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Ramachandran CD, Gholami K, Lam SK, Hoe SZ. A preliminary study of the effect of a high-salt diet on transcriptome dynamics in rat hypothalamic forebrain and brainstem cardiovascular control centers. PeerJ 2020; 8:e8528. [PMID: 32175184 PMCID: PMC7059759 DOI: 10.7717/peerj.8528] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 01/07/2020] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND High dietary salt intake is strongly correlated with cardiovascular (CV) diseases and it is regarded as a major risk factor associated with the pathogenesis of hypertension. The CV control centres in the brainstem (the nucleus tractus solitarii (NTS) and the rostral ventrolateral medulla (RVLM)) and hypothalamic forebrain (the subfornical organ, SFO; the supraoptic nucleus, SON and the paraventricular nucleus, PVN) have critical roles in regulating CV autonomic motor outflows, and thus maintaining blood pressure (BP). Growing evidence has implicated autonomic regulatory networks in salt-sensitive HPN (SSH), but the genetic basis remains to be delineated. We hypothesized that the development and/ or maintenance of SSH is reliant on the change in the expression of genes in brain regions controlling the CV system. METHODOLOGY We used RNA-Sequencing (RNA-Seq) to describe the differential expression of genes in SFO, SON, PVN, NTS and RVLM of rats being chronically fed with high-salt (HS) diet. Subsequently, a selection of putatively regulated genes was validated with quantitative reverse transcription polymerase chain reaction (qRT-PCR) in both Spontaneously Hypertensive rats (SHRs) and Wistar Kyoto (WKY) rats. RESULTS The findings enabled us to identify number of differentially expressed genes in SFO, SON, PVN, NTS and RVLM; that are either up-regulated in both strains of rats (SON- Caprin2, Sctr), down-regulated in both strains of rats (PVN- Orc, Gkap1), up-regulated only in SHRs (SFO- Apopt1, Lin52, AVP, OXT; SON- AVP, OXT; PVN- Caprin2, Sclt; RVLM- A4galt, Slc29a4, Cmc1) or down-regulated only in SHRs (SON- Ndufaf2, Kcnv1; PVN- Pi4k2a; NTS- Snrpd2l, Ankrd29, St6galnac6, Rnf157, Iglon5, Csrnp3, Rprd1a; RVLM- Ttr, Faim). CONCLUSIONS These findings demonstrated the adverse effects of HS diet on BP, which may be mediated via modulating the signaling systems in CV centers in the hypothalamic forebrain and brainstem.
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Affiliation(s)
- Chitra Devi Ramachandran
- Department of Physiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Wilayah Perseketuan, Malaysia
| | - Khadijeh Gholami
- Department of Physiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Wilayah Perseketuan, Malaysia
- Human Biology Division, School of Medicine, International Medical University, Kuala Lumpur, Wilayah Perseketuan, Malaysia
| | - Sau Kuen Lam
- Department of Physiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Wilayah Perseketuan, Malaysia
- Department of Pre-Clinical Sciences, Faculty of Medicine and Health Sciences, Universiti Tunku Abdul Rahman, Sungai Long, Selangor, Malaysia
| | - See Ziau Hoe
- Department of Physiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Wilayah Perseketuan, Malaysia
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Carvalho-Galvão A, Guimarães DD, De Brito Alves JL, Braga VA. Central Inhibition of Tumor Necrosis Factor Alpha Reduces Hypertension by Attenuating Oxidative Stress in the Rostral Ventrolateral Medulla in Renovascular Hypertensive Rats. Front Physiol 2019; 10:491. [PMID: 31114507 PMCID: PMC6502978 DOI: 10.3389/fphys.2019.00491] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 04/08/2019] [Indexed: 12/14/2022] Open
Abstract
Inflammation in the central nervous system is being considered a key player linked to neurogenic hypertension. Using combined in vivo and in vitro approaches, we investigated the effects of central inhibition of TNF-α on blood pressure, sympathetic tone, baroreflex sensitivity, and oxidative stress in the rostral ventrolateral medulla (RVLM) of rats with 2-kidney-1-clip (2K1C) renovascular hypertension. Continuous infusion of pentoxifylline, a TNF-α inhibitor, into the lateral ventricle of the brain for 14 consecutive days reduced blood pressure and improved baroreflex sensitivity in renovascular hypertensive rats. Furthermore, central TNF-α inhibition reduced sympathetic modulation and blunted the increased superoxide accumulation in the RVLM of 2K1C rats. Our findings suggest that TNF-α play an important role in the maintenance of sympathetic vasomotor tone and increased oxidative stress in the RVLM during renovascular hypertension.
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Affiliation(s)
| | - Drielle D Guimarães
- Biotechnology Center, Federal University of Paraíba, João Pessoa, Brazil.,Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - José L De Brito Alves
- Department of Nutrition, Health Sciences Center, Federal University of Paraíba, João Pessoa, Brazil
| | - Valdir A Braga
- Biotechnology Center, Federal University of Paraíba, João Pessoa, Brazil.,Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
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3
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Guimarães DD, Cruz JC, Carvalho-Galvão A, Zhuge Z, Marques SM, Naves LM, Persson AEG, Weitzberg E, Lundberg JO, Balarini CM, Pedrino GR, Braga VA, Carlström M. Dietary Nitrate Reduces Blood Pressure in Rats With Angiotensin II–Induced Hypertension via Mechanisms That Involve Reduction of Sympathetic Hyperactivity. Hypertension 2019; 73:839-848. [DOI: 10.1161/hypertensionaha.118.12425] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Drielle D. Guimarães
- From the Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (D.D.G., J.C.C., Z.Z., A.E.G.P., E.W., J.O.L., M.C.)
- Biotechnology Center (D.D.G., J.C.C., A.C.-G., C.M.B., V.A.B.), Federal University of Paraiba, Joao Pessoa, Brazil
| | - Josiane C. Cruz
- From the Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (D.D.G., J.C.C., Z.Z., A.E.G.P., E.W., J.O.L., M.C.)
- Biotechnology Center (D.D.G., J.C.C., A.C.-G., C.M.B., V.A.B.), Federal University of Paraiba, Joao Pessoa, Brazil
| | - Alynne Carvalho-Galvão
- Biotechnology Center (D.D.G., J.C.C., A.C.-G., C.M.B., V.A.B.), Federal University of Paraiba, Joao Pessoa, Brazil
| | - Zhengbing Zhuge
- From the Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (D.D.G., J.C.C., Z.Z., A.E.G.P., E.W., J.O.L., M.C.)
| | - Stefanne M. Marques
- Department of Physiological Sciences, Federal University of Goias, Goiania, Brazil (S.M.M., L.M.N., G.R.P.)
| | - Lara M. Naves
- Department of Physiological Sciences, Federal University of Goias, Goiania, Brazil (S.M.M., L.M.N., G.R.P.)
| | - A. Erik G. Persson
- From the Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (D.D.G., J.C.C., Z.Z., A.E.G.P., E.W., J.O.L., M.C.)
- Department of Medical Cell Biology, Uppsala University, Sweden (A.E.G.P.)
| | - Eddie Weitzberg
- From the Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (D.D.G., J.C.C., Z.Z., A.E.G.P., E.W., J.O.L., M.C.)
| | - Jon O. Lundberg
- From the Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (D.D.G., J.C.C., Z.Z., A.E.G.P., E.W., J.O.L., M.C.)
| | - Camille M. Balarini
- Biotechnology Center (D.D.G., J.C.C., A.C.-G., C.M.B., V.A.B.), Federal University of Paraiba, Joao Pessoa, Brazil
- Health Sciences Center (C.M.B.), Federal University of Paraiba, Joao Pessoa, Brazil
| | - Gustavo R. Pedrino
- Department of Physiological Sciences, Federal University of Goias, Goiania, Brazil (S.M.M., L.M.N., G.R.P.)
| | - Valdir A. Braga
- Biotechnology Center (D.D.G., J.C.C., A.C.-G., C.M.B., V.A.B.), Federal University of Paraiba, Joao Pessoa, Brazil
| | - Mattias Carlström
- From the Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (D.D.G., J.C.C., Z.Z., A.E.G.P., E.W., J.O.L., M.C.)
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4
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Hypothalamic Inflammation at a Crossroad of Somatic Diseases. Cell Mol Neurobiol 2018; 39:11-29. [DOI: 10.1007/s10571-018-0631-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 10/24/2018] [Indexed: 02/08/2023]
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5
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Nogueira V, Brito-Alves J, Fontes D, Oliveira L, Lucca W, Tourneur Y, Wanderley A, da Silva GSF, Leandro C, Costa-Silva JH. Carotid body removal normalizes arterial blood pressure and respiratory frequency in offspring of protein-restricted mothers. Hypertens Res 2018; 41:1000-1012. [PMID: 30242293 DOI: 10.1038/s41440-018-0104-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 03/12/2018] [Accepted: 03/26/2018] [Indexed: 12/25/2022]
Abstract
The aim of this study is to evaluate the short-term and long-term effects elicited by carotid body removal (CBR) on ventilatory function and the development of hypertension in the offspring of malnourished rats. Wistar rats were fed a normo-protein (NP, 17% casein) or low-protein (LP, 8% casein) diet during pregnancy and lactation. At 29 days of age, the animals were submitted to CBR or a sham surgery, according to the following groups: NP-cbr, LP-cbr, NP-sham, or LP-sham. In the short-term, at 30 days of age, the respiratory frequency (RF) and immunoreactivity for Fos on the retrotrapezoid nucleus (RTN; brainstem site containing CO2 sensitive neurons) after exposure to CO2 were evaluated. In the long term, at 90 days of age, arterial pressure (AP), heart rate (HR), and cardiovascular variability were evaluated. In the short term, an increase in the baseline RF (~6%), response to CO2 (~8%), and Fos in the RTN (~27%) occurred in the LP-sham group compared with the NP-sham group. Interestingly, the CBR in the LP group normalized the RF in response to CO2 as well as RTN cell activation. In the long term, CBR reduced the mean AP by ~20 mmHg in malnourished rats. The normalization of the arterial pressure was associated with a decrease in the low-frequency (LF) oscillatory component of AP (~58%) and in the sympathetic tonus to the cardiovascular system (~29%). In conclusion, carotid body inputs in malnourished offspring may be responsible for the following: (i) enhanced respiratory frequency and CO2 chemosensitivity in early life and (ii) the production of autonomic imbalance and the development of hypertension.
