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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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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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Association between long-term pulse pressure trajectories and risk of end-stage renal diseases in incident malignant hypertensive nephropathy: a cohort study. Blood Press Monit 2021; 26:14-21. [PMID: 32740292 DOI: 10.1097/mbp.0000000000000477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The trajectories of pulse pressure (PP) might affect the prognosis of malignant hypertensive nephropathy (MHN). We aimed to describe the association between PP trajectories and the future risk of end-stage renal disease and to identify and compare the associated patient characteristics of any distinct trajectory patterns in MHN patients. METHODS Patients with newly diagnosed biopsy-proven MHN 2010-2015 were included. Latent class growth analysis was applied to the PP measured over 3 years prior to biopsy to identify distinct trajectories. Concurrent systolic blood pressure, diastolic blood pressure, plasma creatinine, and 24-h urine protein measurements for each trajectory group were modelled using generalized estimating equations. The risk of end-stage renal disease (with kidney replacement therapy as a proxy) was estimated using Logistic regression. RESULTS Two hundred three patients were included (median-age 34 years, and 19.7% female). A two-group cubic model was optimal, with trajectories distinguished by the rate of PP and absolute level at final measurement. Trajectory Group-1 (n = 84) was characterized by 'first-increased-then-decreased' PP and trajectory Group-2 (n = 119) was characterized by 'first-decreased-then-increased' PP over 3 years prior to biopsy. Systolic and diastolic blood pressures, plasma creatinine, and 24-h urine protein were differed by the trajectory group. Baseline characteristics differed substantially between trajectory groups. Compared with Group-1, Group-2 had a 66% greater risk of developing into end-stage renal disease in the subsequent 3 years. CONCLUSIONS Two distinct 3-year trajectories for PP exist with MHN. Early introduction of intensive antihypertensive treatment might delay the development of end-stage renal disease among patients with malignant hypertension.
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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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Leader CJ, Clark BJ, Hannah AR, Sammut IA, Wilkins GT, Walker RJ. Breeding Characteristics and Dose-dependent Blood Pressure Responses of Transgenic Cyp1a1-Ren2 Rats. Comp Med 2018; 68:360-366. [PMID: 30185285 DOI: 10.30802/aalas-cm-17-18000026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Hypertension is a leading risk factor for cardiovascular and chronic kidney disease. A new rodent model (transgenic male Cyp1a1-Ren2 rats) provides reversible induction of hypertension through the addition of indole-3-carbinol (I3C) to the diet, without the need for surgical intervention, thus giving researchers control over both the onset of hypertension and its magnitude (I3C dose-dependency). We here report the breeding performance and productivity of Cyp1a1-Ren2 rats. Despite being transgenic, these animals proved to be efficient breeders. In addition to confirming inducible and reversible dose-dependent hypertension (by using I3C doses of 0.125%, 0.167%, and 0.25% [w/w] in the diet for 14 d, followed by normal chow for 4 d), we demonstrated that hypertension can be sustained chronically (14 wk) by continuous dosing with I3C (0.167% [w/w]) in the diet. In chronically dosed male rats, systolic blood pressure continued to rise, from 173 ± 11 mm Hg after 1 mo to 196 ± 19 mm Hg after 3 mo, with no adverse phenotypic features observed. In conclusion, Cyp1a1-Ren2 rats are a useful animal model to investigate hypertension-induced end-organ damage and potential new therapeutic targets to manage hypertension.
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Affiliation(s)
| | - Barbara J Clark
- Hercus-Taieri Resource Unit, University of Otago, Dunedin, New Zealand
| | - Amber R Hannah
- Hercus-Taieri Resource Unit, University of Otago, Dunedin, New Zealand
| | - Ivan A Sammut
- Department of Pharmacology, University of Otago, Dunedin, New Zealand
| | - Gerard T Wilkins
- Department of Medicine, University of Otago, Dunedin, New Zealand
| | - Robert J Walker
- Department of Medicine, University of Otago, Dunedin, New Zealand
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Rodriguez R, Moreno M, Lee AY, Godoy-Lugo JA, Nakano D, Nishiyama A, Parkes D, Awayda MS, Ortiz RM. Simultaneous GLP-1 receptor activation and angiotensin receptor blockade increase natriuresis independent of altered arterial pressure in obese OLETF rats. Hypertens Res 2018; 41:798-808. [PMID: 29985448 DOI: 10.1038/s41440-018-0070-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 01/11/2018] [Accepted: 01/14/2018] [Indexed: 01/08/2023]
Abstract
Obesity is associated with an inappropriately activated renin-angiotensin-aldosterone system, suppressed glucagon-like peptide-1 (GLP-1), increased renal Na+ reabsorption, and hypertension. To assess the link between GLP-1 and angiotensin receptor type 1 (AT1) signaling on obesity-associated impairment of urinary Na+ excretion (UNaV) and elevated arterial pressure, we measured mean arterial pressure (MAP) and heart rate by radiotelemetry and metabolic parameters for 40 days. We tested the hypothesis that stimulation of GLP-1 signaling provides added benefit to blockade of AT1 by increasing UNaV and further reducing arterial pressure in the following groups: (1) untreated Long-Evans Tokushima Otsuka (LETO) rats (n = 7); (2) untreated Otsuka Long-Evans Tokushima Fatty (OLETF) rats (n = 9); (3) OLETF + ARB (ARB; 10 mg olmesartan/kg/day; n = 9); (4) OLETF + GLP-1 receptor agonist (EXE; 10 µg exenatide/kg/day; n = 7); and (5) OLETF + ARB + EXE (Combo; n = 6). On day 2, UNaV was 60% and 62% reduced in the EXE and Combo groups, respectively, compared with that in the OLETF rats. On day 40, UNaV was increased 69% in the Combo group compared with that in the OLETF group. On day 40, urinary angiotensinogen was 4.5-fold greater in the OLETF than in the LETO group and was 56%, 62%, and 58% lower in the ARB, EXE, and Combo groups, respectively, than in the OLETF group. From day 2 to the end of the study, MAP was lower in the ARB and Combo groups than in the OLETF rats. These results suggest that GLP-1 receptor activation may reduce intrarenal angiotensin II activity, and that simultaneous blockade of AT1 increases UNaV in obesity; however, these beneficial effects do not translate to a further reduction in MAP.
