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Ito H, Hirose T, Sato S, Takahashi C, Ishikawa R, Endo A, Kamada A, Oba-Yabana I, Kimura T, Murakami K, Nakamura Y, Takahashi K, Mori T. Pericyte detachment and renal congestion involve interstitial injury and fibrosis in Dahl salt-sensitive rats and humans with heart failure. Hypertens Res 2023; 46:2705-2717. [PMID: 37845397 PMCID: PMC10695822 DOI: 10.1038/s41440-023-01451-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 08/13/2023] [Accepted: 09/07/2023] [Indexed: 10/18/2023]
Abstract
Congestive heart failure produces fluid volume overload, central and renal venous pressure elevation, and consequently renal congestion, which results in worsening renal function. Pericyte detachment and pericyte-myofibroblast transition (PMT) were linked to renal interstitial fibrosis. Dahl salt-sensitive hypertensive (DahlS) rats are a non-surgical renal congestion model. The relation, however, between renal interstitial damage, pericyte morphology, and PMT in the renal congestion of DahlS rats has not been reported. DahlS rats (8-week-old) were fed normal salt (NS, 0.4% NaCl) or high salt (HS, 4% NaCl), and the left kidney was decapsulated to reduce renal interstitial hydrostatic pressure (RIHP) at 9 weeks old. One week after capsulotomy, both kidneys were analyzed by molecular and histological techniques. Renal pericyte structure was assessed in the body donors with/without venous stasis. Markers of tubulointerstitial damage, interstitial fibrosis, and PMT were upregulated in the right non-decapsulated kidney of DahlS rats fed HS. Renal tubular injury and fibrosis were detected in the HS diet groups in histological analysis. Pericyte detachment was observed in the right non-decapsulated kidney of DahlS rats fed HS by low vacuum-scanning electron microscopy. Decapsulation in DahlS rats fed HS attenuated these findings. Also, renal pericytes detached from the vascular wall in patients with heart failure. These results suggest that pericyte detachment and PMT induced by increased RIHP are responsible for tubulointerstitial injury and fibrosis in DahlS rats and humans with renal congestion. Renal venous congestion and subsequent physiological changes could be therapeutic targets for renal damage in cardiorenal syndrome.
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Affiliation(s)
- Hiroki Ito
- Division of Nephrology and Endocrinology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
- Department of Endocrinology and Applied Medical Science, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Takuo Hirose
- Division of Nephrology and Endocrinology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan.
- Department of Endocrinology and Applied Medical Science, Tohoku University Graduate School of Medicine, Sendai, Japan.
- Division of Integrative Renal Replacement Therapy, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan.
| | - Shigemitsu Sato
- Division of Integrative Renal Replacement Therapy, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Chika Takahashi
- Division of Integrative Renal Replacement Therapy, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Risa Ishikawa
- Division of Nephrology and Endocrinology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Akari Endo
- Division of Nephrology and Endocrinology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
- Department of Endocrinology and Applied Medical Science, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Ayaka Kamada
- Division of Nephrology and Endocrinology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Ikuko Oba-Yabana
- Division of Nephrology and Endocrinology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Tomoyoshi Kimura
- Division of Nephrology and Endocrinology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Kazuhiro Murakami
- Division of Pathology, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Yasuhiro Nakamura
- Division of Pathology, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Kazuhiro Takahashi
- Department of Endocrinology and Applied Medical Science, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Takefumi Mori
- Division of Nephrology and Endocrinology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan.
- Division of Integrative Renal Replacement Therapy, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan.
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Abe M, Hemmi S, Kobayashi H. How should we treat acute kidney injury caused by renal congestion? Kidney Res Clin Pract 2023; 42:415-430. [PMID: 37098670 PMCID: PMC10407633 DOI: 10.23876/j.krcp.22.224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/28/2022] [Accepted: 10/29/2022] [Indexed: 04/27/2023] Open
Abstract
Decreased kidney function is associated with increased risk of cardiovascular events and mortality, and heart failure (HF) is a wellknown risk factor for renal dysfunction. Acute kidney injury (AKI) in patients with HF often is attributed to prerenal factors, such as renal hypoperfusion and ischemia as a result of decreased cardiac output. Another such factor is reduction of absolute or relative circulating blood volume, with the decrease in renal blood flow leading to renal hypoxia followed by a decrease in the glomerular filtration rate. However, renal congestion is increasingly being recognized as a potential cause of AKI in patients with HF. Increased central venous pressure and renal venous pressure lead to increased renal interstitial hydrostatic pressure and a reduction of the glomerular filtration rate. Both decreased kidney function and renal congestion have been shown to be important prognostic factors of HF, and adequate control of congestion is important for improving kidney function. Loop and thiazide diuretics are recommended as standard therapies to reduce volume overload. However, these agents are associated with worsening renal function even though they are effective for improving congestive symptoms. There is growing interest in tolvaptan, which can improve renal congestion by increasing excretion of free water and decreasing the required dose of loop diuretic, thereby improving kidney function. This review summarizes renal hemodynamics, the pathogenesis of AKI due to renal ischemia and renal congestion, and diagnosis and treatment options for renal congestion.
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Affiliation(s)
- Masanori Abe
- Division of Nephrology, Hypertension and Endocrinology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan
| | - Seiichiro Hemmi
- Division of Nephrology, Hypertension and Endocrinology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan
| | - Hiroki Kobayashi
- Division of Nephrology, Hypertension and Endocrinology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan
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Renal sympathetic activity: A key modulator of pressure natriuresis in hypertension. Biochem Pharmacol 2023; 208:115386. [PMID: 36535529 DOI: 10.1016/j.bcp.2022.115386] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 12/11/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022]
Abstract
Hypertension is a complex disorder ensuing necessarily from alterations in the pressure-natriuresis relationship, the main determinant of long-term control of blood pressure. This mechanism sets natriuresis to the level of blood pressure, so that increasing pressure translates into higher osmotically driven diuresis to reduce volemia and control blood pressure. External factors affecting the renal handling of sodium regulate the pressure-natriuresis relationship so that more or less natriuresis is attained for each level of blood pressure. Hypertension can thus only develop following primary alterations in the pressure to natriuresis balance, or by abnormal activity of the regulation network. On the other hand, increased sympathetic tone is a very frequent finding in most forms of hypertension, long regarded as a key element in the pathophysiological scenario. In this article, we critically analyze the interplay of the renal component of the sympathetic nervous system and the pressure-natriuresis mechanism in the development of hypertension. A special focus is placed on discussing recent findings supporting a role of baroreceptors as a component, along with the afference of reno-renal reflex, of the input to the nucleus tractus solitarius, the central structure governing the long-term regulation of renal sympathetic efferent tone.
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Inhibition of platelet-derived growth factor pathway suppresses tubulointerstitial injury in renal congestion. J Hypertens 2022; 40:1935-1949. [PMID: 35983805 PMCID: PMC9451920 DOI: 10.1097/hjh.0000000000003191] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Increased central venous pressure in congestive heart failure is responsible for renal dysfunction, which is mediated by renal venous congestion. Pericyte detachment from capillaries after renal congestion might trigger renal fibrogenesis via pericyte-myofibroblast transition (PMT). Platelet-derived growth factor receptors (PDGFRs), which are PMT indicators, were upregulated in our recently established renal congestion model. This study was designed to determine whether inhibition of the PDGFR pathway could suppress tubulointerstitial injury after renal congestion. METHODS The inferior vena cava between the renal veins was ligated in male Sprague-Dawley rats, inducing congestion only in the left kidney. Imatinib mesylate or vehicle were injected intraperitoneally daily from 1 day before the operation. Three days after the surgery, the effect of imatinib was assessed by physiological, morphological and molecular methods. The inhibition of PDGFRs against transforming growth factor-β1 (TGFB1)-induced fibrosis was also tested in human pericyte cell culture. RESULTS Increased kidney weight and renal fibrosis were observed in the congested kidneys. Upstream inferior vena cava (IVC) pressure immediately increased to around 20 mmHg after IVC ligation in both the imatinib and saline groups. Although vasa recta dilatation and pericyte detachment under renal congestion were maintained, imatinib ameliorated the increased kidney weight and suppressed renal fibrosis around the vasa recta. TGFB1-induced elevation of fibrosis markers in human pericytes was suppressed by PDGFR inhibitors at the transcriptional level. CONCLUSION The activation of the PDGFR pathway after renal congestion was responsible for renal congestion-induced fibrosis. This mechanism could be a candidate therapeutic target for renoprotection against renal congestion-induced tubulointerstitial injury.