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Affiliation(s)
- Viviane Nogueira
- Department of Physical Education and Sports Sciences, Federal University of Pernambuco, Vitória de Santo Antão, PE, Brazil
| | - Jose Brito-Alves
- Department of Physical Education and Sports Sciences, Federal University of Pernambuco, Vitória de Santo Antão, PE, Brazil
| | - Danilo Fontes
- Department of Physical Education and Sports Sciences, Federal University of Pernambuco, Vitória de Santo Antão, PE, Brazil
| | - Larissa Oliveira
- Department of Morphology, Federal University of Sergipe, Aracajú, SE, Brazil
| | - Waldecy Lucca
- Department of Morphology, Federal University of Sergipe, Aracajú, SE, Brazil
| | - Yves Tourneur
- Department of Physical Education and Sports Sciences, Federal University of Pernambuco, Vitória de Santo Antão, PE, Brazil.,Centre National de la Recherche Scientifique, Université Claude Bernard, Lyon 1, Lyon, France
| | - Almir Wanderley
- Department of Physiology and Pharmacology, Federal University of Pernambuco, Recife, PE, Brazil
| | - Glauber S F da Silva
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Carol Leandro
- Department of Physical Education and Sports Sciences, Federal University of Pernambuco, Vitória de Santo Antão, PE, Brazil
| | - João Henrique Costa-Silva
- Department of Physical Education and Sports Sciences, Federal University of Pernambuco, Vitória de Santo Antão, PE, Brazil.
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Schreier B, Hünerberg M, Mildenberger S, Rabe S, Bethmann D, Wickenhauser C, Gekle M. Deletion of the EGF receptor in vascular smooth muscle cells prevents chronic angiotensin II-induced arterial wall stiffening and media thickening. Acta Physiol (Oxf) 2018; 222. [PMID: 29152859 DOI: 10.1111/apha.12996] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 11/09/2017] [Accepted: 11/10/2017] [Indexed: 01/13/2023]
Abstract
AIM In vivo vascular smooth muscle cell (VSMC) EGF receptor (EGFR) contributes to acute angiotensin II (AII) effects on vascular tone and blood pressure. The ubiquitously expressed EGFR has been implicated in vascular remodelling preceding end-organ damage by pharmacological inhibition, and AII signalling in cultured vascular cells is partly EGFR-dependent. However, the role of VSMC-EGFR in vivo during AII-induced pathophysiological processes is not known. METHODS This study assesses the in vivo relevance of VSMC-EGFR during chronic AII challenge without further stressors, using a mouse model with inducible, VSMC-specific EGFR knock out (VSMC-EGFR-KO). In these mice functional and structural vascular, renal and cardiac effects or biomarkers were investigated in vivo and ex vivo. RESULTS Vascular smooth muscle cell-EGFR-KO prevented AII-induced media hypertrophy of mesenteric arteries, renal arterioles and the aorta, VSMC ERK1/2-phosphorylation as well as the impairment of vascular compliance. Furthermore, induction of vascular fibrosis, creatinineamia, renal interstitial fibrosis as well as the increase in fractional water excretion was prevented. AII-induced increase in systolic blood pressure was mitigated. By contrast, endothelial dysfunction, induction of vascular inflammatory marker mRNA and albuminuria were not inhibited. Cardiac and cardiomyocyte hypertrophy were also not prevented by VSMC-EGFR-KO. CONCLUSION Vascular smooth muscle cell-EGFRs are relevant for pathological AII action in vivo. Our data show in vivo and ex vivo the necessity of VSMC-EGFR for AII-induced structural and functional vascular remodelling, not including endothelial dysfunction. Hereby, VSMC-EGFR gains importance for complete AII-induced renal end-organ damage succeeding vascular remodelling.
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Affiliation(s)
- B. Schreier
- Julius-Bernstein-Institute of Physiology; Martin Luther University Halle-Wittenberg; Halle Germany
| | - M. Hünerberg
- Julius-Bernstein-Institute of Physiology; Martin Luther University Halle-Wittenberg; Halle Germany
| | - S. Mildenberger
- Julius-Bernstein-Institute of Physiology; Martin Luther University Halle-Wittenberg; Halle Germany
| | - S. Rabe
- Julius-Bernstein-Institute of Physiology; Martin Luther University Halle-Wittenberg; Halle Germany
| | - D. Bethmann
- Institute of Pathology; Martin Luther University Halle-Wittenberg; Halle Germany
| | - C. Wickenhauser
- Institute of Pathology; Martin Luther University Halle-Wittenberg; Halle Germany
| | - M. Gekle
- Julius-Bernstein-Institute of Physiology; Martin Luther University Halle-Wittenberg; Halle Germany
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7
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Figueiredo EAD, Alves NFB, Monteiro MMDO, Cavalcanti CDO, Silva TMSD, Silva TMGD, Braga VDA, Oliveira EDJ. Antioxidant and Antihypertensive Effects of a Chemically Defined Fraction of Syrah Red Wine on Spontaneously Hypertensive Rats. Nutrients 2017; 9:nu9060574. [PMID: 28587200 PMCID: PMC5490553 DOI: 10.3390/nu9060574] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 03/06/2017] [Accepted: 03/07/2017] [Indexed: 12/11/2022] Open
Abstract
A particularly phenolic-rich fraction extracted from red wine from the São Francisco valley (Northeastern Brazil) was chemically characterized and its hypotensive and antioxidant effects on spontaneously hypertensive rats were studied both in vitro and in vivo. The liquid-liquid pH dependent fractionation scheme afforded a fraction with high content of bioactive phenolics such as flavonols, flavonol glycosides, phenolic acids and anthocyanins, whose identities were confirmed by liquid chromatography coupled to mass spectrometry analysis. Pretreatment of spontaneously hypertensive rats with this wine fraction at doses of 50 and 100 mg/kg by gavage for 15 days was able to decrease mean arterial pressure and heart rate as well as decrease serum lipid peroxidation. The fraction at concentrations of 0.01–1000 µg/mL induced concentration-dependent relaxation of isolated rat superior mesenteric artery rings pre-contracted with phenylephrine and this effect was not attenuated by endothelium removal. Our results demonstrate it is possible for phenolic constituents of red wine that are orally bioavailable to exert in vivo hypotensive and antioxidant effects on intact endothelial function.
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Affiliation(s)
- Eugênia Abrantes de Figueiredo
- Centro de Biotecnologia, Programa de Pós Graduação em Produtos Naturais e Sintéticos Bioativos, Campus I, João Pessoa, PB 58051-970, Brazil.
| | - Naiane Ferraz Bandeira Alves
- Centro de Biotecnologia, Programa de Pós Graduação em Produtos Naturais e Sintéticos Bioativos, Campus I, João Pessoa, PB 58051-970, Brazil.
| | - Matheus Morais de Oliveira Monteiro
- Centro de Biotecnologia, Programa de Pós Graduação em Produtos Naturais e Sintéticos Bioativos, Campus I, João Pessoa, PB 58051-970, Brazil.
| | - Clenia de Oliveira Cavalcanti
- Centro de Biotecnologia, Programa de Pós Graduação em Produtos Naturais e Sintéticos Bioativos, Campus I, João Pessoa, PB 58051-970, Brazil.
| | - Tania Maria Sarmento da Silva
- Departamento de Química, Laboratório de Bioprospecção Fitoquímica, Universidade Federal Rural de Pernambuco, Recife, PE 52171-900, Brazil.
| | - Telma Maria Guedes da Silva
- Departamento de Química, Laboratório de Bioprospecção Fitoquímica, Universidade Federal Rural de Pernambuco, Recife, PE 52171-900, Brazil.
| | - Valdir de Andrade Braga
- Centro de Biotecnologia, Programa de Pós Graduação em Produtos Naturais e Sintéticos Bioativos, Campus I, João Pessoa, PB 58051-970, Brazil.
| | - Eduardo de Jesus Oliveira
- Departamento de Farmácia, Universidade Federal dos Vales do Jequitinhonha e Mucurí, Diamantina, MG, 39100-000, Brazil.
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Subramanian M, MohanKumar SMJ, Balasubramanian P, Northcott CA, Garver H, Fink GD, MohanKumar PS. Chronic exposure to low doses of estradiol-17ß increases blood pressure in young female rats: A possible role for central Endothelin-1. Sci Rep 2017; 7:139. [PMID: 28273940 PMCID: PMC5428019 DOI: 10.1038/s41598-017-00213-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 02/14/2017] [Indexed: 02/04/2023] Open
Abstract
Previously, we demonstrated that chronic exposure to low levels of estradiol-17β (E2) increases mean arterial pressure (MAP) in young female Sprague-Dawley (SD) rats, however, the underlying mechanisms are unclear. Since endothelin-1 (ET-1) is implicated in blood pressure (BP) regulation, we hypothesized that E2’s effects on MAP are mediated through central ET-1. To test this, young female SD rats were either sham implanted or implanted s.c. with slow-release E2 pellets (20 ng/day for 90 days). BP was monitored by telemetry. After 75 days of E2 exposure, ETA antagonist or vehicle was administered i.c.v. After 90 days of E2 exposure, rats were sacrificed, and the paraventricular nucleus (PVN) and rostral ventrolateral medulla (RVLM) were microdissected for gene expression and protein analysis of ET-1 and its receptors. E2 exposure increased MAP after pellet implantation. Gene expression of ET-1 and ETA but not ETB receptors were upregulated in the PVN and RVLM of E2 treated animals. Further, the protein levels of ETA receptor were also increased in the PVN of E2 treated animals. However, i.c.v. infusion of the ETA antagonist did not completely block the increase in blood pressure. Our results suggest that increases in central ET-1 activity could possibly play a role in chronic E2-induced increase in BP but further studies are needed to completely understand the contribution of ET-1 in this phenomenon.