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Affiliation(s)
- Ruben Rodriguez
- Department of Molecular and Cellular Biology, University of California Merced, Merced, CA, USA.
| | - Meagan Moreno
- Department of Molecular and Cellular Biology, University of California Merced, Merced, CA, USA
| | - Andrew Y Lee
- Department of Molecular and Cellular Biology, University of California Merced, Merced, CA, USA
| | - Jose A Godoy-Lugo
- Department of Molecular and Cellular Biology, University of California Merced, Merced, CA, USA
| | - Daisuke Nakano
- Department of Pharmacology, Kagawa University Medical School, Kagawa, Japan
| | - Akira Nishiyama
- Department of Pharmacology, Kagawa University Medical School, Kagawa, Japan
| | | | - Mouhamed S Awayda
- Department of Physiology and Biophysics, University of Buffalo, Buffalo, NY, USA
| | - Rudy M Ortiz
- Department of Molecular and Cellular Biology, University of California Merced, Merced, CA, USA
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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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Minas JN, Thorwald MA, Conte D, Vázquez-Medina JP, Nishiyama A, Ortiz RM. Angiotensin and mineralocorticoid receptor antagonism attenuates cardiac oxidative stress in angiotensin II-infused rats. Clin Exp Pharmacol Physiol 2016; 42:1178-88. [PMID: 26234762 DOI: 10.1111/1440-1681.12473] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 06/30/2015] [Accepted: 06/30/2015] [Indexed: 11/30/2022]
Abstract
Angiotensin II (Ang II) and aldosterone contribute to hypertension, oxidative stress and cardiovascular damage, but the contributions of aldosterone during Ang II-dependent hypertension are not well defined because of the difficulty to assess each independently. To test the hypothesis that during Ang II infusion, oxidative and nitrosative damage is mediated through both the mineralocorticoid receptor (MR) and angiotensin type 1 receptor (AT1), five groups of Sprague-Dawley rats were studied: (i) control; (ii) Ang II infused (80 ng/min × 28 days); (iii) Ang II + AT1 receptor blocker (ARB; 10 mg losartan/kg per day × 21 days); (iv) Ang II + mineralocorticoid receptor (MR) antagonist (Epl; 100 mg eplerenone/day × 21 days); and (v) Ang II + ARB + Epl (Combo; × 21 days). Both ARB and combination treatments completely alleviated the Ang II-induced hypertension, whereas eplerenone treatment only prolonged the onset of the hypertension. Eplerenone treatment exacerbated the Ang II-mediated increase in plasma and heart aldosterone 2.3- and 1.8-fold, respectively, while ARB treatment reduced both. Chronic MR blockade was sufficient to ameliorate the AT1-mediated increase in oxidative damage. All treatments normalized protein oxidation (nitrotyrosine) levels; however, only ARB and Combo treatments completely reduced lipid peroxidation (4-hydroxynonenal) to control levels. Collectively, these data suggest that receptor signalling, and not the elevated arterial blood pressure, is the principal culprit in the oxidative stress-associated cardiovascular damage in Ang II-dependent hypertension.
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Affiliation(s)
- Jacqueline N Minas
- Molecular Cell Biology, School of Natural Sciences, University of California, Merced, CA, USA
| | - Max A Thorwald
- Molecular Cell Biology, School of Natural Sciences, University of California, Merced, CA, USA
| | - Debra Conte
- Molecular Cell Biology, School of Natural Sciences, University of California, Merced, CA, USA
| | | | - Akira Nishiyama
- Department of Pharmacology, Kagawa Medical University, Kagawa, Japan
| | - Rudy M Ortiz
- Molecular Cell Biology, School of Natural Sciences, University of California, Merced, CA, USA
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Sun QL, Li M, Rui HL, Chen YP. Inhibition of local aldosterone by eplerenone reduces renal structural damage in a novel model of chronic cyclosporine A nephrotoxicity. J Renin Angiotensin Aldosterone Syst 2014; 16:301-10. [PMID: 25500744 DOI: 10.1177/1470320314561248] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Accepted: 10/14/2014] [Indexed: 11/16/2022] Open
Affiliation(s)
- Qiao-Ling Sun
- Department of Nephrology, Qilu Hospital, Shandong University, China
| | - Meng Li
- Department of Neurosurgery, Qianfoshan Hospital, Shandong University, China
| | - Hong-Liang Rui
- Department of Nephrology, Beijing An Zhen Hospital, Capital Medical University, China
| | - Yi-Pu Chen
- Department of Nephrology, Beijing An Zhen Hospital, Capital Medical University, China
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Cunningham MW, Sasser JM, West CA, Milani CJ, Baylis C, Mitchell KD. Renal nitric oxide synthase and antioxidant preservation in Cyp1a1-Ren-2 transgenic rats with inducible malignant hypertension. Am J Hypertens 2013; 26:1242-9. [PMID: 23764378 DOI: 10.1093/ajh/hpt096] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Dietary administration of 0.30% indole-3-carbinol (I3C) to Cyp1a1-Ren2 transgenic rats (TGRs) generates angiotensin II (ANG II)-dependent malignant hypertension (HTN) and increased renal vascular resistance. However, TGRs with HTN maintain a normal or slightly reduced glomerular filtration rate. We tested the hypothesis that maintenance of renal function in hypertensive Cyp1a1-Ren2 TGRs is due to preservation of the intrarenal nitric oxide (NO) and antioxidant systems. METHODS Kidney cortex, kidney medulla, aortic endothelial (e) and neuronal (n) nitric oxide synthase (NOS), superoxide dismutases (SODs), and p22phox (nicotinamide adenine dinucleotide phosphate-oxidase subunit) protein abundances were measured along with kidney cortex total antioxidant capacity (TAC) and NOx. TGRs were fed a normal diet that contained 0.3% I3C or 0.3% I3C + candesartan (AT1 receptor antagonist; 25mg/L in drinking water) (n = 5-6 per group) for 10 days. RESULTS Blood pressure increased and body weight decreased in I3C-induced TGRs, while candesartan blunted these responses. Abundances of NOS, SOD, and p22phox as well as TAC were maintained in the kidney cortex of I3C-induced TGRs with and without candesartan, while kidney cortex NOx production increased in both groups. Kidney medulla eNOS and extracellular (EC) SOD decreased and nNOS were unchanged in both groups of I3C-induced TGRs. In addition, a compensatory increase occurred in kidney medulla Mn SOD in I3C-induced TGRs + candesartan. Aortic eNOS and nNOS∝ fell and p22phox and Mn SOD increased in hypertensive I3C-induced TGRs; all changes were reversed with candesartan. CONCLUSIONS The preservation of renal cortical NO and antioxidant capacity is associated with preserved renal function in Cyp1a1-Ren2 TGRs with ANG II-dependent malignant HTN.
