) provides an attractive alternative, but the R2* signal is physiologically complex. Postacquisition data analysis often relies on manual selection of region(s) of interest. This approach excludes from analysis significant quantities of biological information and is subject to selection bias. We present a semiautomated, anatomically unbiased approach to compartmentalize voxels into two quantitatively related clusters. In control F344 rats, low R2* clustering was located predominantly within the cortex and higher R2* clustering within the medulla (70.96 ± 1.48 vs. 79.00 ± 1.50; 3 scans per rat; n = 6; P < 0.01) consistent anatomically with a cortico-medullary oxygen gradient. An intravenous bolus of acetylcholine caused a transient reduction of the R2* signal in both clustered segments ( P < 0.01). This was nitric oxide dependent and temporally distinct from the hemodynamic effects of acetylcholine. Rats were then chronically infused with angiotensin II (60 ng/min) and rescanned 3 days later. Clustering demonstrated a disruption of the cortico-medullary gradient, producing less distinctly segmented mean R2* clusters (71.30 ± 2.00 vs. 72.48 ± 1.27; n = 6; NS). The acetylcholine-induced attenuation of the R2* signal was abolished by chronic angiotensin II infusion, consistent with reduced nitric oxide bioavailability. This global map of oxygenation, defined by clustering individual voxels on the basis of quantitative nearness, might be more robust in defining deficits in renal oxygenation than the absolute magnitude of R2* in small, manually selected regions of interest defined exclusively by anatomical nearness.
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Affiliation(s)
- Robert I. Menzies
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom; and
| | | | - Lyam M. Hollis
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom; and
| | - Ross J. Lennen
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom; and
| | - Maurits A. Jansen
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom; and
| | - David J. Webb
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom; and
| | - John J. Mullins
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom; and
| | - James W. Dear
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom; and
| | - Guido Sanguinetti
- School of Informatics, The University of Edinburgh, Edinburgh, United Kingdom
| | - Matthew A. Bailey
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom; and
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Effects of angiotensin II on kinase-mediated sodium and potassium transport in the distal nephron. Curr Opin Nephrol Hypertens 2013; 22:120-6. [PMID: 23165113 DOI: 10.1097/mnh.0b013e32835b6551] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
PURPOSE OF REVIEW The aim is to review the recently reported effects of angiotensin II (Ang II) on sodium and potassium transport in the aldosterone-sensitive distal nephron, including the signaling pathways between receptor and transporter, and the (patho)physiological implications of these findings. RECENT FINDINGS Ang II can activate the sodium chloride cotransporter (NCC) through phosphorylation by Ste20-related, proline-alanine rich kinase (SPAK), an effect that is independent of aldosterone but dependent on with no lysine kinase 4 (WNK4). A low-sodium diet (high Ang II) activates NCC, whereas a high-potassium diet (low Ang II) inhibits NCC. NCC activation also contributes to Ang-II-mediated hypertension. Ang II also activates the epithelial sodium channel (ENaC) additively to aldosterone, and this effect appears to be mediated through protein kinase C and superoxide generation by nicotinamide adenine dinucleotide phosphate oxidase. While aldosterone activates the renal outer medullary potassium channel (ROMK), this channel is inhibited by Ang II. The key kinase responsible for this effect is c-Src, which phosphorylates ROMK and leaves WNK4 unphosphorylated to further inhibit ROMK. SUMMARY The effects of Ang II on NCC, ENaC, and ROMK help explain the renal response to hypovolemia which is to conserve both sodium and potassium. Pathophysiologically, Ang-II-induced activation of NCC appears to contribute to salt-sensitive hypertension.
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Prieto MC, Gonzalez AA, Navar LG. Evolving concepts on regulation and function of renin in distal nephron. Pflugers Arch 2012; 465:121-32. [PMID: 22990760 DOI: 10.1007/s00424-012-1151-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 08/24/2012] [Accepted: 08/30/2012] [Indexed: 01/13/2023]
Abstract
Sustained stimulation of the intrarenal/intratubular renin-angiotensin system in a setting of elevated arterial pressure elicits renal vasoconstriction, increased sodium reabsorption, proliferation, fibrosis, and eventual renal injury. Activation of luminal AT(1) receptors in proximal and distal nephron segments by local Ang II formation stimulates various transport systems. Augmented angiotensinogen (AGT) production by proximal tubule cells increases AGT secretion contributing to increased proximal Ang II levels and leading to spillover of AGT into the distal nephron segments, as reflected by increased urinary AGT excretion. The increased distal delivery of AGT provides substrate for renin, which is expressed in principal cells of the collecting tubule and collecting ducts, and is also stimulated by AT(1) receptor activation. Renin and prorenin are secreted into the tubular lumen and act on the AGT delivered from the proximal tubule to form more Ang I. The catalytic actions of renin and or prorenin may be enhanced by binding to prorenin receptors on the intercalated cells or soluble prorenin receptor secreted into the tubular fluid. There is also increased luminal angiotensin converting enzyme in collecting ducts facilitating Ang II formation leading to stimulation of sodium reabsorption via sodium channel and sodium/chloride co-transporter. Thus, increased collecting duct renin contributes to Ang II-dependent hypertension by augmenting distal nephron intratubular Ang II formation leading to sustained stimulation of sodium reabsorption and progression of hypertension.
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Affiliation(s)
- Minolfa C Prieto
- Department of Physiology and Hypertension and Renal Center of Excellence, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA
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