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Shimada S, Yang C, Kumar V, Mattson DL, Cowley AW. Acute Increase of Renal Perfusion Pressure Causes Rapid Activation of mTORC1 (Mechanistic Target Of Rapamycin Complex 1) and Leukocyte Infiltration. Hypertension 2022; 79:1180-1189. [PMID: 35291809 PMCID: PMC9098670 DOI: 10.1161/hypertensionaha.121.18643] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 02/25/2022] [Indexed: 11/16/2022]
Abstract
BACKGROUND The present study in Sprague-Dawley rats determined the effects of a rapid rise of renal perfusion pressure (RPP) upon the activation of mTOR (mechanistic target of rapamycin), and the effects upon the infiltration of CD68-positive macrophages/monocytes and CD3-positive T lymphocytes into the kidneys. METHODS RPP was elevated by 40 mm Hg for 30 minutes in male Sprague-Dawley rats while measuring renal blood flow and urine flow rate. Sham rats were studied in the same way, but RPP was not changed. Since initial studies found that the acute increase of RPP resulted in activation of mTORC1 (phosphorylation of S6S235/236), the effects of inhibition of mTORC1 with rapamycin pretreatment were then determined. RESULTS It was found that a 30-minute increase of RPP (≈40 mm Hg) resulted in an 8-fold increase of renal sodium excretion which was blunted by rapamycin treatment. Renal blood flow was not affected by the elevation of RPP. Activation of mTORC1 was observed. Significant increases in CD68-positive macrophages were found in both the cortex (intraglomerular and periglomerular regions) and in the outer medullary interstitial regions of the kidney and prevented by rapamycin treatment. Increases in CD3-positive T lymphocytes were observed exclusively in the periglomerular regions and prevented by rapamycin treatment. Upregulation of several proinflammatory markers was observed. CONCLUSIONS We conclude that elevation of RPP rapidly activates mTORC1 resulting in infiltration of immune cells into the kidney.
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Affiliation(s)
- Satoshi Shimada
- Department of Physiology, Medical College of Wisconsin, Milwaukee (S.S., C.Y., V.K., D.L.M., A.W.C.)
| | - Chun Yang
- Department of Physiology, Medical College of Wisconsin, Milwaukee (S.S., C.Y., V.K., D.L.M., A.W.C.)
| | - Vikash Kumar
- Department of Physiology, Medical College of Wisconsin, Milwaukee (S.S., C.Y., V.K., D.L.M., A.W.C.)
| | - David L Mattson
- Department of Physiology, Medical College of Wisconsin, Milwaukee (S.S., C.Y., V.K., D.L.M., A.W.C.)
- Now with: Department of Physiology, Medical College of Georgia at Augusta University (D.L.M.)
| | - Allen W Cowley
- Department of Physiology, Medical College of Wisconsin, Milwaukee (S.S., C.Y., V.K., D.L.M., A.W.C.)
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Abstract
Heart failure with preserved ejection fraction (HFpEF) and chronic kidney disease (CKD) constitute a high-risk phenotype with significant morbidity and mortality and poor prognosis. Multiple proinflammatory comorbid conditions influence the pathogenesis of HFpEF and CKD. Renal dysfunction in HFpEF is a consequence of the complex interplay between hemodynamic factors, systemic congestion, inflammation, endothelial dysfunction, and neurohormonal mechanisms. In contrast to heart failure with reduced ejection fraction, there is a dearth of effective targeted therapies for HFpEF. Tailoring study design toward the different phenotypes and delving into their pathophysiology may be fruitful in development of effective phenotype-specific targeted pharmaceutical therapies.
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Affiliation(s)
- Manjula G Ananthram
- Department of Internal Medicine, Division of Cardiology, University of Maryland, 110 South Paca Street, 7th Floor, Baltimore, MD 21201, USA.
| | - Stephen S Gottlieb
- Department of Internal Medicine, Division of Cardiology, University of Maryland, 110 South Paca Street, 7th Floor, Baltimore, MD 21201, USA
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Pavlov TS, Palygin O, Isaeva E, Levchenko V, Khedr S, Blass G, Ilatovskaya DV, Cowley AW, Staruschenko A. NOX4-dependent regulation of ENaC in hypertension and diabetic kidney disease. FASEB J 2020; 34:13396-13408. [PMID: 32799394 DOI: 10.1096/fj.202000966rr] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 07/17/2020] [Accepted: 07/20/2020] [Indexed: 12/11/2022]
Abstract
NADPH oxidase 4 (NOX4) is the most abundant NOX isoform in the kidney; however, its importance for renal function has only recently emerged. The NOX4-dependent pathway regulates many factors essential for proper sodium handling in the distal nephron. However, the functional significance of this pathway in the control of sodium reabsorption during the initiation of chronic kidney disease is not established. The goal of this study was to test Nox4-dependent ENaC regulation in two models: SS hypertension and STZ-induced type 1 diabetes. First, we showed that genetic ablation of Nox4 in Dahl salt-sensitive (SS) rat attenuated a high-salt (HS)-induced increase in epithelial Na+ channel (ENaC) activity in the cortical collecting duct. We also found that H2 O2 upregulated ENaC activity, and H2 O2 production was reduced in both the renal cortex and medulla in SSNox4-/- rats fed an HS diet. Second, in the streptozotocin model of hyperglycemia-induced renal injury ENaC activity in hyperglycemic animals was elevated in SS but not SSNox4-/- rats. NaCl cotransporter (NCC) expression was increased compared to healthy controls, while expression values between SS and SSNox4-/- groups were similar. These data emphasize a critical contribution of the NOX4-mediated pathway in maladaptive upregulation of ENaC-mediated sodium reabsorption in the distal nephron in the conditions of HS- and hyperglycemia-induced kidney injury.
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Affiliation(s)
- Tengis S Pavlov
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA.,Division of Hypertension and Vascular Research, Henry Ford Health System, Detroit, MI, USA
| | - Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Elena Isaeva
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | | | - Sherif Khedr
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA.,Department of Physiology, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Gregory Blass
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | | | - Allen W Cowley
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Alexander Staruschenko
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA.,Clement J. Zablocki VA Medical Center, Milwaukee, WI, USA
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Shimada S, Abais-Battad JM, Alsheikh AJ, Yang C, Stumpf M, Kurth T, Mattson DL, Cowley AW. Renal Perfusion Pressure Determines Infiltration of Leukocytes in the Kidney of Rats With Angiotensin II-Induced Hypertension. Hypertension 2020; 76:849-858. [PMID: 32755400 DOI: 10.1161/hypertensionaha.120.15295] [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: 01/11/2023]
Abstract
The present study examined the extent to which leukocyte infiltration into the kidneys in Ang II (angiotensin II)-induced hypertension is determined by elevation of renal perfusion pressure (RPP). Male Sprague-Dawley rats were instrumented with carotid and femoral arterial catheters for continuous monitoring of blood pressure and a femoral venous catheter for infusion. An inflatable aortic occluder cuff placed between the renal arteries with computer-driven servo-controller maintained RPP to the left kidney at control levels during 7 days of intravenous Ang II (50 ng/kg per minute) or vehicle (saline) infusion. Rats were fed a 0.4% NaCl diet throughout the study. Ang II-infused rats exhibited nearly a 50 mm Hg increase of RPP (carotid catheter) to the right kidney while RPP to the left kidney (femoral catheter) was controlled at baseline pressure throughout the study. As determined at the end of the studies by flow cytometry, right kidneys exhibited significantly greater numbers of T cells, B cells, and monocytes/macrophages compared with the servo-controlled left kidneys and compared with vehicle treated rats. No difference was found between Ang II servo-controlled left kidneys and vehicle treated kidneys. Immunostaining found that the density of glomeruli, cortical, and outer medullary capillaries were significantly reduced in the right kidney of Ang II-infused rats compared with servo-controlled left kidney. We conclude that in this model of hypertension the elevation of RPP, not Ang II nor dietary salt, leads to leukocyte infiltration in the kidney and to capillary rarefaction.