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Affiliation(s)
- Mark W Cunningham
- Departments of Physiology and Medicine, University of Florida, Gainesville, Florida
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Increased sympathetic drive during the onset of hypertension in conscious Cyp1a1-Ren2 rats. Pflugers Arch 2013; 466:459-66. [DOI: 10.1007/s00424-013-1338-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 08/06/2013] [Accepted: 08/14/2013] [Indexed: 12/21/2022]
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Issa AT, Miyata K, Heng V, Mitchell KD, Derbenev AV. Increased neuronal activity in the OVLT of Cyp1a1-Ren2 transgenic rats with inducible Ang II-dependent malignant hypertension. Neurosci Lett 2012; 519:26-30. [PMID: 22579820 DOI: 10.1016/j.neulet.2012.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 04/27/2012] [Accepted: 05/02/2012] [Indexed: 11/27/2022]
Abstract
The contribution of angiotensin II (Ang II) to the pathophysiology of hypertension is established based on facts that high levels of circulating Ang II increase vasoconstriction of peripheral arteries causing a rise in blood pressure (BP). In addition, circulating Ang II has various effects on the central nervous system, including the osmosensitive neurons in the organum vasculosum of the lamina terminalis (OVLT). Osmosensitive neurons in the OVLT transduce hypertonicity via the activation of the nonselective cation channel known as transient receptor potential vanilloid 1 (TRPV1), causing membrane depolarization, followed by increased action potential discharge. This effect is absent in mice lacking expression of the TRPV1 gene. Most observations related to the importance of the OVLT in cardiovascular control are mainly based on models of lesion of the entire preoptic periventricular tissue. However, it remains unclear whether neuronal activity and TRPV1 protein expression levels alter in the OVLT of Cyp1a1-Ren2 transgenic rats with inducible Ang II-dependent malignant hypertension. C-fos was used as a marker of neuronal activity. Immunostaining was used to demonstrate distribution of c-fos positive neurons in the OVLT of Cyp1a1Ren2 transgenic rats. Western blot analysis showed increased c-fos and TRPV1 total protein expression levels in the OVLT of hypertensive rats. The present findings demonstrate increased c-fos and TRPV1 expression levels in the OVLT of Cyp1a1-Ren2 transgenic rats with Ang II-dependent malignant hypertension.
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Affiliation(s)
- Alexandra T Issa
- Department of Physiology, Tulane University, New Orleans, LA, United States
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Ashek A, Menzies RI, Mullins LJ, Bellamy COC, Harmar AJ, Kenyon CJ, Flatman PW, Mullins JJ, Bailey MA. Activation of thiazide-sensitive co-transport by angiotensin II in the cyp1a1-Ren2 hypertensive rat. PLoS One 2012; 7:e36311. [PMID: 22558431 PMCID: PMC3338649 DOI: 10.1371/journal.pone.0036311] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 04/02/2012] [Indexed: 12/02/2022] Open
Abstract
Transgenic rats with inducible expression of the mouse Ren2 gene were used to elucidate mechanisms leading to the development of hypertension and renal injury. Ren2 transgene activation was induced by administration of a naturally occurring aryl hydrocarbon, indole-3-carbinol (100 mg/kg/day by gastric gavage). Blood pressure and renal parameters were recorded in both conscious and anesthetized (butabarbital sodium; 120 mg/kg IP) rats at selected time-points during the development of hypertension. Hypertension was evident by the second day of treatment, being preceded by reduced renal sodium excretion due to activation of the thiazide-sensitive sodium-chloride co-transporter. Renal injury was evident after the first day of transgene induction, being initially limited to the pre-glomerular vasculature. Mircoalbuminuria and tubuloinsterstitial injury developed once hypertension was established. Chronic treatment with either hydrochlorothiazide or an AT1 receptor antagonist normalized sodium reabsorption, significantly blunted hypertension and prevented renal injury. Urinary aldosterone excretion was increased ∼20 fold, but chronic mineralocorticoid receptor antagonism with spironolactone neither restored natriuretic capacity nor prevented hypertension. Spironolactone nevertheless ameliorated vascular damage and prevented albuminuria. This study finds activation of sodium-chloride co-transport to be a key mechanism in angiotensin II-dependent hypertension. Furthermore, renal vascular injury in this setting reflects both barotrauma and pressure-independent pathways associated with direct detrimental effects of angiotensin II and aldosterone.