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Affiliation(s)
- Madhan Subramanian
- Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI, 48824, USA
| | - Sheba M J MohanKumar
- Department of Veterinary Biosciences and Diagnostic Imaging, University of Georgia, Athens, GA, 30602, USA.,Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, 48824, USA
| | - Priya Balasubramanian
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, 48824, USA
| | - Carrie A Northcott
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, 48824, USA
| | - Hannah Garver
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, 48824, USA
| | - Gregory D Fink
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, 48824, USA
| | - P S MohanKumar
- Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI, 48824, USA. .,Department of Veterinary Biosciences and Diagnostic Imaging, University of Georgia, Athens, GA, 30602, USA.
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Alves NFB, de Queiroz TM, de Almeida Travassos R, Magnani M, de Andrade Braga V. Acute Treatment with Lauric Acid Reduces Blood Pressure and Oxidative Stress in Spontaneously Hypertensive Rats. Basic Clin Pharmacol Toxicol 2017; 120:348-353. [DOI: 10.1111/bcpt.12700] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 11/02/2016] [Indexed: 02/02/2023]
Affiliation(s)
| | | | | | - Marciane Magnani
- Technology Center; Federal University of Paraíba; João Pessoa PB Brazil
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10
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Shimoura CG, Lincevicius GS, Nishi EE, Girardi ACC, Simon KA, Bergamaschi CT, Campos RR. Increased Dietary Salt Changes Baroreceptor Sensitivity and Intrarenal Renin-Angiotensin System in Goldblatt Hypertension. Am J Hypertens 2017; 30:28-36. [PMID: 27629265 DOI: 10.1093/ajh/hpw107] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 08/18/2016] [Accepted: 08/19/2016] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Renovascular hypertension (2-kidney 1-clip model (2K1C)) is characterized by renin-angiotensin system (RAS) activation. Increased Angiotensin II (AngII) leads to sympathoexcitation, oxidative stress, and alterations in sodium and water balance. AIM The aim of this study was to evaluate whether a discrete increase in sodium chloride intake in 2K1C rats leads to changes in cardiovascular and autonomic function, oxidative stress, and renin angiotensin aldosterone system. METHODS After 4 weeks of induction of hypertension, rats were fed a normal sodium diet (0.4% NaCl) or a high-sodium diet (2% NaCl) for 2 consecutive weeks. Experiments were carried out for 6 weeks after clipping. Mean arterial pressure (MAP), renal sympathetic nerve activity (rSNA), arterial baroreflex control of rSNA, and heart rate (HR) were assessed. Thiobarbituric acid reactive substances and glutathione were measured as indicators of systemic oxidative stress. Angiostensin-converting enzyme (ACE), ACE2, and angiotensinogen were evaluated in clipped and unclipped kidneys as also urinary angiotensinogen and plasma renin activity. Angiotensinogen, plasma renin activity (PRA) and angiotensin-converting enzyme (ACE) and ACE2 in clipped and unclipped kidneys were evaluated. RESULTS High-sodium diet did not change systemic oxidative stress, and basal values of MAP, HR, or rSNA; however, increased renal (-0.7±0.2 vs. -1.5±0.1 spikes/s/mm Hg) and cardiac (-0.9±0.14 vs. -1.5±0.14 bpm/mm Hg) baroreceptor reflex sensitivity in 2K1C rats. Although there was no alteration in PRA, a high-salt diet significantly decreased urinary angiotensinogen, ACE, and ACE2 expressions in the clipped and unclipped kidneys. CONCLUSIONS Increased arterial baroreceptor control associated with a suppression of the intrarenal RAS in the 2K1C rats on high-salt diet provide a salt-resistant effect on hypertension and sympathoexcitation in renovascular hypertensive rats.
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Affiliation(s)
- Caroline G Shimoura
- Cardiovascular Division-Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Gisele S Lincevicius
- Cardiovascular Division-Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Erika E Nishi
- Cardiovascular Division-Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Adriana C C Girardi
- Heart Institute (InCor) University of São Paulo Medical School, São Paulo, São Paulo, Brazil
| | - Karin A Simon
- Department of Biological Sciences, Universidade Federal de São Paulo, Diadema, Brazil
| | - Cassia T Bergamaschi
- Cardiovascular Division-Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Ruy R Campos
- Cardiovascular Division-Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil;
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11
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de Queiroz TM, Xia H, Filipeanu CM, Braga VA, Lazartigues E. α-Lipoic acid reduces neurogenic hypertension by blunting oxidative stress-mediated increase in ADAM17. Am J Physiol Heart Circ Physiol 2015; 309:H926-34. [PMID: 26254330 PMCID: PMC4591409 DOI: 10.1152/ajpheart.00259.2015] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 07/30/2015] [Indexed: 02/07/2023]
Abstract
We previously reported that type 2 angiotensin-converting enzyme (ACE2) compensatory activity is impaired by the disintegrin and metalloprotease 17 (ADAM17), and lack of ACE2 is associated with oxidative stress in neurogenic hypertension. To investigate the relationship between ADAM17 and oxidative stress, Neuro2A cells were treated with ANG II (100 nM) 24 h after vehicle or α-lipoic acid (LA, 500 μM). ADAM17 expression was increased by ANG II (120.5 ± 9.1 vs. 100.2 ± 0.8%, P < 0.05) and decreased after LA (69.0 ± 0.3 vs. 120.5 ± 9.1%, P < 0.05). In another set of experiments, LA reduced ADAM17 (92.9 ± 5.3 vs. 100.0 ± 11.2%, P < 0.05) following its overexpression. Moreover, ADAM17 activity was reduced by LA in ADAM17-overexpressing cells [109.5 ± 19.8 vs. 158.0 ± 20.0 fluorescence units (FU)·min(-1)·μg protein(-1), P < 0.05], in which ADAM17 overexpression increased oxidative stress (114.1 ± 2.5 vs. 101.0 ± 1.0%, P < 0.05). Conversely, LA-treated cells attenuated ADAM17 overexpression-induced oxidative stress (76.0 ± 9.1 vs. 114.1 ± 2.5%, P < 0.05). In deoxycorticosterone acetate (DOCA)-salt hypertensive mice, a model in which ADAM17 expression and activity are increased, hypertension was blunted by pretreatment with LA (119.0 ± 2.4 vs. 131.4 ± 2.2 mmHg, P < 0.05). In addition, LA improved dysautonomia and baroreflex sensitivity. Furthermore, LA blunted the increase in NADPH oxidase subunit expression, as well as the increase in ADAM17 and decrease in ACE2 activity in the hypothalamus of DOCA-salt hypertensive mice. Taken together, these data suggest that LA might preserve ACE2 compensatory activity by breaking the feedforward cycle between ADAM17 and oxidative stress, resulting in a reduction of neurogenic hypertension.
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Affiliation(s)
- Thyago M de Queiroz
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana; Department of Biotechnology, Federal University of Paraíba, João Pessoa, PB, Brazil
| | - Huijing Xia
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana; Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana; and
| | - Catalin M Filipeanu
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana; Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana; and
| | - Valdir A Braga
- Department of Biotechnology, Federal University of Paraíba, João Pessoa, PB, Brazil
| | - Eric Lazartigues
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana; Neurosciences Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana; Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana; and
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12
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Participation of the TRP channel in the cardiovascular effects induced by carvacrol in normotensive rat. Vascul Pharmacol 2015; 67-69:48-58. [PMID: 25869504 DOI: 10.1016/j.vph.2015.02.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 02/12/2015] [Accepted: 02/16/2015] [Indexed: 11/21/2022]
Abstract
Carvacrol has been described as an agonist/antagonist of different transient receptor potential (TRP) channels and voltage-dependent calcium channels (Cavs). The aim of this study was to evaluate the role of Cav and TRP channels following carvacrol stimulation. Initially, in mesenteric artery rings carvacrol relaxed phenylephrine-induced contractions. Furthermore, carvacrol inhibited contraction elicited by CaCl2 in depolarizing nominally without Ca2+ medium and antagonized the contractions induced by S(-)-Bay K 8644 and inhibited Ca2+ currents indicating the inhibition of Ca2+ influx through L-type Cav. Additionally, carvacrol antagonized the contractions induced by CaCl2 in the presence of nifedipine/Cyclopiazonic acid/phenylephrine or nifedipine/Cyclopiazonic acid/KCl 60, suggesting a possible inhibition of calcium influx by store operated channels (SOCs), receptor operated channels (ROCs) and/or TRP channels. Interestingly, among the TRP channel blockers used, the effect induced by carvacrol was attenuated by Mg2+ and potentiated by La3+ and Gd3+, suggesting that TRP channels are involved in relaxation induced by carvacrol. Monoterpene also induced hypotension and bradycardia in non-anesthetized normotensive rats and negative inotropic and chronotropic effects. In conclusion, these results suggest that the hypotensive effect of carvacrol is probably due to bradycardia and a peripheral vasodilatation that involves, at least, the inhibition of the Ca2+ influx through Cav and TRP channels.