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Affiliation(s)
- Satoshi Shimada
- From the Department of Physiology, Medical College of Wisconsin, Milwaukee
| | | | - Ammar J Alsheikh
- From the Department of Physiology, Medical College of Wisconsin, Milwaukee
| | - Chun Yang
- From the Department of Physiology, Medical College of Wisconsin, Milwaukee
| | - Megan Stumpf
- From the Department of Physiology, Medical College of Wisconsin, Milwaukee
| | - Theresa Kurth
- From the Department of Physiology, Medical College of Wisconsin, Milwaukee
| | - David L Mattson
- From the Department of Physiology, Medical College of Wisconsin, Milwaukee
| | - Allen W Cowley
- From the Department of Physiology, Medical College of Wisconsin, Milwaukee
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Sowers JR, Habibi J, Aroor AR, Yang Y, Lastra G, Hill MA, Whaley-Connell A, Jaisser F, Jia G. Epithelial sodium channels in endothelial cells mediate diet-induced endothelium stiffness and impaired vascular relaxation in obese female mice. Metabolism 2019; 99:57-66. [PMID: 31302199 PMCID: PMC6901094 DOI: 10.1016/j.metabol.2019.153946] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 07/10/2019] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Mineralocorticoid receptor activation of the epithelial sodium channel in endothelial cells (ECs) (EnNaC) is accompanied by aldosterone induced endothelial stiffening and impaired nitric oxide (NO)-mediated arterial relaxation. Recent data support enhanced activity of the alpha subunit of EnNaC (αEnNaC) mediates this aldosterone induced endothelial stiffening and associated endothelial NO synthase (eNOS) activation. There is mounting evidence that diet induced obesity diminishes expression and activation of AMP-activated protein kinase α (AMPKα), sirtuin 1 (Sirt1), which would be expected to lead to impaired downstream eNOS activation. Thereby, we posited that enhanced EnNaC activation contributes to diet induced obesity related increases in stiffness of the endothelium and diminished NO mediated vascular relaxation by increasing oxidative stress and related inhibition of AMPKα, Sirt1, and associated eNOS inactivation. MATERIALS/METHODS Sixteen to twenty week-old αEnNaC knockout (αEnNaC-/-) and wild type littermate (EnNaC+/+) female mice were fed a mouse chow or an obesogenic western diet (WD) containing excess fat (46%) and fructose (17.5%) for 16 weeks. Sodium currents of ECs, endothelial stiffness and NO mediated aortic relaxation were examined along with indices of aortic oxidative stress, vascular remodeling and fibrosis. RESULTS Enhanced EnNaC activation-mediated WD-induced increases in sodium currents in isolated lung ECs, increased endothelial stiffness and impaired aortic endothelium-dependent relaxation to acetylcholine (10-9-10-4 mol/L). These abnormalities occurred in conjunction with WD-mediated aortic tissue oxidative stress, inflammation, and decreased activation of AMPKα, Sirt1, and downstream eNOS were substantially mitigated in αEnNaC-/- mice. Importantly, αEnNaC-/- prevented WD induced increases in endothelial stiffness and related impairment of endothelium-dependent relaxation as well as aortic fibrosis and remodeling. However, EnNaC signaling was not involved in diet-induced abnormal expression of adipokines and CYP11b2 in abdominal aortic perivascular adipose tissue. CONCLUSION These data suggest that endothelial specific EnNaC activation mediates WD-induced endothelial stiffness, impaired eNOS activation, aortic fibrosis and remodeling through increased aortic oxidative stress and increased inflammation related to a reduction of AMPKα and Sirt 1 mediated eNOS phosphorylation/activation and NO production.
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Affiliation(s)
- James R Sowers
- Diabetes and Cardiovascular Center, University of Missouri School of Medicine, Columbia, MO 65212, USA; Research Service, Harry S Truman Memorial Veterans Hospital, 800 Hospital Dr, Columbia, MO 65201, USA; Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65212, USA; Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO 65212, USA
| | - Javad Habibi
- Diabetes and Cardiovascular Center, University of Missouri School of Medicine, Columbia, MO 65212, USA; Research Service, Harry S Truman Memorial Veterans Hospital, 800 Hospital Dr, Columbia, MO 65201, USA
| | - Annayya R Aroor
- Diabetes and Cardiovascular Center, University of Missouri School of Medicine, Columbia, MO 65212, USA; Research Service, Harry S Truman Memorial Veterans Hospital, 800 Hospital Dr, Columbia, MO 65201, USA
| | - Yan Yang
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65212, USA
| | - Guido Lastra
- Diabetes and Cardiovascular Center, University of Missouri School of Medicine, Columbia, MO 65212, USA; Research Service, Harry S Truman Memorial Veterans Hospital, 800 Hospital Dr, Columbia, MO 65201, USA
| | - Michael A Hill
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65212, USA; Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO 65212, USA
| | - Adam Whaley-Connell
- Diabetes and Cardiovascular Center, University of Missouri School of Medicine, Columbia, MO 65212, USA; Research Service, Harry S Truman Memorial Veterans Hospital, 800 Hospital Dr, Columbia, MO 65201, USA; Department of Medicine, University of Missouri School of Medicine, Columbia, MO 65212, USA
| | - Frederic Jaisser
- INSERM, UMRS 1138, Cordeliers Research Center, Sorbonne University, USPC, Université Paris Descartes, Université Paris Diderot, F-75006 Paris, France
| | - Guanghong Jia
- Diabetes and Cardiovascular Center, University of Missouri School of Medicine, Columbia, MO 65212, USA; Research Service, Harry S Truman Memorial Veterans Hospital, 800 Hospital Dr, Columbia, MO 65201, USA; Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65212, USA; Department of Medicine, University of Missouri School of Medicine, Columbia, MO 65212, USA.
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Pathophysiological and molecular mechanisms involved in renal congestion in a novel rat model. Sci Rep 2018; 8:16808. [PMID: 30429498 PMCID: PMC6235885 DOI: 10.1038/s41598-018-35162-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 10/29/2018] [Indexed: 01/18/2023] Open
Abstract
Increased central venous pressure in congestive heart failure causes renal dysfunction; however, the underlying mechanisms are unclear. We created a rat renal congestion model and investigated the effect of renal congestion on hemodynamics and molecular mechanisms. The inferior vena cava (IVC) between the renal veins was ligated by suture in male Sprague-Dawley rats to increase upstream IVC pressure and induce congestion in the left kidney only. Left kidney congestion reduced renal blood flow, glomerular filtration rate, and increased renal interstitial hydrostatic pressure. Tubulointerstitial and glomerular injury and medullary thick ascending limb hypoxia were observed only in the congestive kidneys. Molecules related to extracellular matrix expansion, tubular injury, and focal adhesion were upregulated in microarray analysis. Renal decapsulation ameliorated the tubulointerstitial injury. Electron microscopy captured pericyte detachment in the congestive kidneys. Transgelin and platelet-derived growth factor receptors, as indicators of pericyte-myofibroblast transition, were upregulated in the pericytes and the adjacent interstitium. With the compression of the peritubular capillaries and tubules, hypoxia and physical stress induce pericyte detachment, which could result in extracellular matrix expansion and tubular injury in renal congestion.
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11
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Palygin O, Evans LC, Cowley AW, Staruschenko A. Acute In Vivo Analysis of ATP Release in Rat Kidneys in Response to Changes of Renal Perfusion Pressure. J Am Heart Assoc 2017; 6:JAHA.117.006658. [PMID: 28899893 PMCID: PMC5634305 DOI: 10.1161/jaha.117.006658] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Background ATP and derivatives are recognized to be essential agents of paracrine signaling. It was reported that ATP is an important regulator of the pressure‐natriuresis mechanism. Information on the sources of ATP, the mechanisms of its release, and its relationship to blood pressure has been limited by the inability to precisely measure dynamic changes in intrarenal ATP levels in vivo. Methods and Results Newly developed amperometric biosensors were used to assess alterations in cortical ATP concentrations in response to changes in renal perfusion pressure (RPP) in anesthetized Sprague–Dawley rats. RPP was monitored via the carotid artery; ligations around the celiac/superior mesenteric arteries and the distal aorta were used for manipulation of RPP. Biosensors were acutely implanted in the renal cortex for assessment of ATP. Rise of RPP activated diuresis/natriuresis processes, which were associated with elevated ATP. The increases in cortical ATP concentrations were in the physiological range (1–3 μmol/L) and would be capable of activating most of the purinergic receptors. There was a linear correlation with every 1‐mm Hg rise in RPP resulting in a 70‐nmol/L increase in ATP. Furthermore, this elevation of RPP was accompanied by a 2.5‐fold increase in urinary H2O2. Conclusions Changes in RPP directly correlate with renal sodium excretion and the elevation of cortical ATP. Given the known effects of ATP on regulation of glomerular filtration and tubular transport, the data support a role for ATP release in the rapid natriuretic responses to acute increases in RPP.
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Affiliation(s)
- Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI
| | - Louise C Evans
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI
| | - Allen W Cowley
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI
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12
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Pavlov TS, Staruschenko A. Involvement of ENaC in the development of salt-sensitive hypertension. Am J Physiol Renal Physiol 2016; 313:F135-F140. [PMID: 28003189 DOI: 10.1152/ajprenal.00427.2016] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 12/20/2016] [Accepted: 12/20/2016] [Indexed: 02/07/2023] Open
Abstract
Salt-sensitive hypertension is associated with renal and vascular dysfunctions, which lead to impaired fluid excretion, increased cardiac output, and total peripheral resistance. It is commonly accepted that increased renal sodium handling and plasma volume expansion are necessary factors for the development of salt-induced hypertension. The epithelial sodium channel (ENaC) is a trimeric ion channel expressed in the distal nephron that plays a critical role in the regulation of sodium reabsorption in both normal and pathological conditions. In this mini-review, we summarize recent studies investigating the role of ENaC in the development of salt-sensitive hypertension. On the basis of experimental data obtained from the Dahl salt-sensitive rats, we and others have demonstrated that abnormal ENaC activation in response to a dietary NaCl load contributes to the development of high blood pressure in this model. The role of different humoral factors, such as the components of the renin-angiotensin-aldosterone system, members of the epidermal growth factors family, arginine vasopressin, and oxidative stress mediating the effects of dietary salt on ENaC are discussed in this review to highlight future research directions and to determine potential molecular targets for drug development.