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Affiliation(s)
- Ali Ashek
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom
| | - Robert I. Menzies
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom
| | - Linda J. Mullins
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom
| | | | - Anthony J. Harmar
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom
| | - Christopher J. Kenyon
- University/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, United Kingdom
| | - Peter W. Flatman
- Centre for Integrative Physiology, The University of Edinburgh, Edinburgh, United Kingdom
| | - John J. Mullins
- University/British Heart Foundation Centre for Cardiovascular Science, 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
- * E-mail:
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Nakano D, Lei B, Kitada K, Hitomi H, Kobori H, Mori H, Deguchi K, Masaki T, Minamino T, Nishiyama A. Aldosterone does not contribute to renal p21 expression during the development of angiotensin II-induced hypertension in mice. Am J Hypertens 2012; 25:354-8. [PMID: 22113172 DOI: 10.1038/ajh.2011.224] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND We recently reported that aldosterone-induced cellular senescence via an increase in p21, a cyclin-dependent kinase (CDK) inhibitor, in rat kidney and cultured human proximal tubular cells. In the present study, we investigated the contribution of aldosterone to the renal p21 expression and senescence during the development of angiotensin II (AngII)-induced hypertension. METHODS Mice received 1% salt in drinking water and vehicle or AngII, and were divided into five groups: 1, vehicle; 2, AngII; 3, AngII+olmesartan; 4, AngII+eplerenone; and 5, AngII+hydralazine. RESULTS Plasma aldosterone levels were increased by AngII infusion. Eplerenone further elevated the plasma aldosterone level, but olmesartan and hydralazine did not. AngII group showed significant increase in blood pressure compared to vehicle. Olmesartan and hydralazine, but not eplerenone, suppressed the AngII-salt hypertension. The increase in urinary protein excretion by AngII-salt was suppressed only by olmesartan. AngII with high salt induced a greater expression of p21 mRNA in the kidney than vehicle. Olmesartan abolished the increase in p21 expression, whereas neither eplerenone nor hydralazine affected it. AngII with high salt did not change the expression of p16, another CDK inhibitor. The mice lacking p21 showed identical changes on blood pressure and albuminuria in response to AngII with high salt compared to wild type. CONCLUSION These results suggest that aldosterone does not predominantly contribute to renal p21 expression and senescence during the development of AngII-salt hypertension, and that the increase in p21 in the kidney is not likely involved in the development of hypertension and albuminuria.
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Whaley-Connell AT, Habibi J, Nistala R, DeMarco VG, Pulakat L, Hayden MR, Joginpally T, Ferrario CM, Parrish AR, Sowers JR. Mineralocorticoid receptor-dependent proximal tubule injury is mediated by a redox-sensitive mTOR/S6K1 pathway. Am J Nephrol 2011; 35:90-100. [PMID: 22205374 DOI: 10.1159/000335079] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 11/12/2011] [Indexed: 01/15/2023]
Abstract
BACKGROUND/AIMS The mammalian target of rapamycin (mTOR) is a serine kinase that regulates phosphorylation (p) of its target ribosomal S6 kinase (S6K1), whose activation can lead to glomerular and proximal tubular cell (PTC) injury and associated proteinuria. Increased mTOR/S6K1 signaling regulates signaling pathways that target fibrosis through adherens junctions. Recent data indicate aldosterone signaling through the mineralocorticoid receptor (MR) can activate the mTOR pathway. Further, antagonism of the MR has beneficial effects on proteinuria that occur independent of hemodynamics. METHODS Accordingly, hypertensive transgenic TG(mRen2)27 (Ren2) rats, with elevated serum aldosterone and proteinuria, and age-matched Sprague-Dawley rats were treated with either a low dose (1 mg/kg/day) or a conventional dose (30 mg/kg/day) of spironolactone (MR antagonist) or placebo for 3 weeks. RESULTS Ren2 rats displayed increases in urine levels of the PTC brush border lysosomal enzyme N-acetyl-β-aminoglycosidase (β-NAG) in conjunction with reductions in PTC megalin, the apical membrane adherens protein T-cadherin and basolateral α-(E)-catenin, and fibrosis. In concert with these abnormalities, Ren2 renal cortical tissue also displayed increased Ser2448 (p)/activation of mTOR and Thr389 (p)-S6K1 and increased 3-nitrotyrosine (3-NT) content, a marker for peroxynitrite. Low-dose spironolactone had no effect on blood pressure but decreased proteinuria and β-NAG comparable to a conventional dose of this MR antagonist. Both doses of spironolactone attenuated ultrastructural maladaptive alterations and led to comparable reductions in (p)-mTOR/(p)-S6K1, 3-NT, fibrosis, and increased expression of α-(E)-catenin, T- and N-cadherin. CONCLUSIONS Thereby, MR antagonism improves proximal tubule integrity by targeting mTOR/S6K1 signaling and redox status independent of changes in blood pressure.
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Conte D, Viscarra J, Nishiyama A, Ortiz RM. Chronic angiotensin receptor blockade suppresses intracardiac angiotensin II in angiotensin II-infused rats. Exp Biol Med (Maywood) 2011; 236:1449-53. [PMID: 22087022 DOI: 10.1258/ebm.2011.011159] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Accumulation of angiotensin II (Ang II) in tissues is an Ang II-receptor-mediated process. In pigs, acute angiotensin receptor blockade (ARB) reduced the heart-to-plasma ratio of Ang II following acute infusion. However in rats, chronic ARB treatment increased heart Ang II levels, suggesting that a differential response to ARB treatment may exist in the mammalian heart. Furthermore, the changes in heart aldosterone following chronic ARB treatment are not well described. To address the discrepancy in heart Ang II concentrations following ARB treatment, three groups (n = 6) of rats were chronically studied: (1) control; (2) angiotensin II (Ang II; 80 ng/min for 28 d); and (3) angiotensin II + olmesartan (ARB; 10 mg/kg/d for 21 d). Ang II-infusion increased intracardiac Ang II by 40% (53 ± 2 versus 74 ± 6 fmol/g) and intrarenal Ang II over 2-fold (96 ± 6 versus 207 ± 14 fmol/g), and chronic ARB treatment decreased Ang II by 48% in the heart (50 ± 7 fmol/g) and over two-fold in the kidney (92 ± 7 fmol/g), suggesting that accumulation of Ang II in the heart is receptor-mediated as in the kidney. Ang II increased plasma aldosterone 2.5-fold (1.4 ± 0.1 versus 3.5 ± 1.2 nmol/L) and was exacerbated by ARB treatment (5.6 ± 1.0 nmol/L). Intracardiac aldosterone was exacerbated by ARB treatment (control: 2.2 ± 0.3; Ang II: 2.7 ± 1.1; ARB: 7.8 ± 1.7 pmol/g). Suppression of intracardiac Ang II with ARB is consistent with the existing view of Ang II-receptor-mediated uptake by tissues.