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13
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Alves NFB, Porpino SKP, Monteiro MMO, Gomes ERM, Braga VA. Coconut oil supplementation and physical exercise improves baroreflex sensitivity and oxidative stress in hypertensive rats. Appl Physiol Nutr Metab 2015; 40:393-400. [PMID: 25659569 DOI: 10.1139/apnm-2014-0351] [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] [Indexed: 12/31/2022]
Abstract
The hypothesis that oral supplementation with virgin coconut oil (Cocos nucifera L.) and exercise training would improve impaired baroreflex sensitivity (BRS) and reduce oxidative stress in spontaneously hypertensive rats (SHR) was tested. Adult male SHR and Wistar Kyoto rats (WKY) were divided into 5 groups: WKY + saline (n = 8); SHR + saline (n = 8); SHR + coconut oil (2 mL·day(-1), n = 8); SHR + trained (n = 8); and SHR + trained + coconut oil (n = 8). Mean arterial pressure (MAP) was recorded and BRS was tested using phenylephrine (8 μg/kg, intravenous) and sodium nitroprusside (25 μg·kg(-1), intravenous). Oxidative stress was measured using dihydroethidium in heart and aorta. SHR + saline, SHR + coconut oil, and SHR + trained group showed higher MAP compared with WKY + saline (175 ± 6, 148 ± 6, 147 ± 7 vs. 113 ± 2 mm Hg; p < 0.05). SHR + coconut oil, SHR + trained group, and SHR + trained + coconut oil groups presented lower MAP compared with SHR + saline group (148 ± 6, 147 ± 7, 134 ± 8 vs. 175 ± 6 mm Hg; p < 0.05). Coconut oil combined with exercise training improved BRS in SHR compared with SHR + saline group (-2.47 ± 0.3 vs. -1.39 ± 0.09 beats·min(-1)·mm Hg(-1); p < 0.05). SHR + saline group showed higher superoxide levels when compared with WKY + saline (774 ± 31 vs. 634 ± 19 arbitrary units (AU), respectively; p < 0.05). SHR + trained + coconut oil group presented reduced oxidative stress compared with SHR + saline in heart (622 ± 16 vs. 774 ± 31 AU, p < 0.05). In aorta, coconut oil reduced oxidative stress in SHR compared with SHR + saline group (454 ± 33 vs. 689 ± 29 AU, p < 0.05). Oral supplementation with coconut oil combined with exercise training improved impaired BRS and reduced oxidative stress in SHR.
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Affiliation(s)
- Naiane F B Alves
- Biotechnology Center, Federal University of Paraíba, João Pessoa, PB 58051-900, Brazil
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14
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Chu CP, Cui BR, Kannan H, Qiu DL. Alterations in the baroreceptor-heart rate reflex in conscious inbred polydipsic (STR/N) mice. Physiol Res 2014; 64:173-82. [PMID: 25317689 DOI: 10.33549/physiolres.932820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
STR/N is an inbred strain of mice which is known to exhibit extreme polydipsia and polyuria. We previously found central administration of angiotensin II enhanced cardiovascular responses in STR/N mice than normal mice, suggesting that STR/N mice might exhibit different cardiovascular responses. Therefore, in this study, we investigated daily mean arterial blood pressure and heart rate, and changes in the baroreceptor-heart rate reflex in conscious STR/N mice and control (ICR) mice. We found that variability in daily mean arterial blood pressure and heart rate was significantly larger in STR/N mice than in ICR mice (p<0.05). There was a stronger response to phenylephrine (PE) in STR/N mice than in ICR mice. For baroreceptor reflex sensitivity, in the rapid response period, the slopes of PE and sodium nitroprusside (SNP) were more negative in STR/N mice than in ICR mice. In the later period, the slopes of PE and SNP were negatively correlated between heart rate and blood pressure in ICR mice, but their slopes were positively correlated in STR/N mice. These results indicated that STR/N mice exhibited the different cardiovascular responses than ICR mice, suggesting that the dysfunction of baroreceptor reflex happened in conscious STR/N mice.
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Affiliation(s)
- C P Chu
- Cellular Function Research Center, Yanbian University, Yanji City, Jilin Province, China. ;
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Hamza SM, Dyck JRB. Systemic and renal oxidative stress in the pathogenesis of hypertension: modulation of long-term control of arterial blood pressure by resveratrol. Front Physiol 2014; 5:292. [PMID: 25140155 PMCID: PMC4122172 DOI: 10.3389/fphys.2014.00292] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 07/19/2014] [Indexed: 12/12/2022] Open
Abstract
Hypertension affects over 25% of the global population and is associated with grave and often fatal complications that affect many organ systems. Although great advancements have been made in the clinical assessment and treatment of hypertension, the cause of hypertension in over 90% of these patients is unknown, which hampers the development of targeted and more effective treatment. The etiology of hypertension involves multiple pathological processes and organ systems, however one unifying feature of all of these contributing factors is oxidative stress. Once the body's natural anti-oxidant defense mechanisms are overwhelmed, reactive oxygen species (ROS) begin to accumulate in the tissues. ROS play important roles in normal regulation of many physiological processes, however in excess they are detrimental and cause widespread cell and tissue damage as well as derangements in many physiological processes. Thus, control of oxidative stress has become an attractive target for pharmacotherapy to prevent and manage hypertension. Resveratrol (trans-3,5,4'-Trihydroxystilbene) is a naturally occurring polyphenol which has anti-oxidant effects in vivo. Many studies have shown anti-hypertensive effects of resveratrol in different pre-clinical models of hypertension, via a multitude of mechanisms that include its function as an anti-oxidant. However, results have been mixed and in some cases resveratrol has no effect on blood pressure. This may be due to the heavy emphasis on peripheral vasodilator effects of resveratrol and virtually no investigation of its potential renal effects. This is particularly troubling in the arena of hypertension, where it is well known and accepted that the kidney plays an essential role in the long term regulation of arterial pressure and a vital role in the initiation, development and maintenance of chronic hypertension. It is thus the focus of this review to discuss the potential of resveratrol as an anti-hypertensive treatment via amelioration of oxidative stress within the framework of the fundamental physiological principles of long term regulation of arterial blood pressure.
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Affiliation(s)
- Shereen M. Hamza
- Department of Pediatrics, Cardiovascular Research Centre, University of AlbertaEdmonton, AB, Canada
| | - Jason R. B. Dyck
- Department of Pediatrics, Cardiovascular Research Centre, University of AlbertaEdmonton, AB, Canada
- Department of Pharmacology, Cardiovascular Research Centre, University of AlbertaEdmonton, AB, Canada
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Dantas BPV, Ribeiro TP, Assis VL, Furtado FF, Assis KS, Alves JS, Silva TM, Camara CA, França-Silva MS, Veras RC, Medeiros IA, Alencar JL, Braga VA. Vasorelaxation induced by a new naphthoquinone-oxime is mediated by NO-sGC-cGMP pathway. Molecules 2014; 19:9773-85. [PMID: 25006785 PMCID: PMC6270866 DOI: 10.3390/molecules19079773] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 06/21/2014] [Accepted: 06/23/2014] [Indexed: 11/16/2022] Open
Abstract
It has been established that oximes cause endothelium-independent relaxation in blood vessels. In the present study, the cardiovascular effects of the new oxime 3-hydroxy-4–(hydroxyimino)-2-(3-methylbut-2-enylnaphtalen-1(4H)-one (OximeS1) derived from lapachol were evaluated. In normotensive rats, administration of Oxime S1 (10, 15, 20 and 30 mg/Kg, i.v.) produced dose-dependent reduction in blood pressure. In isolated aorta and superior mesenteric artery rings, Oxime S1 induced endothelium-independent and concentration-dependent relaxations (10−8 M to 10−4 M). In addition, Oxime S1-induced vasorelaxations were attenuated by hydroxocobalamin or methylene blue in aorta and by PTIO or ODQ in mesenteric artery rings, suggesting a role for the nitric oxide (NO) pathway. Additionally, Oxime S1 (30 and 100 µM) significantly increased NO concentrations (13.9 ± 1.6 nM and 17.9 ± 4.1 nM, respectively) measured by nitric oxide microsensors. Furthermore, pre-contraction with KCl (80 mM) prevented Oxime S1-derived vasorelaxation in endothelium-denuded aortic rings. Of note, combined treatment with potassium channel inhibitors also reduced Oxime S1-mediated vasorelaxation suggesting a role for potassium channels, more precisely Kir, Kv and KATP channels. We observed the involvement of BKCa channels in Oxime S1-induced relaxation in mesenteric artery rings. In conclusion, these data suggest that the Oxime S1 induces hypotension and vasorelaxation via NO pathway by activating soluble guanylate cyclase (sGC) and K+ channels.
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Affiliation(s)
- Bruna P. V. Dantas
- Biotechnology Center, Federal University of Paraíba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (B.P.V.D.); (T.P.R); (V.L.A.); (F.F.F.); (K.S.A.); (M.S.F.-S.); (R.C.V.); (I.A.M.); (J.L.A.)
| | - Thaís P. Ribeiro
- Biotechnology Center, Federal University of Paraíba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (B.P.V.D.); (T.P.R); (V.L.A.); (F.F.F.); (K.S.A.); (M.S.F.-S.); (R.C.V.); (I.A.M.); (J.L.A.)
| | - Valéria L. Assis
- Biotechnology Center, Federal University of Paraíba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (B.P.V.D.); (T.P.R); (V.L.A.); (F.F.F.); (K.S.A.); (M.S.F.-S.); (R.C.V.); (I.A.M.); (J.L.A.)
| | - Fabíola F. Furtado
- Biotechnology Center, Federal University of Paraíba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (B.P.V.D.); (T.P.R); (V.L.A.); (F.F.F.); (K.S.A.); (M.S.F.-S.); (R.C.V.); (I.A.M.); (J.L.A.)
| | - Kívia S. Assis
- Biotechnology Center, Federal University of Paraíba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (B.P.V.D.); (T.P.R); (V.L.A.); (F.F.F.); (K.S.A.); (M.S.F.-S.); (R.C.V.); (I.A.M.); (J.L.A.)