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Affiliation(s)
- Tengis S Pavlov
- Division of Hypertension and Vascular Research, Henry Ford Hospital, Detroit, Michigan; and
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13
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Wang L, Song J, Buggs J, Wei J, Wang S, Zhang J, Zhang G, Lu Y, Yip KP, Liu R. A new mouse model of hemorrhagic shock-induced acute kidney injury. Am J Physiol Renal Physiol 2016; 312:F134-F142. [PMID: 28042109 DOI: 10.1152/ajprenal.00347.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 10/25/2016] [Accepted: 10/31/2016] [Indexed: 11/22/2022] Open
Abstract
Current animal models of hemorrhagic shock-induced acute kidney injury (HS-induced AKI) require extensive surgical procedures and constant monitoring of hemodynamic parameters. Application of these HS-induced AKI models in mice to produce consistent kidney injury is challenging. In the present study, we developed a simple and highly reproducible mouse model of HS-induced AKI by combining moderate bleeding and renal pedicle clamping, which was abbreviated as HS-AKI. HS was induced by retroorbital bleeding of 0.4 ml blood in C57BL/6 mice. Mice were left in HS stage for 30 min, followed by renal pedicle clamping for 18 min at 36.8-37.0°C. Mean arterial pressure (MAP) and heart rate were monitored with preimplanted radio transmitters throughout the experiment. The acute response in renal blood flow (RBF) triggered by HS was measured with transonic flow probe. Mice received sham operation; bleeding alone and renal pedicle clamping alone served as respective controls. MAP was reduced from 77 ± 4 to 35 ± 3 mmHg after bleeding. RBF was reduced by 65% in the HS period. Plasma creatinine and kidney injury molecule-1 levels were increased by more than 22-fold 24 h after reperfusion. GFR was declined by 78% of baseline 3 days after reperfusion. Histological examination revealed a moderate-to-severe acute tubular damage, mostly at the cortex-medulla junction area, followed by the medullar and cortex regions. HS alone did not induce significant kidney injury, but synergistically enhanced pedicle clamping-induced AKI. This is a well-controlled, simple, and reliable mouse model of HS-AKI.
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Affiliation(s)
- Lei Wang
- Department of Molecular Pharmacology & Physiology, University of South Florida College of Medicine, Tampa, Florida;
| | - Jiangping Song
- Department of Molecular Pharmacology & Physiology, University of South Florida College of Medicine, Tampa, Florida
| | | | - Jin Wei
- Department of Molecular Pharmacology & Physiology, University of South Florida College of Medicine, Tampa, Florida
| | - Shaohui Wang
- Department of Molecular Pharmacology & Physiology, University of South Florida College of Medicine, Tampa, Florida
| | - Jie Zhang
- Department of Molecular Pharmacology & Physiology, University of South Florida College of Medicine, Tampa, Florida
| | - Gensheng Zhang
- Department of Molecular Pharmacology & Physiology, University of South Florida College of Medicine, Tampa, Florida.,Department of Physiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Yan Lu
- Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi; and
| | - Kay-Pong Yip
- Department of Molecular Pharmacology & Physiology, University of South Florida College of Medicine, Tampa, Florida
| | - Ruisheng Liu
- Department of Molecular Pharmacology & Physiology, University of South Florida College of Medicine, Tampa, Florida
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Palygin O, Levchenko V, Evans LC, Blass G, Cowley AW, Staruschenko A. Use of Enzymatic Biosensors to Quantify Endogenous ATP or H2O2 in the Kidney. J Vis Exp 2015. [PMID: 26485400 DOI: 10.3791/53059] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Enzymatic microelectrode biosensors have been widely used to measure extracellular signaling in real-time. Most of their use has been limited to brain slices and neuronal cell cultures. Recently, this technology has been applied to the whole organs. Advances in sensor design have made possible the measuring of cell signaling in blood-perfused in vivo kidneys. The present protocols list the steps needed to measure ATP and H2O2 signaling in the rat kidney interstitium. Two separate sensor designs are used for the ex vivo and in vivo protocols. Both types of sensor are coated with a thin enzymatic biolayer on top of a permselectivity layer to give fast responding, sensitive and selective biosensors. The permselectivity layer protects the signal from the interferents in biological tissue, and the enzymatic layer utilizes the sequential catalytic reaction of glycerol kinase and glycerol-3-phosphate oxidase in the presence of ATP to produce H2O2. The set of sensors used for the ex vivo studies further detected analyte by oxidation of H2O2 on a platinum/iridium (Pt-Ir) wire electrode. The sensors for the in vivo studies are instead based on the reduction of H2O2 on a mediator coated gold electrode designed for blood-perfused tissue. Final concentration changes are detected by real-time amperometry followed by calibration to known concentrations of analyte. Additionally, the specificity of the amperometric signal can be confirmed by the addition of enzymes such as catalase and apyrase that break down H2O2 and ATP correspondingly. These sensors also rely heavily on accurate calibrations before and after each experiment. The following two protocols establish the study of real-time detection of ATP and H2O2 in kidney tissues, and can be further modified to extend the described method for use in other biological preparations or whole organs.
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Affiliation(s)
- Oleg Palygin
- Department of Physiology, Medical College of Wisconsin
| | | | | | - Gregory Blass
- Department of Physiology, Medical College of Wisconsin
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15
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Lin CS, Lee SH, Huang HS, Chen YS, Ma MC. H2O2 generated by NADPH oxidase 4 contributes to transient receptor potential vanilloid 1 channel-mediated mechanosensation in the rat kidney. Am J Physiol Renal Physiol 2015; 309:F369-76. [PMID: 26136558 DOI: 10.1152/ajprenal.00462.2014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 06/17/2015] [Indexed: 11/22/2022] Open
Abstract
The presence of NADPH oxidase (Nox) in the kidney, especially Nox4, results in H2O2 production, which regulates Na(+) excretion and urine formation. Redox-sensitive transient receptor potential vanilloid 1 channels (TRPV1s) are distributed in mechanosensory fibers of the renal pelvis and monitor changes in intrapelvic pressure (IPP) during urine formation. The present study tested whether H2O2 derived from Nox4 affects TRPV1 function in renal sensory responses. Perfusion of H2O2 into the renal pelvis dose dependently increased afferent renal nerve activity and substance P (SP) release. These responses were attenuated by cotreatment with catalase or TRPV1 blockers. In single unit recordings, H2O2 activated afferent renal nerve activity in response to rising IPP but not high salt. Western blots revealed that Nox2 (gp91(phox)) and Nox4 are both present in the rat kidney, but Nox4 is abundant in the renal pelvis and originates from dorsal root ganglia. This distribution was associated with expression of the Nox4 regulators p22(phox) and polymerase δ-interacting protein 2. Coimmunoprecipitation experiments showed that IPP increases polymerase δ-interacting protein 2 association with Nox4 or p22(phox) in the renal pelvis. Interestingly, immunofluorescence labeling demonstrated that Nox4 colocalizes with TRPV1 in sensory fibers of the renal pelvis, indicating that H2O2 generated from Nox4 may affect TRPV1 activity. Stepwise increases in IPP and saline loading resulted in H2O2 and SP release, sensory activation, diuresis, and natriuresis. These effects, however, were remarkably attenuated by Nox inhibition. Overall, these results suggest that Nox4-positive fibers liberate H2O2 after mechanostimulation, thereby contributing to a renal sensory nerve-mediated diuretic/natriuretic response.
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Affiliation(s)
- Chian-Shiung Lin
- Department of Surgery, Liou-Ying Hospital, Chi-Mei Medical Center, Tainan Hsien, Taiwan
| | - Shang-Hsing Lee
- Department of Urology, Cardinal Tien Hospital, New Taipei, Taiwan
| | - Ho-Shiang Huang
- Department of Urology, National Cheng Kung University, Tainan, Taiwan
| | - Yih-Sharng Chen
- Department of Cardiovascular Surgery, National Taiwan University Hospital, Taipei, Taiwan; and
| | - Ming-Chieh Ma
- School of Medicine, Fu-Jen Catholic University, New Taipei, Taiwan
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16
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Short-Term High Fat Intake Does Not Significantly Alter Markers of Renal Function or Inflammation in Young Male Sprague-Dawley Rats. J Nutr Metab 2015; 2015:157520. [PMID: 26185688 PMCID: PMC4491386 DOI: 10.1155/2015/157520] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 06/08/2015] [Accepted: 06/09/2015] [Indexed: 12/21/2022] Open
Abstract
Chronic high fat feeding is correlated with diabetes and kidney disease. However, the impact of short-term high fat diets (HFD) is not well-understood. Six weeks of HFD result in indices of metabolic syndrome (increased adiposity, hyperglycemia, hyperinsulinemia, hyperlipidemia, hyperleptinemia, and impaired endothelium-dependent vasodilation) compared to rats fed on standard chow. The hypothesis was that short-term HFD would induce early signs of renal disease. Young male Sprague-Dawley rats were fed either HFD (60% fat) or standard chow (5% fat) for six weeks. Morphology was determined by measuring changes in renal mass and microstructure. Kidney function was measured by analyzing urinary protein, creatinine, and hydrogen peroxide (H2O2) concentrations, as well as plasma cystatin C concentrations. Renal damage was measured through assessment of urinary oxDNA/RNA concentrations as well as renal lipid peroxidation, tumor necrosis factor alpha (TNFα), and interleukin 6 (IL-6). Despite HFD significantly increasing adiposity and renal mass, there was no evidence of early stage kidney disease as measured by changes in urinary and plasma biomarkers as well as histology. These findings suggest that moderate hyperglycemia and inflammation produced by short-term HFD are not sufficient to damage kidneys or that the ketogenic HFD may have protective effects within the kidneys.