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Affiliation(s)
- Debra Conte
- Division of Natural Sciences, University of California, Merced, CA 95343, USA
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Howard CG, Mitchell KD. Renal functional responses to selective intrarenal renin inhibition in Cyp1a1-Ren2 transgenic rats with ANG II-dependent malignant hypertension. Am J Physiol Renal Physiol 2011; 302:F52-9. [PMID: 21993885 DOI: 10.1152/ajprenal.00187.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Angiotensin (ANG) II-dependent hypertension is characterized by increases in intrarenal ANG II levels, derangement in renal hemodynamics, and augmented tubular sodium reabsorptive capability. Increased nephron expression of renin-angiotensin system components, such as angiotensinogen by proximal tubule cells and renin by collecting duct principal cells, has been associated with an augmented ability of the kidney to form ANG II in hypertensive states. However, the contribution of de novo intrarenal ANG II production to the development and maintenance of ANG II-dependent hypertension remains unclear. The present study was performed to determine the effects of selective intrarenal renin inhibition on whole kidney hemodynamics and renal excretory function in Cyp1a1-Ren2 rats with ANG II-dependent malignant hypertension in the absence of the confounding influence of associated reductions in mean arterial pressure (MAP). Male Cyp1a1-Ren2 transgenic rats were induced to develop malignant hypertension, anesthetized, and surgically prepared for intrarenal administration of the direct renin inhibitor aliskiren (0.01 mg/kg). Following acute aliskiren treatment, urine flow and sodium excretion increased (10.5 ± 1.1 to 15.9 ± 1.9 μl/min, P < 0.001; 550 ± 160 to 1,370 ± 320 neq/min, P < 0.001, respectively) and ANG II excretion decreased (120 ± 30 to 63 ± 17 fmol/h, P < 0.05). There were no significant changes in MAP, glomerular filtration rate, estimated renal plasma flow, plasma ANG II levels, or protein excretion. The present findings demonstrate that selective renal renin inhibition elicits diuretic and natriuretic responses in Cyp1a1-Ren2 rats with ANG II-dependent malignant hypertension. Elevated intraluminal ANG II levels likely act to augment tubular reabsorptive function and, thereby, contribute to the elevated blood pressure in Cyp1a1-Ren2 rats with ANG II-dependent malignant hypertension.
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Affiliation(s)
- Catherine G Howard
- Dept. of Physiology, Tulane Univ. Health Sciences Center, 1430 Tulane Ave., SL39, New Orleans, LA 70112, USA
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Graciano ML, Mitchell KD. Imatinib ameliorates renal morphological changes in Cyp1a1-Ren2 transgenic rats with inducible ANG II-dependent malignant hypertension. Am J Physiol Renal Physiol 2011; 302:F60-9. [PMID: 21975872 DOI: 10.1152/ajprenal.00218.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study was performed to assess the effects of the platelet-derived growth factor (PDGF) receptor kinase inhibitor imatinib mesylate on the renal morphological changes occurring during the development of malignant hypertension in transgenic rats with inducible expression of the Ren2 gene [TGR(Cyp1a1Ren2)]. Arterial blood pressure was measured by radiotelemetry in male Cyp1a1-Ren2 rats during control conditions and during dietary administration of indole-3-carbinol (I3C; 0.3%) for 14 days to induce malignant hypertension. Rats induced with I3C (n = 5) had higher mean arterial pressures (178 ± 4 vs. 109 ± 2 mmHg, P < 0.001) and increased urinary albumin excretion (Ualb; 13 ± 5 vs. 0.6 ± 0.2 mg/day) compared with noninduced rats (n = 5). Chronic administration of imatinib (60 mg·kg(-1)·day(-1) in drinking water, n = 5) did not alter the magnitude of the hypertension (176 ± 8 mmHg) but prevented the increase in Ualb (1.6 ± 0.3 mg/day). Quantitative analysis of proliferating cell nuclear antigen using immunohistochemistry demonstrated increased proliferating cell number in cortical tubules (38 ± 5 vs. 18 ± 1 cells/mm(2)) and cortical interstitium (40 ± 7 vs. 13 ± 6 cells/mm(2)) of hypertensive rat kidneys. Renal cortical fibrosis evaluated by picrosirius red staining showed increased collagen deposition in kidneys of the hypertensive rats (1.6 ± 0.1 vs. 0.4 ± 0.1% of cortical area). Imatinib attenuated the increase in proliferating cell number in cortical tubules and interstitium (22 ± 5 vs. 38 ± 5 and 22 ± 6 vs. 40 ± 7 cells/mm(2), respectively) and reduced the degree of collagen deposition (0.8 ± 0.2 vs. 1.6 ± 0.1%) in the kidneys of hypertensive rats. These findings demonstrate that the renal pathological changes that occur during the development of malignant hypertension in Cyp1a1-Ren2 rats involve activation of PDGF receptor kinase.