| | - Jeziane S. Alves
- Molecular Sciences Department, Federal Rural University of Pernambuco, Recife, PE 52171-900, Brazil; E-Mails: (J.S.A.); (T.M.S.S.); (C.A.C.)
| | - Tania M.S. Silva
- Molecular Sciences Department, Federal Rural University of Pernambuco, Recife, PE 52171-900, Brazil; E-Mails: (J.S.A.); (T.M.S.S.); (C.A.C.)
| | - Celso A. Camara
- Molecular Sciences Department, Federal Rural University of Pernambuco, Recife, PE 52171-900, Brazil; E-Mails: (J.S.A.); (T.M.S.S.); (C.A.C.)
| | - Maria S. França-Silva
- Biotechnology Center, Federal University of Paraíba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (B.P.V.D.); (T.P.R); (V.L.A.); (F.F.F.); (K.S.A.); (M.S.F.-S.); (R.C.V.); (I.A.M.); (J.L.A.)
| | - Robson C. Veras
- Biotechnology Center, Federal University of Paraíba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (B.P.V.D.); (T.P.R); (V.L.A.); (F.F.F.); (K.S.A.); (M.S.F.-S.); (R.C.V.); (I.A.M.); (J.L.A.)
| | - Isac A. Medeiros
- Biotechnology Center, Federal University of Paraíba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (B.P.V.D.); (T.P.R); (V.L.A.); (F.F.F.); (K.S.A.); (M.S.F.-S.); (R.C.V.); (I.A.M.); (J.L.A.)
| | - Jacicarlos L. Alencar
- Biotechnology Center, Federal University of Paraíba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (B.P.V.D.); (T.P.R); (V.L.A.); (F.F.F.); (K.S.A.); (M.S.F.-S.); (R.C.V.); (I.A.M.); (J.L.A.)
| | - Valdir A. Braga
- Biotechnology Center, Federal University of Paraíba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (B.P.V.D.); (T.P.R); (V.L.A.); (F.F.F.); (K.S.A.); (M.S.F.-S.); (R.C.V.); (I.A.M.); (J.L.A.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +55-083-3216-7173; Fax: +55-083-3216-7511
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Braga VA. Could AT1 receptor activation increase antioxidant defense to prevent salt-induced vascular dysfunction of 2 kidney-1 clip hypertensive rats? Am J Hypertens 2014; 27:638-9. [PMID: 24614862 DOI: 10.1093/ajh/hpu014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Valdir A Braga
- Department of Biotechnology, Biotechnology Center, Federal University of Paraiba, João Pessoa, PB, Brazil
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de Queiroz TM, Monteiro MMO, Braga VA. Angiotensin-II-derived reactive oxygen species on baroreflex sensitivity during hypertension: new perspectives. Front Physiol 2013; 4:105. [PMID: 23717285 PMCID: PMC3651964 DOI: 10.3389/fphys.2013.00105] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 04/24/2013] [Indexed: 12/12/2022] Open
Abstract
Hypertension is a multifactorial disorder, which has been associated with the reduction in baroreflex sensitivity (BRS) and autonomic dysfunction. Several studies have revealed that increased reactive oxygen species (ROS) generated by nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase, following activation of type 1 receptor (AT1R) by Angiotensin-(Ang) II, the main peptide of the Renin–Angiotensin–Aldosterone System (RAAS), is the central mechanism involved in Ang-II-derived hypertension. In the present review, we will discuss the role of Ang II and oxidative stress in hypertension, the relationship between the BRS and the genesis of hypertension and how the oxidative stress triggers baroreflex dysfunction in several models of hypertension. Finally, we will describe some novel therapeutic drugs for improving the BRS during hypertension.
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Affiliation(s)
- Thyago M de Queiroz
- Department of Biotechnology, Biotechnology Center, Federal University of Paraiba João Pessoa, Brazil
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Mendes-Junior LDG, Monteiro MMDO, Carvalho ADS, de Queiroz TM, Braga VDA. Oral supplementation with the rutin improves cardiovagal baroreflex sensitivity and vascular reactivity in hypertensive rats. Appl Physiol Nutr Metab 2013; 38:1099-106. [PMID: 24053516 DOI: 10.1139/apnm-2013-0091] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The hypothesis that oral supplementation with the flavonoid rutin improves baroreflex sensitivity and vascular reactivity in hypertensive (2-kidney-1-clip (2K1C)) rats was tested. Sixty-four rats were divided in 4 groups: sham + saline; sham + rutin; 2K1C + saline, and 2K1C + rutin. Six weeks after 2K1C surgery, the animals were treated with saline or rutin (40 mg·kg(-1)·day(-1)) by gavage for 7 days. Baroreflex sensitivity test using phenylephrine (8 μg·kg(-1), iv) and sodium nitroprusside (25 μg·kg(-1), iv), vascular reactivity, and thiobarbituric acid reactive substances assay were performed. Baroreflex sensitivity in hypertensive rats was impaired and compared with sham (-2.77 ± 0.15 vs. -1.53 ± 0.27 beats·min(-1)·mm Hg(-1); n = 8; p < 0.05). Oral supplementation with rutin restored baroreflex sensitivity in 2K1C rats (-2.40 ± 0.24 vs. -2.77 ± 0.15 beats·min(-1)·mm Hg(-1); n = 8; p > 0.05). Besides, hypertensive rats have greater contraction to phenylephrine (129.49% ± 4.46% vs. 99.50% ± 11.36%; n = 8; p < 0.05), which was restored by rutin (99.10% ± 1.77% vs. 99.50% ± 11.36%; n = 8; p > 0.05). Furthermore, vasorelaxation to acetylcholine was diminished in hypertensive rats (96.42% ± 2.80% vs. 119.35% ± 5.60%; n = 8; p < 0.05), which was also restored by rutin (117.55% ± 6.94% vs. 119.35% ± 5.60%; n = 8; p > 0.05). Finally, oxidative stress was greater in hypertensive rats (1.54 ± 0.12 vs. 0.53 ± 0.12 nmol MDA·mL(-1); n = 8; p < 0.05) and rutin supplementation significantly decreased oxidative stress in those animals (0.70 ± 0.13 vs. 1.54 ± 0.12 nmol MDA·mL(-1); n = 8; p < 0.05). We concluded that oral supplementation with rutin restores impaired baroreflex sensitivity and vascular reactivity in hypertensive rats by decreasing oxidative stress.
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Guimarães DD, Carvalho CC, Braga VA. Scavenging of NADPH oxidase-derived superoxide anions improves depressed baroreflex sensitivity in spontaneously hypertensive rats. Clin Exp Pharmacol Physiol 2012; 39:373-8. [PMID: 22283703 DOI: 10.1111/j.1440-1681.2012.05679.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In pathological conditions, such as hypertension, there is impairment in the autonomic control of blood pressure resulting in changes in baroreflex sensitivity. In the present study we tested the hypothesis that acute superoxide scavenging would restore the depressed baroreflex sensitivity (BRS) in spontaneously hypertensive rats (SHR). Male 10-week-old SHR (n = 14) and their controls (Wistar-Kyoto (WKY) rats; n = 14) underwent femoral artery and vein catheterization for conscious blood pressure recording and drug administration. The BRS was obtained by the drug-induced method using phenylephrine (8 μg/kg, i.v.) and sodium nitroprusside (25 μg/kg, i.v.) before and after the administration of tiron (30 mg/kg, i.v.), a superoxide dismutase mimetic, or apocynin (30 μg/kg), an NADPH oxidase inhibitor. Spontaneously hypertensive rats was significantly hypertensive compared with WKY rats (160 ± 7 vs 105 ± 2 mmHg, respectively). However, there was no significant difference in heart rate between the two groups (388 ± 10 vs 370 ± 20 b.p.m.). In addition, SHR exhibited a diminished BRS compared with WKY rats (-1.34 ± 0.11 vs -2.91 ± 0.20 b.p.m./mmHg, respectively). Administration of tiron improved BRS in SHR (from -1.34 ± 0.11 to 2.26 ± 0.21 b.p.m./mmHg), as did apocynin (to -2.14 ± 0.23 b.p.m./mmHg). Serum samples from SHR (n = 20) and WKY rats (n = 20) were collected for thiobarbituric acid-reactive substances assays before and after tiron or apocynin to confirm the reduction in oxidative stress. There was considerably greater oxidative stress in SHR compared with WKY rats (36.2 ± 3.0 vs 13.3 ± 2.6 nmol/L, respectively). Both apocynin and tiron treatment reduced the oxidative stress in SHR (from 36.2 ± 3.0 to 21.5 ± 3.0 nmol/L and from 37.2 ± 3.9 to 21.9 ± 1.6 nmol/L, respectively). The data suggest that acute scavenging of NADPH oxidase-derived superoxide improves baroreflex sensitivity in SHR.
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Affiliation(s)
- D D Guimarães
- Biotechnology Center, Federal University of Paraíba, João Pessoa, Brazil
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α-lipoic acid reduces hypertension and increases baroreflex sensitivity in renovascular hypertensive rats. Molecules 2012; 17:13357-67. [PMID: 23143148 PMCID: PMC6268197 DOI: 10.3390/molecules171113357] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 10/26/2012] [Accepted: 10/31/2012] [Indexed: 02/07/2023] Open
Abstract
Renovascular hypertension has robust effects on control of blood pressure, including an impairment in baroreflex mechanisms, which involves oxidative stress. Although α-lipoic acid (LA) has been described as a potent antioxidant, its effect on renovascular hypertension and baroreflex sensitivity (BRS) has not been investigated. In the present study we analyzed the effects caused by chronic treatment with LA on blood pressure, heart rate and baroreflex sensitivity (sympathetic and parasympathetic components) in renovascular hypertensive rats. Male Wistar rats underwent 2-Kidney-1-Clip (2K1C) or sham surgery and were maintained untouched for four weeks to develop hypertension. Four weeks post-surgery, rats were treated with LA (60 mg/kg) or saline for 14 days orally. On the 15th day mean arterial pressure (MAP) and heart rate (HR) were recorded. In addition, baroreflex sensitivity test using phenylephrine (8 µg/kg, i.v.) and sodium nitroprusside (25 µg/kg, i.v.) was performed. Chronic treatment with LA decreased blood pressure in hypertensive animals; however, no significant changes in baseline HR were observed. Regarding baroreflex, LA treatment increased the sensitivity of both the sympathetic and parasympathetic components. All parameters studied were not affected by treatment with LA in normotensive animals. Our data suggest that chronic treatment with LA promotes antihypertensive effect and improves baroreflex sensitivity in rats with renovascular hypertension.