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Monzon CM, Garvin JL. Nitric oxide decreases the permselectivity of the paracellular pathway in thick ascending limbs. Hypertension 2015; 65:1245-50. [PMID: 25895589 DOI: 10.1161/hypertensionaha.115.05356] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 03/19/2015] [Indexed: 12/22/2022]
Abstract
Thick ascending limbs reabsorb 25% to 30% of the filtered NaCl. About 50% to 70% is reabsorbed via the transcellular pathway and 30% to 50% is reabsorbed through the Na-selective paracellular pathway. Nitric oxide (NO) inhibits transepithelial Na reabsorption, but its effects on the paracellular pathway are unknown. We hypothesized that NO decreases the selectivity of the paracellular pathway in thick ascending limbs via cGMP-dependent protein kinase. To assess relative Na/Cl permeability ratios (PNa/PCl), we perfused rat thick ascending limbs and measured the effect of reducing bath NaCl on transepithelial voltage, creating dilution potentials, with vehicle, NO donors, and endogenous NO. PNa/PCl was calculated using the Goldman-Hodgkin-Katz equation. Reducing bath Na/Cl to 16/8, 32/24, and 64/56 mmol/L created dilution potentials of -13.6±2.2, -10.8±3.0, and -6.1±0.9 mV, respectively. Calculated PNa/PCls were 2.0±0.2, 2.2±0.5, and 1.9±0.2. The NO donor spermine NONOate (200 µmol/L) blunted the dilution potential caused by 32/24 mmol/L Na/Cl from -11.1±2.1 to -6.5±1.6 mV (P<0.004) and PNa/PCl from 2.2±0.4 to 1.5±0.2. Nitroglycerin (200 µmol/L), another NO donor, also reduced PNa/PCl. Controls showed no significant changes. Dibutyryl-cGMP decreased dilution potentials from -13.4±2.9 to -7.5±1.8 mV (n=6; P<0.01). cGMP-dependent protein kinase inhibition with KT5823 (4 µmol/L) blocked the effect of spermine NONOate, whereas phosphodiesterase 2 inhibition did not. Endogenously produced NO mimicked the effect of the NO donors. In conclusion, NO reduces the selectivity of the paracellular pathway in thick ascending limbs via cGMP and cGMP-dependent protein kinase.
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Affiliation(s)
- Casandra M Monzon
- From the Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH
| | - Jeffrey L Garvin
- From the Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH.
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18
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Abstract
Intrarenal autoregulatory mechanisms maintain renal blood flow (RBF) and glomerular filtration rate (GFR) independent of renal perfusion pressure (RPP) over a defined range (80-180 mmHg). Such autoregulation is mediated largely by the myogenic and the macula densa-tubuloglomerular feedback (MD-TGF) responses that regulate preglomerular vasomotor tone primarily of the afferent arteriole. Differences in response times allow separation of these mechanisms in the time and frequency domains. Mechanotransduction initiating the myogenic response requires a sensing mechanism activated by stretch of vascular smooth muscle cells (VSMCs) and coupled to intracellular signaling pathways eliciting plasma membrane depolarization and a rise in cytosolic free calcium concentration ([Ca(2+)]i). Proposed mechanosensors include epithelial sodium channels (ENaC), integrins, and/or transient receptor potential (TRP) channels. Increased [Ca(2+)]i occurs predominantly by Ca(2+) influx through L-type voltage-operated Ca(2+) channels (VOCC). Increased [Ca(2+)]i activates inositol trisphosphate receptors (IP3R) and ryanodine receptors (RyR) to mobilize Ca(2+) from sarcoplasmic reticular stores. Myogenic vasoconstriction is sustained by increased Ca(2+) sensitivity, mediated by protein kinase C and Rho/Rho-kinase that favors a positive balance between myosin light-chain kinase and phosphatase. Increased RPP activates MD-TGF by transducing a signal of epithelial MD salt reabsorption to adjust afferent arteriolar vasoconstriction. A combination of vascular and tubular mechanisms, novel to the kidney, provides for high autoregulatory efficiency that maintains RBF and GFR, stabilizes sodium excretion, and buffers transmission of RPP to sensitive glomerular capillaries, thereby protecting against hypertensive barotrauma. A unique aspect of the myogenic response in the renal vasculature is modulation of its strength and speed by the MD-TGF and by a connecting tubule glomerular feedback (CT-GF) mechanism. Reactive oxygen species and nitric oxide are modulators of myogenic and MD-TGF mechanisms. Attenuated renal autoregulation contributes to renal damage in many, but not all, models of renal, diabetic, and hypertensive diseases. This review provides a summary of our current knowledge regarding underlying mechanisms enabling renal autoregulation in health and disease and methods used for its study.
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Affiliation(s)
- Mattias Carlström
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Christopher S Wilcox
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - William J Arendshorst
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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Cowley AW, Abe M, Mori T, O'Connor PM, Ohsaki Y, Zheleznova NN. Reactive oxygen species as important determinants of medullary flow, sodium excretion, and hypertension. Am J Physiol Renal Physiol 2014; 308:F179-97. [PMID: 25354941 DOI: 10.1152/ajprenal.00455.2014] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The physiological evidence linking the production of superoxide, hydrogen peroxide, and nitric oxide in the renal medullary thick ascending limb of Henle (mTAL) to regulation of medullary blood flow, sodium homeostasis, and long-term control of blood pressure is summarized in this review. Data obtained largely from rats indicate that experimentally induced elevations of either superoxide or hydrogen peroxide in the renal medulla result in reduction of medullary blood flow, enhanced Na(+) reabsorption, and hypertension. A shift in the redox balance between nitric oxide and reactive oxygen species (ROS) is found to occur naturally in the Dahl salt-sensitive (SS) rat model, where selective reduction of ROS production in the renal medulla reduces salt-induced hypertension. Excess medullary production of ROS in SS rats emanates from the medullary thick ascending limbs of Henle [from both the mitochondria and membrane NAD(P)H oxidases] in response to increased delivery and reabsorption of excess sodium and water. There is evidence that ROS and perhaps other mediators such as ATP diffuse from the mTAL to surrounding vasa recta capillaries, resulting in medullary ischemia, which thereby contributes to hypertension.
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Affiliation(s)
- Allen W Cowley
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Michiaki Abe
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Takefumi Mori
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Paul M O'Connor
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Yusuke Ohsaki
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
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20
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Gomez SI, Mihos CG, Pineda AM, Santana O. The pleiotropic effects of the hydroxy-methyl-glutaryl-CoA reductase inhibitors in renal disease. Int J Nephrol Renovasc Dis 2014; 7:123-30. [PMID: 24729724 PMCID: PMC3974687 DOI: 10.2147/ijnrd.s55102] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
It is well known that statins exert their main effect by inhibiting cholesterol synthesis through the inhibition of the 3-hydroxy-3-methyl-glutaryl-CoA reductase enzyme. The pleiotropic effects of statins, which are independent of their inhibition of cholesterol synthesis, have explained many of the beneficial effects of these drugs in a variety of disorders such as malignancies, infection, and sepsis, as well as in cardiovascular and rheumatologic disorders. However, the role of these drugs in renal disorders remains controversial. In the present review, we examine the most recent findings involving statins and renal disease among different clinical scenarios, including chronic kidney disease, contrast-induced nephropathy, renal injury after coronary artery bypass surgery, and renal transplant patients.