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Affiliation(s)
- Miguel L Graciano
- Dept. of Physiology, Tulane Univ. Health Sciences Center, 1430 Tulane Ave., SL39, New Orleans, LA 70112, USA
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Honetschlägerová Z, Husková Z, Vaňourková Z, Sporková A, Kramer HJ, Hwang SH, Tsai HJ, Hammock BD, Imig JD, Červenka L, Kopkan L. Renal mechanisms contributing to the antihypertensive action of soluble epoxide hydrolase inhibition in Ren-2 transgenic rats with inducible hypertension. J Physiol 2011; 589:207-19. [PMID: 21078594 PMCID: PMC3039270 DOI: 10.1113/jphysiol.2010.199505] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 11/09/2010] [Indexed: 01/01/2023] Open
Abstract
In the present study, we examined the effects of soluble epoxide hydrolase (sEH) inhibition on the development of angiotensin II-dependent hypertension and on renal function in transgenic rats with inducible expression of the mouse renin gene (strain name Cyp1a1-Ren-2). Hypertension was induced in these rats by indole-3-carbinol (I3C; 0.3% in the diet) for 12 days. The sEH inhibitor cis-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (c-AUCB) was given in two doses (13 or 26 mg l-1) in drinking water. Blood pressure (BP), body weight (BW) and renal excretory parameters were monitored in conscious animals during the experiment. Renal haemodynamics was assessed at the end of treatment in anaesthetized rats. I3C administration resulted in severe hypertension with a rise in systolic BP from 118 ± 2 to 202 ± 3 mmHg, a loss of BW from 266 ± 5 to 228 ± 4 g and a rise in proteinuria from 14 ± 2 to 34 ± 3 mg day-1. Both doses of c-AUCB significantly attenuated the development of hypertension (systolic BP of 181 ± 4 and 176 ± 4 mmHg, respectively), the loss in BW (256 ± 4 and 259 ± 3 g, respectively) and the degree of proteinuria (27 ± 2 and 25 ± 3 mg day-1, respectively) to a similar extent. Moreover, c-AUCB prevented the reduction in renal plasma flow (5.4 ± 0.4 vs. 4.6 ± 0.3 ml min-1 g-1) and significantly increased sodium excretion (0.84 ± 0.16 vs. 0.38 ± 0.08 μmol min-1 g-1) during I3C administration. These data suggest that the oral administration of c-AUCB displays antihypertensive effects in Ren-2 transgenic rats with inducible malignant hypertension via an improvement of renal function.
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Affiliation(s)
- Zuzana Honetschlägerová
- Department of Experimental Medicine, Institute for Clinical and Experimental Medicine, Prague, Czech Republic
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Enhanced urinary angiotensinogen excretion in Cyp1a1-Ren2 transgenic rats with inducible ANG II-dependent malignant hypertension. Am J Med Sci 2010; 340:389-94. [PMID: 20724906 DOI: 10.1097/maj.0b013e3181eabd28] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
INTRODUCTION Previous studies have demonstrated that the urinary excretion of angiotensinogen is significantly increased in ANG II-infused hypertensive rats, which is associated with an augmentation of intrarenal ANG II levels. These findings suggest that urinary angiotensinogen excretion rates provide an index of intrarenal ANG II levels in ANG II-dependent hypertensive states. However, little information is available regarding the urinary excretion of angiotensinogen in ANG II-dependent malignant hypertension. METHODS This study was performed to determine if urinary angiotensinogen excretion is increased in Cyp1a1-Ren2 transgenic rats [strain name: TGR(Cyp1aRen2)] with inducible ANG II-dependent malignant hypertension. Adult male Cyp1a1-Ren2 rats (n = 6) were fed a normal diet containing 0.3% indole-3-carbinol (I3C) for 10 days to induce ANG II-dependent malignant hypertension. RESULTS Rats induced with I3C exhibited pronounced increases in systolic blood pressure (208 ± 7 versus 127 ± 3 mm Hg; P < 0.001), marked proteinuria (29.4 ± 3.6 versus 5.9 ± 0.3 mg/d; P < 0.001) and augmented urinary angiotensinogen excretion (996 ± 186 versus 241 ± 31 ng/d; P < 0.01). Chronic administration of the AT₁ receptor antagonist, candesartan (25 mg/L in drinking water, n = 6), prevented the I3C-induced increases in systolic blood pressure (125 ± 5 mm Hg; P < 0.001), proteinuria (7.3 ± 1.0 mg/d; P < 0.001) and urinary angiotensinogen excretion (488 ± 51 ng/d, P < 0.01). CONCLUSIONS These data demonstrate that the urinary excretion of angiotensinogen is markedly augmented in ANG II-dependent malignant hypertension. Such increased urinary angiotensinogen excretion may contribute to augmented intrarenal ANG II levels and, thereby, to the increased blood pressure in Cyp1a1-Ren2 transgenic rats with inducible ANG II-dependent malignant hypertension.