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França-Silva MS, Monteiro MMO, Queiroz TM, Santos AF, Athayde-Filho PF, Braga VA. The new nitric oxide donor 2-nitrate-1,3-dibuthoxypropan alters autonomic function in spontaneously hypertensive rats. Auton Neurosci 2012; 171:28-35. [PMID: 23141524 DOI: 10.1016/j.autneu.2012.10.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 09/11/2012] [Accepted: 10/12/2012] [Indexed: 10/27/2022]
Abstract
Previously, we found that the nitrate synthesized from glycerin, 2-nitrate-1,3-dibuthoxypropan (NDBP), increased NO levels in rat aortic smooth muscle cells, inducing vasorelaxation in mesenteric artery. However, its effects on blood pressure and heart rate as well as on autonomic function were not investigated. This study evaluated the action of NDBP on these cardiovascular parameters in spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats. We found that NDBP causes a biphasic response: hypotension and bradycardia followed by hypertension and tachycardia in WKY and SHR rats. Atropine (2mg/kg) blunted the hypotension induced by NDBP (15 mg/kg) in WKY and SHR (-75 ± 9 vs -12 ± 3 mmHg, n=6; -101 ± 6 vs -7 ± 2 bpm, n=6; respectively, p<0.05) and the pressor response to the compound was potentiated. Furthermore, vagotomy reduced the bradycardia in WKY and SHR (-136 ± 8 vs -17 ± 2, n=4, p<0.05; -141 ± 9 vs -8 ± 2, n=6, p<0.05). Moreover, hexamethonium (30 mg/kg) reduced both bradycardia (-278 ± 23 vs -48 ± 3 in WKY; -285 ± 16 vs -27 ± 19 in SHR, n=4; p<0.05) and pressor response (28 ± 8 vs -9 ± 5-WKY, n=6; 42 ± 7 vs -19 ± 8-SHR, n=5; p<0.05). In addition, administration of methylene blue (4 mg/kg) attenuated the hypotensive and bradycardic responses to the NDBP in all groups. In conclusion, NDBP induces bradycardia by direct vagal stimulation and pressor response by increasing sympathetic outflow to the periphery.
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Monteiro MMO, França-Silva MS, Alves NFB, Porpino SKP, Braga VA. Quercetin improves baroreflex sensitivity in spontaneously hypertensive rats. Molecules 2012; 17:12997-3008. [PMID: 23117438 PMCID: PMC6269113 DOI: 10.3390/molecules171112997] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 10/26/2012] [Accepted: 10/31/2012] [Indexed: 02/07/2023] Open
Abstract
Quercetin is a well-known antioxidant. Here, we investigated the effects of treatment with quercetin on mean arterial pressure (MAP), heart rate (HR) and baroreflex sensitivity (BRS) in spontaneously hypertensive rats (SHR). SHR and their controls (WKY) were orally treated with quercetin (2, 10 or 25 mg/kg/day) or saline for seven days. On the 8th day, MAP and HR were recorded. BRS was tested using phenylephrine (8 mg/kg, i.v.) and sodium nitroprusside (25 mg/kg, i.v.). Oxidative stress was measured by tiobarbituric acid reactive species assay. The doses of 10 (n = 8) and 25 mg/kg (n = 8) were able to decrease the MAP in SHR (n = 9) (163 ± 4 and 156 ± 5 vs. 173 ± 6, respectively, p < 0.05) but not in WKY (117 ± 1 and 118 ± 2 vs. 113 ± 1, respectively, p < 0.05). The dose of 25 mg/kg/day increased the sensitivity of parasympathetic component of the baroreflex (−2.47 ± 0.31 vs. −1.25 ± 0.8 bpm/mmHg) and decreased serum oxidative stress in SHR (2.04 ± 0.17 vs. 3.22 ± 0.37 nmol/mL, n = 6). Our data suggest that treatment with quercetin reduces hypertension and improves BRS in SHR via reduction in oxidative stress.
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Angiotensin II-derived reactive oxygen species underpinning the processing of the cardiovascular reflexes in the medulla oblongata. Neurosci Bull 2011; 27:269-74. [PMID: 21788998 DOI: 10.1007/s12264-011-1529-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The brainstem is a major site in the central nervous system involved in the processing of the cardiovascular reflexes such as the baroreflex and the peripheral chemoreflex. The nucleus tractus solitarius and the rostral ventrolateral medulla are 2 important brainstem nuclei, and they play pivotal roles in autonomic cardiovascular regulation. Angiotensin II is one of the neurotransmitters involved in the processing of the cardiovascular reflexes within the brainstem. It is well-known that one of the mechanisms by which angiotensin II exerts its effect is via the activation of pathways that generate reactive oxygen species (ROS). In the central nervous system, ROS are reported to be involved in several pathological diseases such as hypertension, heart failure and sleep apnea. However, little is known about the role of ROS in the processing of the cardiovascular reflexes within the brainstem. The present review mainly discussed some recent findings documenting a role for ROS in the processing of the baroreflex and the peripheral chemoreflex in the brainstem.
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Abstract
Blood-borne angiotensin-II (Ang-II) has profound effects in the brain. We tested the hypothesis that Ang-II-dependent hypertension involves differential Ang-II type I (AT1) receptors expression in the subfornical organ (SFO) and the rostral ventrolateral medulla (RVLM). Male Wistar rats were implanted with 14-day osmotic minipump filled with Ang-II (150 ng/kg/min) or saline. AT1 receptor mRNA levels were detected in the SFO and RVLM by reverse transcription-polymerase chain reaction (RT-PCR). Ang-II caused hypertension (134 ± 10 mmHg vs. 98 ± 9 mmHg, n = 9, p < 0.05). RT-PCR revealed that Ang-II infusion induced increased AT1 receptor mRNA levels in RVLM and decreased in SFO. Our data suggest that Ang-II-induced hypertension involves differential expression of brain AT1 receptors.
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Affiliation(s)
- Valdir A Braga
- Veterinary Sciences Department, Center for Agrarian Sciences, Federal University of Paraíba, Areia, PB 58397-000, Brazil.
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26
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Queiroz TM, Machado NT, Furtado FF, Oliveira-Filho AA, Alustau MC, Figueiredo CS, Miranda GEC, Barbosa-Filho JM, Braga VA, Medeiros IA. Vasorelaxation, induced by Dictyota pulchella (Dictyotaceae), a brown alga, is mediated via inhibition of calcium influx in rats. Mar Drugs 2011; 9:2075-2088. [PMID: 22073010 PMCID: PMC3210619 DOI: 10.3390/md9102075] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 10/13/2011] [Accepted: 10/17/2011] [Indexed: 01/05/2023] Open
Abstract
This study aimed to investigate the cardiovascular effects elicited by Dictyota pulchella, a brown alga, using in vivo and in vitro approaches. In normotensive conscious rats, CH(2)Cl(2)/MeOH Extract (CME, 5, 10, 20 and 40 mg/kg) from Dictyota pulchella produced dose-dependent hypotension (-4 ± 1; -8 ± 2; -53 ± 8 and -63 ± 3 mmHg) and bradycardia (-8 ± 6; -17 ± 11; -257 ± 36 and -285 ± 27 b.p.m.). In addition, CME and Hexane/EtOAc Phase (HEP) (0.01-300 μg/mL) from Dictyota pulchella induced a concentration-dependent relaxation in phenylephrine (Phe, 1 μM)-pre-contracted mesenteric artery rings. The vasorelaxant effect was not modified by the removal of the vascular endothelium or pre-incubation with KCl (20 mM), tetraethylammonium (TEA, 3 mM) or tromboxane A(2) agonist U-46619 (100 nM). Furthermore, CME and HEP reversed CaCl(2)-induced vascular contractions. These results suggest that both CME and HEP act on the voltage-operated calcium channel in order to produce vasorelaxation. In addition, CME induced vasodilatation after the vessels have been pre-contracted with L-type Ca(2+) channel agonist (Bay K 8644, 200 nM). Taken together, our data show that CME induces hypotension and bradycardia in vivo and that both CME and HEP induce endothelium-independent vasodilatation in vitro that seems to involve the inhibition of the Ca(2+) influx through blockade of voltage-operated calcium channels.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Animals
- Biological Products/pharmacology
- Calcium Channel Blockers/pharmacology
- Calcium Channels/drug effects
- Dose-Response Relationship, Drug
- Male
- Muscle, Smooth, Vascular/drug effects
- Phaeophyceae/chemistry
- Phenylephrine/pharmacology
- Potassium Chloride/pharmacology
- Rats
- Rats, Wistar
- Tetraethylammonium/pharmacology
- Vasodilation/drug effects
- Vasodilator Agents/pharmacology
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Affiliation(s)
- Thyago M. Queiroz
- Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (T.M.Q.); (N.T.M.); (F.F.F.); (A.A.O.-F); (M.C.A); (C.S.F.); (G.E.C.M.); (J.M.B.-F.); (I.A.M.)
| | - Natália T. Machado
- Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (T.M.Q.); (N.T.M.); (F.F.F.); (A.A.O.-F); (M.C.A); (C.S.F.); (G.E.C.M.); (J.M.B.-F.); (I.A.M.)