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Affiliation(s)
- Sabas I Gomez
- Department of Internal Medicine, Mount Sinai Medical Center, Miami Beach, FL, USA
| | - Christos G Mihos
- Columbia University Division of Cardiology, Mount Sinai Heart Institute, Miami Beach, FL, USA
| | - Andres M Pineda
- Columbia University Division of Cardiology, Mount Sinai Heart Institute, Miami Beach, FL, USA
| | - Orlando Santana
- Columbia University Division of Cardiology, Mount Sinai Heart Institute, Miami Beach, FL, USA
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21
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Moss R, Layton AT. Dominant factors that govern pressure natriuresis in diuresis and antidiuresis: a mathematical model. Am J Physiol Renal Physiol 2014; 306:F952-69. [PMID: 24553433 DOI: 10.1152/ajprenal.00500.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
We have developed a whole kidney model of the urine concentrating mechanism and renal autoregulation. The model represents the tubuloglomerular feedback (TGF) and myogenic mechanisms, which together affect the resistance of the afferent arteriole and thus glomerular filtration rate. TGF is activated by fluctuations in macula densa [Cl(-)] and the myogefnic mechanism by changes in hydrostatic pressure. The model was used to investigate the relative contributions of medullary blood flow autoregulation and inhibition of transport in the proximal convoluted tubule to pressure natriuresis in both diuresis and antidiuresis. The model predicts that medullary blood flow autoregulation, which only affects the interstitial solute composition in the model, has negligible influence on the rate of NaCl excretion. However, it exerts a significant effect on urine flow, particularly in the antidiuretic kidney. This suggests that interstitial washout has significant implications for the maintenance of hydration status but little direct bearing on salt excretion, and that medullary blood flow may only play a signaling role for stimulating a pressure-natriuresis response. Inhibited reabsorption in the model proximal convoluted tubule is capable of driving pressure natriuresis when the known actions of vasopressin on the collecting duct epithelium are taken into account.
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Affiliation(s)
- Robert Moss
- Dept. of Mathematics, Duke Univ., Box 90320, Durham, NC 27708-0320.
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Abstract
SIGNIFICANCE Renal oxidative stress can be a cause, a consequence, or more often a potentiating factor for hypertension. Increased reactive oxygen species (ROS) in the kidney have been reported in multiple models of hypertension and related to renal vasoconstriction and alterations of renal function. Nicotinamide adenine dinucleotide phosphate oxidase is the central source of ROS in the hypertensive kidney, but a defective antioxidant system also can contribute. RECENT ADVANCES Superoxide has been identified as the principal ROS implicated for vascular and tubular dysfunction, but hydrogen peroxide (H2O2) has been implicated in diminishing preglomerular vascular reactivity, and promoting medullary blood flow and pressure natriuresis in hypertensive animals. CRITICAL ISSUES AND FUTURE DIRECTIONS Increased renal ROS have been implicated in renal vasoconstriction, renin release, activation of renal afferent nerves, augmented contraction, and myogenic responses of afferent arterioles, enhanced tubuloglomerular feedback, dysfunction of glomerular cells, and proteinuria. Inhibition of ROS with antioxidants, superoxide dismutase mimetics, or blockers of the renin-angiotensin-aldosterone system or genetic deletion of one of the components of the signaling cascade often attenuates or delays the onset of hypertension and preserves the renal structure and function. Novel approaches are required to dampen the renal oxidative stress pathways to reduced O2(-•) rather than H2O2 selectivity and/or to enhance the endogenous antioxidant pathways to susceptible subjects to prevent the development and renal-damaging effects of hypertension.
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Affiliation(s)
- Magali Araujo
- Hypertension, Kidney and Vascular Research Center, Georgetown University , Washington, District of Columbia
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Terawaki H, Zhu WJ, Matsuyama Y, Terada T, Takahashi Y, Sakurai K, Kabayama S, Miyazaki M, Itami N, Nakazawa R, Ito S, Era S, Nakayama M. Effect of a hydrogen (H2)-enriched solution on the albumin redox of hemodialysis patients. Hemodial Int 2013; 18:459-66. [PMID: 24274030 DOI: 10.1111/hdi.12112] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Elevated oxidative stress (OS) is associated with severe cardiovascular disease and premature death among patients treated with hemodialysis (HD). Oxidative stress is enhanced by contact between blood and dialysis membranes during HD sessions. This study aimed to clarify whether hydrogen (H2), which is a known antioxidant, is capable of suppressing increased OS induced during HD sessions. Eight patients on regular HD treatment were studied. Two HD sessions were performed in a cross-over design trial using standard and hydrogen-enriched solutions (mean of 50 p.p.b. H2; H2-HD). Blood samples were obtained from the inlet and outlet of the dialyzer during HD to determine changes in plasma levels of glutathione, hydrogen peroxide, and albumin redox state as a marker of OS. Comparison of inlet and outlet blood revealed significant decreases in total glutathione and reduced glutathione, as well as significant increases in hydrogen peroxide in both HD treatments. However, the mean proportion of reversibly oxidized albumin in outlet serum was significantly lower than that in inlet serum following the H2-HD session, whereas no significant changes were found in the standard solution session, suggesting that "intra-dialyzer" OS is reduced by H2 -HD. In conclusion, the application of H2-enriched solutions could ameliorate OS during HD.
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Impaired pressure natriuresis is associated with interstitial inflammation in salt-sensitive hypertension. Curr Opin Nephrol Hypertens 2013; 22:37-44. [PMID: 23165109 DOI: 10.1097/mnh.0b013e32835b3d54] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
PURPOSE OF REVIEW Impairment of the pressure natriuresis relationship is a central event in the pathogenesis of hypertension. Renal tubulointerstitial inflammation results in salt-sensitive hypertension and, until recently, the changes in pressure natriuresis induced by renal inflammation received little attention. RECENT FINDINGS Oxidative stress and increased intrarenal angiotensin II activity, in association with rarefaction and loss of peritubular vascular network, may be involved in the inflammation-induced blunting of the natriuresis resulting from increments in renal perfusion pressure. SUMMARY Here, we review the mechanisms for the impairment in pressure natriuresis resulting from renal tubulointerstitial inflammation in reference to the normal physiologic mechanisms involved in this response.
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Pavlov TS, Levchenko V, O'Connor PM, Ilatovskaya DV, Palygin O, Mori T, Mattson DL, Sorokin A, Lombard JH, Cowley AW, Staruschenko A. Deficiency of renal cortical EGF increases ENaC activity and contributes to salt-sensitive hypertension. J Am Soc Nephrol 2013; 24:1053-62. [PMID: 23599382 DOI: 10.1681/asn.2012080839] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Various stimuli, including hormones and growth factors, modulate epithelial sodium channels (ENaCs), which fine-tune Na(+) absorption in the kidney. Members of the EGF family are important for maintaining transepithelial Na(+) transport, but whether EGF influences ENaC, perhaps mediating salt-sensitive hypertension, is not well understood. Here, the ENaC inhibitor benzamil attenuated the development of hypertension in Dahl salt-sensitive rats. Feeding these salt-sensitive rats a high-salt diet led to lower levels of EGF in the kidney cortex and enhanced the expression and activity of ENaC compared with feeding a low-salt diet. To directly evaluate the role of EGF in the development of hypertension and its effect on ENaC activity, we infused EGF intravenously while continuously monitoring BP of the salt-sensitive rats. Infusion of EGF decreased ENaC activity, prevented the development of hypertension, and attenuated glomerular and renal tubular damage. Taken together, these findings indicate that cortical EGF levels decrease with a high-salt diet in salt-sensitive rats, promoting ENaC-mediated Na(+) reabsorption in the collecting duct and the development of hypertension.
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Affiliation(s)
- Tengis S Pavlov
- Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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Carbonyl stress induces hypertension and cardio-renal vascular injury in Dahl salt-sensitive rats. Hypertens Res 2013; 36:361-7. [PMID: 23364337 PMCID: PMC3619051 DOI: 10.1038/hr.2012.204] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
One major precursor of carbonyl stress, methylglyoxal (MG), is elevated in the plasma of chronic kidney disease (CKD) patients, and this precursor contributes to the progression of vascular injury, hypertension and renal injury in diabetic nephropathy patients. This molecule induces salt-sensitive hypertension via a reactive oxygen species-mediated pathway. We examined the role of MG in the pathogenesis of hypertension and cardio–renal injury in Dahl salt-sensitive (Dahl S) rats, which is a rat model of CKD. Nine-week-old Dahl S rats were fed a 1% NaCl diet, and 1% MG was added to their drinking water for up to 12 weeks. Blood pressure and cardio–renal injuries were compared with rats treated with tap water alone. The angiotensin II receptor blocker (ARB), candesartan (10 mg kg−1 day−1), was administered to MG Dahl S rats to determine the impact of this drug on the pathogenesis of MG-induced CKD. A progressive increase in systolic blood pressure was observed (123±1–148±5 mm Hg) after 12 weeks of MG administration. MG administration significantly increased urinary albumin excretion, glomerular sclerosis, tubular injury, myocardial collagen content and cardiac perivascular fibrosis. MG also enhanced the renal expression of Nɛ-carboxyethyl-lysine (an advanced glycation end product), 8-hydroxydeoxyguanosine (a marker of oxidative stress), macrophage (ED-1) positive cells (a marker of inflammation) and nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase activity. Candesartan treatment for 4 weeks significantly reduced these parameters. These results suggest that MG-induced hypertension and cardio–renal injury and increased inflammation and carbonyl and oxidative stress, which were partially preventable by an ARB.