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Prieto MC, Williams DE, Liu L, Kavanagh KL, Mullins JJ, Mitchell KD. Enhancement of renin and prorenin receptor in collecting duct of Cyp1a1-Ren2 rats may contribute to development and progression of malignant hypertension. Am J Physiol Renal Physiol 2010; 300:F581-8. [PMID: 21068087 DOI: 10.1152/ajprenal.00433.2010] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
To determine whether in the transgenic rat model [TGR(Cyp1a1Ren2)] with inducible ANG II-dependent malignant hypertension changes in the activation of intrarenal renin-angiotensin system may contribute to the pathogenesis of hypertension, we examined the gene expression of angiotensinogen (AGT) in renal cortical tissues and renin and prorenin receptor [(P)RR] in the collecting duct (CD) of the kidneys from Cyp1a1Ren2 rats (n = 6) fed a normal diet containing 0.3% indole-3-carbinol (I3C) for 10 days and noninduced rats maintained on a normal diet (0.6% NaCl diet; n = 6). Rats induced with I3C developed malignant hypertension and exhibited alterations in the expression of renin and (P)RR expressed by the CD cells. In the renal medullary tissues of the Cyp1a1Ren2 transgenic rats with malignant hypertension, renin protein levels in CD cells were associated with maintained renin content and lack of suppression of the endogenous Ren1c gene expression. Furthermore, these tissues exhibited increased levels of (P)RR transcript, as well as of the protein levels of the soluble form of this receptor, the s(P)RR. Intriguingly, although previous findings demonstrated that urinary AGT excretion is augmented in Cyp1a1Ren2 transgenic rats with malignant hypertension, in the present study we did not find changes in the gene expression of AGT in renal cortical tissues of these rats. The data suggest that upregulation of renin and the s(P)RR in the CD, especially in the renal medullary tissues of Cyp1a1Ren2 transgenic rats with malignant hypertension, along with the previously demonstrated increased availability of AGT in the urine of these rats, may constitute a leading mechanism to explain elevated formation of kidney ANG II levels in this model of ANG II-dependent hypertension.
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Affiliation(s)
- Minolfa C Prieto
- Department of Physiology, Tulane University, School of Medicine, New Orleans, LA 70112, USA.
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22
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Amiloride lowers arterial pressure in cyp1a1ren-2 transgenic rats without affecting renal vascular function. J Hypertens 2010; 28:2267-77. [DOI: 10.1097/hjh.0b013e32833d77b4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Ortiz RM, Kobori H, Conte D, Navar LG. Angiotensin II-induced reduction in body mass is Ang II receptor mediated in association with elevated corticosterone. Growth Horm IGF Res 2010; 20:282-288. [PMID: 20483644 PMCID: PMC2918720 DOI: 10.1016/j.ghir.2010.03.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 03/15/2010] [Accepted: 03/22/2010] [Indexed: 12/27/2022]
Abstract
The mechanisms by which elevated glucocorticoids contribute to decreased body mass via angiotensin II (Ang II) infusion are not completely described. This study addressed the hypothesis that chronic Ang II infusion suppresses hepatic growth hormone receptor (GHr) and IGF1 expressions via an Ang II receptor (AT1)-mediated pathway associated with elevated glucocorticoids. Sprague-Dawley rats were assigned to three groups: 1) Control, 2) Ang II-infused (80 ng/min x 28d) and 3) Ang II+angiotensin receptor blocker (ARB; 10 mg losartan/kg/d x 21d). After 28d, Ang II decreased body mass by 14% (407+/-8 vs 350+/-17 g) and hepatic AT1a, GHr, and IGF1 mRNA expressions by 45%, 44%, and 44%, respectively. ARB treatment completely prevented the loss in body mass (409+/-9 g) and AT1a and GHr expressions and partially recovered the loss of hepatic IGF1. Ang II increased plasma corticosterone (B) 3-fold (173+/-28 vs 555+/-42 ng/mL) and ARB treatment prevented the response (150+/-47 ng/mL). Food consumption did not change suggesting that the decrease in body mass resulted from the catabolic actions of the Ang II-induced increase in systemic B and not from reduced caloric intake. The prevention by ARB treatment of the Ang II-induced decrease in body mass and downregulation of AT1a, GHr and IGF1 coinciding with suppression of plasma B suggests that the Ang II-induced decrease in body mass is AT1 receptor mediated in conjunction with elevated B. These data suggest that alleviating the Ang II-induced cachexia requires targeting AT1 and suppressing glucocorticoid secretion.
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Affiliation(s)
- Rudy M Ortiz
- School of Natural Sciences, University of California, Merced 95344, USA.
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Transient induction of ANG II-dependent malignant hypertension causes sustained elevation of blood pressure and augmentation of the pressor response to ANG II in CYP1A1-REN2 transgenic rats. Am J Med Sci 2010; 339:543-8. [PMID: 20375689 DOI: 10.1097/maj.0b013e3181d82a62] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Transgenic rats with inducible expression of the mouse Ren2 renin gene [strain name: TGR(Cyp1a1Ren2)] allow induction of various degrees of ANG II-dependent hypertension. Dietary administration of the aryl hydrocarbon indole-3-carbinol (I3C) at a dose of 0.15% induces a slowly developing form of ANG II-dependent hypertension, whereas dietary administration of a higher dose (0.3%) of I3C results in the development of ANG II-dependent malignant hypertension. Cessation of administration of 0.15% I3C results in the normalization of blood pressure, indicating the reversibility of hypertension induced by this dose of I3C. The present study was performed to determine if ANG II-dependent malignant hypertension is similarly reversible following cessation of dietary administration of 0.3% I3C. METHODS Cyp1a1-Ren2 rats (n = 6) were fed a normal diet containing 0.3% I3C for 11 days to induce malignant hypertension. RESULTS Cyp1a1-Ren2 rats induced with I3C exhibited pronounced increases in systolic blood pressure (SBP) (132 +/- 3-229 +/- 11 mm Hg, P < 0.001) and marked decreases in body weight (303 +/- 4-222 +/- 2 g, P < 0.001). When I3C administration was terminated, SBP decreased to 167 +/- 4 mm Hg (P < 0.01) and body weight increased to normal levels (309 +/- 2 g, P < 0.01) within 12 days. However, SBP remained significantly elevated (172 +/- 1 mm Hg, P < 0.01) for up to 3 weeks after termination of dietary administration of 0.3% I3C. In addition, the magnitude of the blood pressure response to intravenous bolus administration of 50 ng of ANG II (50 microL in volume) 3 weeks after cessation of dietary I3C administration was substantially higher than that observed in normotensive control rats (134 +/- 1 mm Hg, n = 6) not previously induced with 0.3% I3C (53 +/- 2 versus 38 +/- 3 mm Hg, P < 0.05). CONCLUSIONS The present findings demonstrate that transient induction of ANG II-dependent malignant hypertension results in prolonged elevations of arterial blood pressure and marked augmentation of the magnitude of the pressor response to ANG II in Cyp1a1-Ren2 transgenic rats.