| | - Fabíola F. Furtado
- Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (T.M.Q.); (N.T.M.); (F.F.F.); (A.A.O.-F); (M.C.A); (C.S.F.); (G.E.C.M.); (J.M.B.-F.); (I.A.M.)
| | - Abrahão A. Oliveira-Filho
- Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (T.M.Q.); (N.T.M.); (F.F.F.); (A.A.O.-F); (M.C.A); (C.S.F.); (G.E.C.M.); (J.M.B.-F.); (I.A.M.)
| | - Maria C. Alustau
- Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (T.M.Q.); (N.T.M.); (F.F.F.); (A.A.O.-F); (M.C.A); (C.S.F.); (G.E.C.M.); (J.M.B.-F.); (I.A.M.)
| | - Camila S. Figueiredo
- Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (T.M.Q.); (N.T.M.); (F.F.F.); (A.A.O.-F); (M.C.A); (C.S.F.); (G.E.C.M.); (J.M.B.-F.); (I.A.M.)
| | - George E. C. Miranda
- Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (T.M.Q.); (N.T.M.); (F.F.F.); (A.A.O.-F); (M.C.A); (C.S.F.); (G.E.C.M.); (J.M.B.-F.); (I.A.M.)
| | - José M. Barbosa-Filho
- Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (T.M.Q.); (N.T.M.); (F.F.F.); (A.A.O.-F); (M.C.A); (C.S.F.); (G.E.C.M.); (J.M.B.-F.); (I.A.M.)
| | - Valdir A. Braga
- Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (T.M.Q.); (N.T.M.); (F.F.F.); (A.A.O.-F); (M.C.A); (C.S.F.); (G.E.C.M.); (J.M.B.-F.); (I.A.M.)
| | - Isac A. Medeiros
- Biotechnology Center, Federal University of Paraiba, João Pessoa, PB 58.051-900, Brazil; E-Mails: (T.M.Q.); (N.T.M.); (F.F.F.); (A.A.O.-F); (M.C.A); (C.S.F.); (G.E.C.M.); (J.M.B.-F.); (I.A.M.)
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Braga VA, Medeiros IA, Ribeiro TP, França-Silva MS, Botelho-Ono MS, Guimarães DD. Angiotensin-II-induced reactive oxygen species along the SFO-PVN-RVLM pathway: implications in neurogenic hypertension. Braz J Med Biol Res 2011; 44:871-6. [PMID: 21755262 DOI: 10.1590/s0100-879x2011007500088] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 06/16/2011] [Indexed: 02/07/2023] Open
Abstract
Neurogenic hypertension has been the subject of extensive research worldwide. This review is based on the premise that some forms of neurogenic hypertension are caused in part by the formation of angiotensin-II (Ang-II)-induced reactive oxygen species along the subfornical organ-paraventricular nucleus of the hypothalamus-rostral ventrolateral medulla pathway (SFO-PVN-RVLM pathway). We will discuss the recent contribution of our laboratory and others regarding the mechanisms by which neurons in the SFO (an important circumventricular organ) are activated by Ang-II, how the SFO communicates with two other important areas involved in sympathetic activity regulation (PVN and RVLM) and how Ang-II-induced reactive oxygen species participate along the SFO-PVN-RVLM pathway in the pathogenesis of neurogenic hypertension.
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Affiliation(s)
- V A Braga
- Laboratório de Tecnologia Farmacêutica, Universidade Federal da Paraíba, João Pessoa, PB, Brasil.
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Subramanian M, Balasubramanian P, Garver H, Northcott C, Zhao H, Haywood JR, Fink GD, MohanKumar SMJ, MohanKumar PS. Chronic estradiol-17β exposure increases superoxide production in the rostral ventrolateral medulla and causes hypertension: reversal by resveratrol. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1560-8. [PMID: 21411770 DOI: 10.1152/ajpregu.00020.2011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Women are exposed to estrogen in several forms, such as oral contraceptive pills and hormone replacement therapy. Although estrogen was believed to be cardioprotective, lately, its beneficial effects are being questioned. Recent studies indicate that oxidative stress in the rostral ventrolateral medulla (RVLM) may play a role in the development of hypertension. Therefore, we hypothesized that chronic exposure to low levels of estradiol-17β (E(2)) leads to hypertension in adult-cycling female Sprague Dawley (SD) rats potentially through generation of superoxide in the RVLM. To test this hypothesis, young adult (3 or 4 mo old) female SD rats were either sham-implanted or implanted (subcutaneously) with slow-release E(2) pellets (20 ng/day) for 90 days. A group of control and E(2)-treated animals were fed lab chow or chow containing resveratrol (0.84 g/kg of chow), an antioxidant. Rats were implanted with telemeters to continuously monitor blood pressure (BP) and heart rate (HR). At the end of treatment, the RVLM was isolated for measurements of superoxide. E(2) treatment significantly increased mean arterial pressure (mmHg) and HR (beats/min) compared with sham rats (119.6 ± 0.8 vs. 105.1 ± 0.7 mmHg and 371.7 ± 1.5 vs. 354.4 ± 1.3 beats/min, respectively; P < 0.0001). Diastolic and systolic BP were significantly increased in E(2)-treated rats compared with control animals. Superoxide levels in the RVLM increased significantly in the E(2)-treated group (0.833 ± 0.11 nmol/min·mg) compared with control (0.532 ± 0.04 nmol/min·mg; P < 0.05). Treatment with resveratrol reversed the E(2)-induced increases in BP and superoxide levels in the RVLM. In conclusion, these findings support the hypothesis that chronic exposure to low levels of E(2) induces hypertension and increases superoxide levels in the RVLM and that this effect can be reversed by resveratrol treatment.
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Affiliation(s)
- Madhan Subramanian
- Department of Pathobiology and Diagnostic Investigation, Colleges of Veterinary, Osteopathic and Human Medicine, Michigan State University, East Lansing, 48824, USA
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29
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Nunes FC, Braga VA. Chronic angiotensin II infusion modulates angiotensin II type I receptor expression in the subfornical organ and the rostral ventrolateral medulla in hypertensive rats. J Renin Angiotensin Aldosterone Syst 2011; 12:440-5. [PMID: 21393361 DOI: 10.1177/1470320310394891] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Blood-borne angiotensin II (Ang II) has profound effects on the central nervous system, including regulation of vasopressin secretion and modulation of sympathetic outflow. However, the mechanism by which circulating Ang II affects the central nervous system remains largely unknown. We tested the hypothesis that increased circulating levels of Ang II activate angiotensin type I (AT1) receptors in the subfornical organ (SFO), increasing the Ang II signalling in the rostral ventrolateral medulla (RVLM). Male Wistar rats were subcutaneously implanted with two 14-day osmotic minipumps filled with Ang II (150 ng/kg/minute), Losartan (10mg/kg/day), or saline. In addition, AT1 receptor mRNA levels in the SFO and RVLM were detected by reverse transcription polymerase chain reaction (RT-PCR). Infusion of Ang II-induced hypertension (134 ± 10 mmHg vs 98 ± 9 mmHg, n = 9, p < 0.05), which was blunted by concomitant infusion of Losartan (105 ± 8 vs 134 ± 10 mmHg, n = 9, p < 0.05). In addition, hexamethonium produced a greater decrease in blood pressure in Ang II-infused rats. Real time PCR revealed that chronic Ang II infusion induced an increase in AT1 receptor mRNA levels in the RVLM and a decrease in the SFO. Taken together, using combined in vivo and molecular biology approaches, our data suggest that Ang II-induced hypertension is mediated by an increase in sympathetic nerve activity, which seems to involve up-regulation of AT1 receptors in the RVLM and down-regulation of AT1 receptors in the SFO.
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Affiliation(s)
- Fabíola C Nunes
- Veterinary Sciences Department, Center for Agrarian Sciences, Federal University of Paraíba, Areia, PB, Brazil
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30
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Giusti MF, Sato MA, Cardoso LM, Braga VA, Colombari E. Central antioxidant therapy inhibits parasympathetic baroreflex control in conscious rats. Neurosci Lett 2011; 489:115-8. [DOI: 10.1016/j.neulet.2010.11.077] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 11/30/2010] [Accepted: 11/30/2010] [Indexed: 02/07/2023]
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Allen AM. Role of angiotensin in the rostral ventrolateral medulla in the development and maintenance of hypertension. Curr Opin Pharmacol 2011; 11:117-23. [PMID: 21269877 DOI: 10.1016/j.coph.2010.12.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 12/13/2010] [Accepted: 12/23/2010] [Indexed: 02/07/2023]
Abstract
Whilst crucial for behavioural and homeostatic responses to environmental challenges, chronic elevation of sympathetic nervous system activity to specific vascular beds is associated with hypertension. Indeed such elevated activity may drive the increase in blood pressure seen in some people and in some experimental models of hypertension. This review discusses the neural circuitry involved in generating and modulating sympathetic efferent nerve activity, focusing on the premotor neurons of the rostral ventrolateral medulla. Neurons in the rostral ventrolateral medulla show altered responses to angiotensin II in experimental models of hypertension, suggesting that this might be an important node for interaction between these two systems that are crucial for regulation of blood pressure.
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Affiliation(s)
- Andrew M Allen
- Department of Physiology and Florey Neurosciences Institutes, University of Melbourne, Vic., 3010, Australia.