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Albuminuria indicates the pressure-associated injury of juxtamedullary nephrons and cerebral strain vessels in spontaneously hypertensive stroke-prone rats. Hypertens Res 2012; 35:1024-31. [PMID: 22914555 PMCID: PMC3466437 DOI: 10.1038/hr.2012.112] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Albuminuria is an indicator of renal injury and is closely linked with cardiovascular disease (CVD). However, the mechanism by which albumin is excreted in the urine remains unclear. As the juxtamedullary region of the kidney is highly susceptible to pressure increase, juxtamedullary injury is observed from an early phase in hypertensive rat models. Anatomical similarities are observed between the pre-glomerular vessels of the juxtamedullary nephron and the cerebral vasculature. We previously named these ‘strain vessels' for their high vascular tone and exposure to higher pressures. The current studies were designed to determine whether albuminuria is the result of juxtamedullary nephron injury, indicating the presence of pressure injury to the strain vessels in spontaneously hypertensive stroke-prone rats (SHR-SP) fed a high-salt diet. Albuminuria was associated with juxtamedullary nephron injury, and the enhanced expression of monocyte chemotactic protein-1 (MCP-1) and tumor growth factor-beta (TGF-β) in 12-week-old SHR-SP rats fed a 4% high-salt diet from the age of 6 weeks. The wall thickness of the pre-glomerular vessels of the juxtamedullary nephron was also associated with that of the perforating artery of the middle cerebral artery. Reducing the blood pressure with nifedipine reduced the degree of albuminuria and juxtamedullary nephron injury as well as MCP-1 and TGF-β expression in the SHR-SP rats fed an 8% high-salt diet from the age of 9 weeks. Nifedipine inhibited stroke events in these animals until they were 14 weeks old. These results indicate that albuminuria is a result of juxtamedullary nephron injury and a marker of pressure-induced injury of the strain vessels.
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Role of specific T-type calcium channel blocker R(−) efonidipine in the regulation of renal medullary circulation. J Hypertens 2012; 30:1620-31. [DOI: 10.1097/hjh.0b013e3283550e9f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Feng D, Yang C, Geurts AM, Kurth T, Liang M, Lazar J, Mattson DL, O'Connor PM, Cowley AW. Increased expression of NAD(P)H oxidase subunit p67(phox) in the renal medulla contributes to excess oxidative stress and salt-sensitive hypertension. Cell Metab 2012; 15:201-8. [PMID: 22326221 PMCID: PMC3280886 DOI: 10.1016/j.cmet.2012.01.003] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 12/15/2011] [Accepted: 01/06/2012] [Indexed: 12/15/2022]
Abstract
NAD(P)H oxidase has been shown to be important in the development of salt-sensitive hypertension. Here, we show that the expression of a subunit of NAD(P)H oxidase, p67(phox), was increased in response to a high-salt diet in the outer renal medulla of the Dahl salt-sensitive (SS) rat, an animal model for human salt-sensitive hypertension. The higher expression of p67(phox), not the other subunits observed, was associated with higher NAD(P)H oxidase activity and salt sensitivity in SS rats compared with a salt-resistant strain. Genetic mutations of the SS allele of p67(phox) were found in the promoter region and contributed to higher promoter activity than that of the salt-resistant strain. To verify the importance of p67(phox), we disrupted p67(phox) in SS rats using zinc-finger nucleases. These rats exhibited a significant reduction of salt-sensitive hypertension and renal medullary oxidative stress and injury. p67(phox) could represent a target for salt-sensitive hypertension therapy.
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Affiliation(s)
- Di Feng
- Physiology Department, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Contribution of cytochrome P450 1B1 to hypertension and associated pathophysiology: a novel target for antihypertensive agents. Prostaglandins Other Lipid Mediat 2011; 98:69-74. [PMID: 22210049 DOI: 10.1016/j.prostaglandins.2011.12.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 11/18/2011] [Accepted: 12/12/2011] [Indexed: 12/24/2022]
Abstract
The aim of this review is to discuss the contribution of cytochrome P450 (CYP) 1B1 in vascular smooth muscle cell growth, hypertension, and associated pathophysiology. CYP1B1 is expressed in cardiovascular and renal tissues, and mediates angiotensin II (Ang II)-induced activation of NADPH oxidase and generation of reactive oxygen species (ROS), and vascular smooth muscle cell migration, proliferation, and hypertrophy. Moreover, CYP1B1 contributes to the development and/or maintenance of hypertension produced by Ang II-, deoxycorticosterone (DOCA)-salt-, and N(ω)-nitro-L-arginine methyl ester-induced hypertension and in spontaneously hypertensive rats. The pathophysiological changes, including cardiovascular hypertrophy, increased vascular reactivity, endothelial and renal dysfunction, injury and inflammation associated with Ang II- and/or DOCA-salt induced hypertension in rats, and Ang II-induced hypertension in mice are minimized by inhibition of CYP1B1 activity with 2,4,3',5'-tetramethoxystilbene or by Cyp1b1 gene disruption in mice. These pathophysiological changes appear to be mediated by increased production of ROS via CYP1B1-dependent NADPH oxidase activity and extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase, and c-Src.
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Jennings BL, Anderson LJ, Estes AM, Yaghini FA, Fang XR, Porter J, Gonzalez FJ, Campbell WB, Malik KU. Cytochrome P450 1B1 contributes to renal dysfunction and damage caused by angiotensin II in mice. Hypertension 2011; 59:348-54. [PMID: 22184325 DOI: 10.1161/hypertensionaha.111.183301] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Cytochrome P450 1B1 contributes to the development of angiotensin II-induced hypertension and associated cardiovascular pathophysiology. In view of the critical role of angiotensin II in the kidney, as well as in salt and water homeostasis, and blood pressure regulation, we determined the contribution of cytochrome P450 1B1 to renal dysfunction and injury associated with angiotensin II-induced hypertension in male Cyp1b1(+/+) and Cyp1b1(-/-) mice. Angiotensin II infusion (700 ng/kg per minute) given by miniosmotic pumps for 13 and 28 days increased systolic blood pressure in Cyp1b1(+/+) mice; this increase was significantly reduced in Cyp1b1(-/-) mice. Angiotensin II increased renal Cyp1b1 activity, vascular resistance, and reactivity to vasoconstrictor agents and caused endothelial dysfunction in Cyp1b1(+/+) but not Cyp1b1(-/-) mice. Angiotensin II increased water consumption and urine output, decreased urine osmolality, increased urinary Na(+) and K(+) excretion, and caused proteinuria and albuminuria in Cyp1b1(+/+) mice that was diminished in Cyp1b1(-/-) mice. Infusion of angiotensin II for 28 but not 13 days caused renal fibrosis, tubular damage, and inflammation in Cyp1b1(+/+) mice, which was minimized in Cyp1b1(-/-) mice. Angiotensin II increased levels of 12- and 20-hydroxyeicosatetraenoic acids; reactive oxygen species; and activity of NADPH oxidase, extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase, and c-Src in the kidneys of Cyp1b1(+/+) but not Cyp1b1(-/-) mice. These data suggest that increased thirst, renal dysfunction, and injury and inflammation associated with angiotensin II-induced hypertension in mice depend on cytochrome P450 1B1 activity, thus indicating that cytochrome P450 1B1 could serve as a novel target for treating renal disease and hypertension.
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Affiliation(s)
- Brett L Jennings
- Department of Pharmacology, College of Medicine, 874 Union Ave, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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Jennings BL, Anderson LJ, Estes AM, Fang XR, Song CY, Campbell WB, Malik KU. Involvement of cytochrome P-450 1B1 in renal dysfunction, injury, and inflammation associated with angiotensin II-induced hypertension in rats. Am J Physiol Renal Physiol 2011; 302:F408-20. [PMID: 22088434 DOI: 10.1152/ajprenal.00542.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We investigated the contribution of cytochrome P-450 1B1 (CYP1B1) to renal dysfunction and organ damage associated with ANG II-induced hypertension in rats. ANG II (300 ng·kg(-1)·min(-1)) or vehicle were infused for 2 wk, with daily injections of a selective CYP1B1 inhibitor, 2,4,3',5'-tetramethoxystilbene (TMS; 300 μg/kg ip), or its vehicle. ANG II increased blood pressure and renal CYP1B1 activity that were prevented by TMS. ANG II also increased water intake and urine output, decreased glomerular filtration rate, increased urinary Na(+) and K(+) excretion, and caused proteinuria, all of which were prevented by TMS. ANG II infusion caused hypertrophy, endothelial dysfunction, and increased reactivity of renal and interlobar arteries to vasoconstrictor agents and renal vascular resistance and interstitial fibrosis as indicated by accumulation of α-smooth muscle actin, fibronectin, and collagen, and inflammation as indicated by increased infiltration of CD-3(+) cells; these effects were inhibited by TMS. ANG II infusion also increased production of reactive oxygen species (ROS) and activities of NADPH oxidase, ERK1/2, p38 MAPK, and c-Src that were prevented by TMS. TMS alone had no effect on any of the above parameters. These data suggest that CYP1B1 contributes to the renal pathophysiological changes associated with ANG II-induced hypertension, most likely via increased ROS production and activation of ERK1/2, p38 MAPK, and c-Src and that CYP1B1 could serve as a novel target for treating renal disease associated with hypertension.