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Yeyati NL, Altuna ME, Damasco MC, Mac Laughlin MA. Role of 11beta-hydroxysteroid dehydrogenase 2 renal activity in potassium homeostasis in rats with chronic renal failure. Braz J Med Biol Res 2009; 43:52-6. [PMID: 20027486 DOI: 10.1590/s0100-879x2009007500028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2008] [Accepted: 11/26/2009] [Indexed: 11/22/2022] Open
Abstract
Aldosterone concentrations vary in advanced chronic renal failure (CRF). The isozyme 11beta-hydroxysteroid dehydrogenase 2 (11beta-HSD2), which confers aldosterone specificity for mineralocorticoid receptors in distal tubules and collecting ducts, has been reported to be decreased or normal in patients with renal diseases. Our objective was to determine the role of aldosterone and 11beta-HSD2 renal microsome activity, normalized for glomerular filtration rate (GFR), in maintaining K+ homeostasis in 5/6 nephrectomized rats. Male Wistar rats weighing 180-220 g at the beginning of the study were used. Rats with experimental CRF obtained by 5/6 nephrectomy (N = 9) and sham rats (N = 10) were maintained for 4 months. Systolic blood pressure and plasma creatinine (Pcr) concentration were measured at the end of the experiment. Sodium and potassium excretion and GFR were evaluated before and after spironolactone administration (10 mg.kg-1.day-1 for 7 days) and 11beta-HSD2 activity on renal microsomes was determined. Systolic blood pressure (means +/- SEM; Sham = 105 +/- 8 and CRF = 149 +/- 10 mmHg) and Pcr (Sham = 0.42 +/- 0.03 and CRF = 2.53 +/- 0.26 mg/dL) were higher (P < 0.05) while GFR (Sham = 1.46 +/- 0.26 and CRF = 0.61 +/- 0.06 mL/min) was lower (P < 0.05) in CRF, and plasma aldosterone (Pald) was the same in the two groups. Urinary sodium and potassium excretion was similar in the two groups under basal conditions but, after spironolactone treatment, only potassium excretion was decreased in CRF rats (sham = 0.95 +/- 0.090 (before) vs 0.89 +/- 0.09 microEq/min (after) and CRF = 1.05 +/- 0.05 (before) vs 0.37 +/- 0.07 microEq/min (after); P < 0.05). 11beta-HSD2 activity on renal microsomes was lower in CRF rats (sham = 0.807 +/- 0.09 and CRF = 0.217 +/- 0.07 nmol.min-1.mg protein-1; P < 0.05), although when normalized for mL GFR it was similar in both groups. We conclude that K+ homeostasis is maintained during CRF development despite normal Pald levels. This adaptation may be mediated by renal 11beta-HSD2 activity, which, when normalized for GFR, became similar to that of control rats, suggesting that mineralocorticoid receptors maintain their aldosterone selectivity.
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Affiliation(s)
- N L Yeyati
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
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Liu X, Bellamy COC, Bailey MA, Mullins LJ, Dunbar DR, Kenyon CJ, Brooker G, Kantachuvesiri S, Maratou K, Ashek A, Clark AF, Fleming S, Mullins JJ. Angiotensin-converting enzyme is a modifier of hypertensive end organ damage. J Biol Chem 2009; 284:15564-72. [PMID: 19307186 PMCID: PMC2708853 DOI: 10.1074/jbc.m806584200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Revised: 03/06/2009] [Indexed: 11/06/2022] Open
Abstract
Severe forms of hypertension are characterized by high blood pressure combined with end organ damage. Through the development and refinement of a transgenic rat model of malignant hypertension incorporating the mouse renin gene, we previously identified a quantitative trait locus on chromosome 10, which affects malignant hypertension severity and morbidity. We next generated an inducible malignant hypertensive model where the timing, severity, and duration of hypertension was placed under the control of the researcher, allowing development of and recovery from end organ damage to be investigated. We have now generated novel consomic Lewis and Fischer rat strains with inducible hypertension and additional strains that are reciprocally congenic for the refined chromosome 10 quantitative trait locus. We have captured a modifier of end organ damage within the congenic region and, using a range of bioinformatic, biochemical and molecular biological techniques, have identified angiotensin-converting enzyme as the modifier of hypertension-induced tissue microvascular injury. Reciprocal differences between angiotensin-converting enzyme and the anti-inflammatory tetrapeptide, N-acetyl-Ser-Asp-Lys-Pro in the kidney, a tissue susceptible to end organ damage, suggest a mechanism for the amelioration of hypertension-dependent damage.
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Affiliation(s)
- Xiaojun Liu
- From the Molecular Physiology Laboratory, Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom
| | | | - Matthew A. Bailey
- From the Molecular Physiology Laboratory, Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom
| | - Linda J. Mullins
- From the Molecular Physiology Laboratory, Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom
| | - Donald R. Dunbar
- From the Molecular Physiology Laboratory, Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom
| | - Christopher J. Kenyon
- From the Molecular Physiology Laboratory, Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom
| | - Gillian Brooker
- From the Molecular Physiology Laboratory, Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom
| | | | - Klio Maratou
- the Medical Research Council Clinical Sciences Centre, Hammersmith Hospital, London W12 ONN, United Kingdom, and
| | - Ali Ashek
- From the Molecular Physiology Laboratory, Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom
| | - Allan F. Clark
- From the Molecular Physiology Laboratory, Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom
| | | | - John J. Mullins
- From the Molecular Physiology Laboratory, Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom
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Ortiz RM. Delineating the contributions of AT1a and AT1b receptor-mediated uptake of ANG II in kidneys and adrenals. Am J Physiol Renal Physiol 2008; 294:F291-2. [DOI: 10.1152/ajprenal.00589.2007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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