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Saeed A, DiBona GF, Marcussen N, Guron G. High-NaCl intake impairs dynamic autoregulation of renal blood flow in ANG II-infused rats. Am J Physiol Regul Integr Comp Physiol 2010; 299:R1142-9. [DOI: 10.1152/ajpregu.00326.2010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this study was to investigate dynamic autoregulation of renal blood flow (RBF) in ANG II-infused rats and the influence of high-NaCl intake. Sprague-Dawley rats received ANG II (250 ng·kg−1·min−1 sc) or saline vehicle (sham) for 14 days after which acute renal clearance experiments were performed during thiobutabarbital anesthesia. Rats ( n = 8–10 per group) were either on a normal (NNa; 0.4% NaCl)- or high (HNa; 8% NaCl)-NaCl diet. Separate groups were treated with 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (tempol; 1 M in drinking water). Transfer function analysis from arterial pressure to RBF in the frequency domain was used to examine the myogenic response (MR; 0.06–0.09 Hz) and the tubuloglomerular feedback mechanism (TGF; 0.03–0.06 Hz). MAP was elevated in ANG II-infused rats compared with sham groups ( P < 0.05). RBF in ANG II HNa was reduced vs. sham NNa and sham HNa (6.0 ± 0.3 vs. 7.9 ± 0.3 and 9.1 ± 0.3 ml·min−1·g kidney wt−1, P < 0.05). transfer function gain in ANG II HNa was significantly elevated in the frequency range of the MR (1.26 ± 0.50 dB, P < 0.05 vs. all other groups) and in the frequency range of the TGF (−0.02 ± 0.50 dB, P < 0.05 vs. sham NNa and sham HNa). Gain values in the frequency range of the MR and TGF were significantly reduced by tempol in ANG II-infused rats on HNa diet. In summary, the MR and TGF components of RBF autoregulation were impaired in ANG II HNa, and these abnormalities were attenuated by tempol, suggesting a pathogenetic role for superoxide in the impaired RBF autoregulatory response.
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Affiliation(s)
- Aso Saeed
- Department of Molecular and Clinical Medicine/Nephrology, Institute of Medicine, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Gerald F. DiBona
- Departments of Internal Medicine and Molecular Physiology and Biophysics, Department of Veterans Affairs Medical Center and University of Iowa Carver College of Medicine, Iowa City, Iowa; and
| | - Niels Marcussen
- Department of Pathology, Odense University Hospital, Odense, Denmark
| | - Gregor Guron
- Department of Molecular and Clinical Medicine/Nephrology, Institute of Medicine, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
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Cavalcante HMM, Ribeiro TP, Silva DF, Nunes XP, Barbosa-Filho JM, Diniz MFFM, Correia NA, Braga VA, Medeiros IA. Cardiovascular effects elicited by milonine, a new 8,14-dihydromorphinandienone alkaloid. Basic Clin Pharmacol Toxicol 2010; 108:122-30. [PMID: 20979594 DOI: 10.1111/j.1742-7843.2010.00631.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The mechanisms underlying the cardiovascular responses evoked by milonine (i.v.), an alkaloid, were investigated in rats. In normotensive rats, milonine injections produced hypotension and tachycardia, which were attenuated after N(w) -nitro-L-arginine methyl esther (L-NAME; 20 mg/kg, i.v.). In phenylephrine (10 μM), pre-contracted mesenteric artery rings, milonine (10⁻¹⁰ M to 3 × 10⁻⁴ M) caused a concentration-dependent relaxation (EC₅₀ = 1.1 × 10⁻⁶ M, E(max) = 100 ± 0.0%) and this effect was rightward shifted after either removal of the vascular endothelium (EC₅₀ = 1.6 × 10⁻⁵, p < 0.001), or after L-NAME 100 μM (EC₅₀ = 6.2 × 10⁻⁵, p < 0.001), hydroxocobalamin 30 μM (EC₅₀ = 1.1 × 10⁻⁴, p < 0.001) or ODQ 10 μM (EC₅₀ = 1.9 × 10⁻⁴ p < 0.001). In addition, in rabbit aortic endothelial cells, milonine increased NO₃⁻ levels. The relaxant effect induced by milonine was attenuated in the presence of KCl (20 mM), a modulator efflux K(+) (EC₅₀ = 1.2 × 10⁻⁵, p < 0.001), or different potassium channel blockers such as glibenclamide (10 μM) (EC₅₀ = 6.3 × 10⁻⁵, p < 0.001), TEA (1 mM) (EC₅₀ = 2.3 × 10⁻⁵ M, n = 6) or Charybdotoxin (0.2 μM) plus apamin (0.2 μM) (EC₅₀ = 3.9 × 10⁻⁴ M, n = 7). In addition, pre-contraction with high extracellular potassium concentration prevented milonine-induced vasorelaxation (EC₅₀ = 1.0 × 10⁻⁴, p < 0.001). Milonine also reduced CaCl₂ -induced contraction in Ca²(+) -free solution containing KCl (60 mM). In conclusion, using combined functional and biochemical approaches, we demonstrated that the hypotensive and vasorelaxant effects produced by milonine are, at least in part, mediated by the endothelium, likely via nitric oxide release, activation of nitric oxide-cGMP pathway and opening of K(+) channels.
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Nunes FC, Ribeiro TP, França-Silva MS, Medeiros IA, Braga VA. Superoxide scavenging in the rostral ventrolateral medulla blunts the pressor response to peripheral chemoreflex activation. Brain Res 2010; 1351:141-149. [DOI: 10.1016/j.brainres.2010.07.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Revised: 06/26/2010] [Accepted: 07/01/2010] [Indexed: 02/07/2023]
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35
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Acute superoxide scavenging restores depressed baroreflex sensitivity in renovascular hypertensive rats. Auton Neurosci 2010; 159:38-44. [PMID: 20719579 DOI: 10.1016/j.autneu.2010.07.025] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 06/26/2010] [Accepted: 07/27/2010] [Indexed: 11/22/2022]
Abstract
In some pathological conditions such as hypertension, there is an impairment in the autonomic control of blood pressure resulting in changes in baroreflex sensitivity. In the present study we tested the hypothesis that acute superoxide scavenging would restore the reduced baroreflex sensitivity in renovascular hypertension. Male Wistar rats underwent 2-Kidney-1-Clip (2K1C) or sham surgery and were maintained untouched for six weeks to develop hypertension. After six weeks, animals from the 2K1C group were hypertensive when compared to the sham group (165±9 vs. 108±7mm Hg, P<0.05). As a proof of principle for the hypertension model adopted, animals from the 2K1C group presented increased non-clipped kidney and cardiac mass index and reduced clipped kidney mass index. Regarding baroreflex, 2K1C rats presented diminished baroreflex sensitivity when compared to the sham group (2K1C+saline: -1.61±0.15 vs. sham+saline: -2.79±0.24bpm mm Hg(-1), p<0.05). Moreover, acute administration of Vitamin C (150mg/Kg, i.v.) restored baroreflex sensitivity in 2K1C rats (2K1C+Vit C: -3.08±0.37 vs. 2K1C+saline: -1.61±0.15bpm mm Hg(-1), p<0.05). Furthermore, administration of apocynin (30μg/Kg, i.v.), a NADPH oxidase inhibitor, also improved baroreflex sensitivity in the 2K1C group (2K1C+apocynin: -2.81±0.24 vs. 2K1C+saline: -1.61±0.15bpm mm Hg(-1), p<0.05). In addition, autonomic blockade with either methylatropine or propranolol reduced the changes in heart rate to the same extent in all groups suggesting that improved baroreflex sensitivity by antioxidants were mediated by improvement in autonomic function. Taken together, these data suggest that NADPH oxidase-derived reactive oxygen species are involved in the blunted baroreflex sensitivity in renovascular hypertension and that acute scavenging of superoxide restores baroreflex sensitivity.
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Toney GM, Pedrino GR, Fink GD, Osborn JW. Does enhanced respiratory-sympathetic coupling contribute to peripheral neural mechanisms of angiotensin II-salt hypertension? Exp Physiol 2010; 95:587-94. [PMID: 20228120 DOI: 10.1113/expphysiol.2009.047399] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hypertension caused by chronic infusion of angiotensin II (Ang II) in experimental animals is likely to be mediated, at least in part, by an elevation of ongoing sympathetic nerve activity (SNA). However, the contribution of SNA relative to non-neural mechanisms in mediating Ang II-induced hypertension is an area of intense debate and remains unresolved. We hypothesize that sympathoexcitatory actions of Ang II are directly related to the level of dietary salt intake. To test this hypothesis, chronically instrumented rats were placed on a 0.1 (low), 0.4 (normal) or 2.0% NaCl diet (high) and, following a control period, administered Ang II (150 ng kg(1) min(1), s.c.) for 10-14 days. The hypertensive response to Ang II was greatest in rats on the high-salt diet (Ang II-salt hypertension), which was associated with increased 'whole body' sympathetic activity as measured by noradrenaline spillover and ganglionic blockade. Indirect and direct measures of organ-specific SNA revealed a distinct 'sympathetic signature' in Ang II-salt rats characterized by increased SNA to the splanchnic vascular bed, transiently reduced renal SNA and no change in SNA to the hindlimbs. Electrophysiological experiments indicate that increased sympathetic outflow in Ang II-salt rats is unlikely to involve activation of rostral ventrolateral medulla (RVLM) vasomotor neurons with barosensitive cardiac rhythmic discharge. Instead, another set of RVLM neurons that discharge in discrete bursts have exaggerated spontaneous activity in rats with Ang II-salt hypertension. Although their discharge is not cardiac rhythmic at resting levels of arterial pressure, it nevertheless appears to be barosensitive. Therefore, these burst-firing RVLM neurons presumably serve a vasomotor function, consistent with their having axonal projections to the spinal cord. Bursting discharge of these neurons is respiratory rhythmic and driven by the respiratory network. Given that splanchnic SNA is strongly coupled to respiration, we hypothesize that enhanced central respiratory-vasomotor neuron coupling in the RVLM could be an important mechanism that contributes to exaggerated splanchnic sympathetic outflow in Ang II-salt hypertension. This hypothesis remains to be tested directly in future investigations.
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Affiliation(s)
- Glenn M Toney
- University of Minnesota, Department of Integrative Biology and Physiology, Room 6-125 Jackson Hall, Minneapolis, MN 55455, USA
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