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Affiliation(s)
- Brett L Jennings
- Dept. of Pharmacology, College of Medicine, Univ. of Tennessee Health Science Center, 874 Union Ave., Memphis, TN 38163, USA
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Warner L, Yin M, Glaser KJ, Woollard JA, Carrascal CA, Korsmo MJ, Crane JA, Ehman RL, Lerman LO. Noninvasive In vivo assessment of renal tissue elasticity during graded renal ischemia using MR elastography. Invest Radiol 2011; 46:509-14. [PMID: 21467945 PMCID: PMC3128234 DOI: 10.1097/rli.0b013e3182183a95] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVES : Magnetic resonance elastography (MRE) allows noninvasive assessment of tissue stiffness in vivo. Renal arterial stenosis (RAS), a narrowing of the renal artery, promotes irreversible tissue fibrosis that threatens kidney viability and may elevate tissue stiffness. However, kidney stiffness may also be affected by hemodynamic factors. This study tested the hypothesis that renal blood flow (RBF) is an important determinant of renal stiffness as measured by MRE. MATERIAL AND METHODS : In 6 anesthetized pigs MRE studies were performed to determine cortical and medullary elasticity during acute graded decreases in RBF (by 20%, 40%, 60%, 80%, and 100% of baseline) achieved by a vascular occluder. Three sham-operated swine served as time control. Additional pigs were studied with MRE 6 weeks after induction of chronic unilateral RAS (n = 6) or control (n = 3). Kidney fibrosis was subsequently evaluated histologically by trichrome staining. RESULTS : During acute RAS the stenotic cortex stiffness decreased (from 7.4 ± 0.3 to 4.8 ± 0.6 kPa, P = 0.02 vs. baseline) as RBF decreased. Furthermore, in pigs with chronic RAS (80% ± 5.4% stenosis) in which RBF was decreased by 60% ± 14% compared with controls, cortical stiffness was not significantly different from normal (7.4 ± 0.3 vs. 7.6 ± 0.3 kPa, P = 0.3), despite histologic evidence of renal tissue fibrosis. CONCLUSION : Hemodynamic variables modulate kidney stiffness measured by MRE and may mask the presence of fibrosis. These results suggest that kidney turgor should be considered during interpretation of elasticity assessments.
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Affiliation(s)
- Lizette Warner
- The Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Meng Yin
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Kevin J. Glaser
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - John A. Woollard
- The Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Michael J. Korsmo
- The Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - John A. Crane
- The Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Lilach O. Lerman
- The Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
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O'Connor PM, Cowley AW. Modulation of pressure-natriuresis by renal medullary reactive oxygen species and nitric oxide. Curr Hypertens Rep 2011; 12:86-92. [PMID: 20424940 DOI: 10.1007/s11906-010-0094-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The renal pressure-natriuresis mechanism is the dominant controller of body fluid balance and long-term arterial pressure. In recent years, it has become clear that the balance of reactive oxygen and nitrogen species within the renal medullary region is a key determinant of the set point of the renal pressure-natriuresis curve. The development of renal medullary oxidative stress causes dysfunction of the pressure-natriuresis mechanism and contributes to the development of hypertension in numerous disease models. The purpose of this review is to point out the known mechanisms within the renal medulla through which reactive oxygen and nitrogen species modulate the pressure-natriuresis response and to update the reader on recent advances in this field.
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Affiliation(s)
- Paul M O'Connor
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53202, USA.
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Endogenous hydrogen peroxide up-regulates the expression of nitric oxide synthase in the kidney of SHR. J Hypertens 2011; 29:1167-74. [DOI: 10.1097/hjh.0b013e3283468367] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Moment-to-Moment Characteristics of the Relationship Between Arterial Pressure and Renal Interstitial Hydrostatic Pressure. Hypertension 2010; 56:650-7. [DOI: 10.1161/hypertensionaha.109.149633] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Polichnowski AJ, Jin C, Yang C, Cowley AW. Role of renal perfusion pressure versus angiotensin II on renal oxidative stress in angiotensin II-induced hypertensive rats. Hypertension 2010; 55:1425-30. [PMID: 20404214 DOI: 10.1161/hypertensionaha.110.151332] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Renal oxidative stress is thought to contribute to both the etiology and the associated renal injury in angiotensin (Ang) II-dependent hypertension. The contribution of Ang II versus elevated renal perfusion pressure (RPP) on albuminuria and renal oxidative stress in this model of hypertension was explored in the present study by chronically servocontrolling RPP to the left kidney and comparing responses with the right uncontrolled kidney and the left kidney of sham rats. Hypertension was produced in Sprague-Dawley rats fed a 4% NaCl diet by chronic IV infusion of Ang II (25 ng/kg per minute). The RPP to the left kidney was servocontrolled to mean daily pressures averaging approximately 120 mm Hg, whereas the uncontrolled kidneys averaged approximately 170 mm Hg over 14 days of Ang II infusion. Ang II infusion resulted in a 2.4-fold increase in albuminuria, which was RPP dependent. Kidneys exposed to both elevated RPP and Ang II (uncontrolled kidneys) displayed a 3.5-fold increase in malondialdehyde excretion and a 37% and 27% increase in renal cortical and outer medullary superoxide production, respectively. Elevated RPP significantly contributed to global renal oxidative stress (70% increase in malondialdehyde excretion) and outer medullary superoxide production. Elevated circulating levels of Ang II, per se, were responsible for a 1.5-fold and 2.0-fold increase in renal cortical and outer medullary NADPH oxidase activity, respectively. In summary, this study demonstrates that elevated RPP is directly responsible for the excess albuminuria in Ang II-infused rats, whereas both elevated RPP and Ang II directly contribute to the observed renal oxidative stress.
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Affiliation(s)
- Aaron J Polichnowski
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Gongora MC, Harrison DG. NO solution for a radical problem: a TAL story. Am J Physiol Renal Physiol 2010; 298:F883-4. [DOI: 10.1152/ajprenal.00023.2010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Maria Carolina Gongora
- Department of Medicine and Division of Cardiology, Emory University School of Medicine and Atlanta Veterans Affairs Medical Center, Atlanta, Georgia
| | - David G. Harrison
- Department of Medicine and Division of Cardiology, Emory University School of Medicine and Atlanta Veterans Affairs Medical Center, Atlanta, Georgia
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Polichnowski AJ, Cowley AW. Pressure-induced renal injury in angiotensin II versus norepinephrine-induced hypertensive rats. Hypertension 2009; 54:1269-77. [PMID: 19858406 DOI: 10.1161/hypertensionaha.109.139287] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The susceptibility to renal perfusion pressure (RPP)-induced renal injury was investigated in angiotensin II (Ang II)- versus norepinephrine (NE)-infused hypertensive rats. To determine the magnitude of RPP-induced injury, Sprague-Dawley rats fed a 4% salt diet were instrumented with a servocontrolled aortic balloon occluder positioned between the renal arteries to maintain RPP to the left kidney at baseline levels whereas the right kidney was exposed to elevated RPP during a 2-week infusion of Ang II IV (25 ng/kg per minute), NE IV (0.5, 1.0, and 2.0 microg/kg per minute on days 1, 2, and 3 to 14, respectively), or saline IV (sham rats). Over the 14 days of Ang II infusion, RPP averaged 161.5+/-8.0 mm Hg to uncontrolled kidneys and 121.9+/-2.0 mm Hg to servocontrolled kidneys. In NE-infused rats, RPP averaged 156.3+/-3.0 mm Hg to uncontrolled kidneys and 116.9+/-2.0 mm Hg to servocontrolled kidneys. RPP averaged 111.1+/-1.0 mm Hg to kidneys of sham rats. Interlobular arterial injury and juxtamedullary glomerulosclerosis were largely RPP dependent in both models of hypertension. Superficial cortical glomerulosclerosis was greater and RPP dependent in NE- versus Ang II-infused rats, which was primarily independent of RPP. Outer medullary tubular necrosis and interstitial fibrosis were also primarily RPP dependent in both models of hypertension; however, the magnitude of injury was exacerbated in Ang II-infused rats. We conclude that elevated RPP is the dominant cause of renal injury in both NE- and Ang II-induced hypertensive rats and that underlying neurohumoral factors in these models of hypertension alter the pattern and magnitude of RPP-induced renal injury.
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Affiliation(s)
- Aaron J Polichnowski
- Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI 53226, USA
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