1
|
Dangudubiyyam SV, Bosse B, Yadav P, Song R, Hofmann A, Mishra JS, Kumar S. Restoring Angiotensin Type 2 Receptor Function Reverses PFOS-Induced Vascular Hyper-Reactivity and Hypertension in Pregnancy. Int J Mol Sci 2023; 24:14180. [PMID: 37762482 PMCID: PMC10531530 DOI: 10.3390/ijms241814180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 09/07/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023] Open
Abstract
Perfluorooctane sulfonic acid (PFOS) exposure during pregnancy induces hypertension with decreased vasodilatory angiotensin type-2 receptor (AT2R) expression and impaired vascular reactivity and fetal weights. We hypothesized that AT2R activation restores the AT1R/AT2R balance and reverses gestational hypertension by improving vascular mechanisms. Pregnant Sprague-Dawley rats were exposed to PFOS through drinking water (50 μg/mL) from gestation day (GD) 4-20. Controls received drinking water with no detectable PFOS. Control and PFOS-exposed rats were treated with AT2R agonist Compound 21 (C21; 0.3 mg/kg/day, SC) from GD 15-20. In PFOS dams, blood pressure was higher, blood flow in the uterine artery was reduced, and C21 reversed these to control levels. C21 mitigated the heightened contraction response to Ang II and enhanced endothelium-dependent vasorelaxation in uterine arteries of PFOS dams. The observed vascular effects of C21 were correlated with reduced AT1R levels and increased AT2R and eNOS protein levels. C21 also increased plasma bradykinin production in PFOS dams and attenuated the fetoplacental growth restriction. These data suggest that C21 improves the PFOS-induced maternal vascular dysfunction and blood flow to the fetoplacental unit, providing preclinical evidence to support that AT2R activation may be an important target for preventing or treating PFOS-induced adverse maternal and fetal outcomes.
Collapse
Affiliation(s)
- Sri Vidya Dangudubiyyam
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA; (S.V.D.); (P.Y.); (R.S.); (A.H.); (J.S.M.)
- Endocrinology-Reproductive Physiology Program, University of Wisconsin, Madison, WI 53715, USA
| | - Bradley Bosse
- Department of Obstetrics and Gynecology, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53792, USA;
| | - Pankaj Yadav
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA; (S.V.D.); (P.Y.); (R.S.); (A.H.); (J.S.M.)
| | - Ruolin Song
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA; (S.V.D.); (P.Y.); (R.S.); (A.H.); (J.S.M.)
| | - Alissa Hofmann
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA; (S.V.D.); (P.Y.); (R.S.); (A.H.); (J.S.M.)
- Endocrinology-Reproductive Physiology Program, University of Wisconsin, Madison, WI 53715, USA
| | - Jay S. Mishra
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA; (S.V.D.); (P.Y.); (R.S.); (A.H.); (J.S.M.)
| | - Sathish Kumar
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA; (S.V.D.); (P.Y.); (R.S.); (A.H.); (J.S.M.)
- Endocrinology-Reproductive Physiology Program, University of Wisconsin, Madison, WI 53715, USA
- Department of Obstetrics and Gynecology, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53792, USA;
| |
Collapse
|
2
|
Fouda AY, Ahmed HA, Pillai B, Kozak A, Hardigan T, Ergul A, Fagan SC, Ishrat T. Contralesional angiotensin type 2 receptor activation contributes to recovery in experimental stroke. Neurochem Int 2022; 158:105375. [PMID: 35688299 PMCID: PMC9719365 DOI: 10.1016/j.neuint.2022.105375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 05/27/2022] [Accepted: 05/30/2022] [Indexed: 01/16/2023]
Abstract
We and others have previously shown that angiotensin II receptor type 2 receptor (AT2R) is upregulated in the contralesional hemisphere after stroke in normoglycemic Wistar rats. In this study, we examined the expression of AT2R in type 2 diabetic Goto-Kakizaki (GK) rats and control Wistars after stroke. We also tested the contribution of the contralesional AT2R in recovery after stroke through a specific knockdown of the AT2R in this hemisphere only. Two experiments were conducted. In the first experiment, GK rats were subjected to middle cerebral artery occlusion (MCAO) and treated with the angiotensin II receptor type 1 receptor (AT1R) blocker candesartan or saline at reperfusion. Stroke outcomes, as well as AT2R expression, were examined and compared to control Wistars at 24 h. In the second experiment, localized AT2R knockdown was achieved through intrastriatal injection of short hairpin RNA (shRNA) lentiviral particles or non-targeting control into the left-brain hemisphere of Wistar rats. After 14 days, rats were subjected to right MCAO and treated with the AT2R agonist, Compound 21 (C21), or saline for 7 days. Behavioral outcomes were assessed for up to 10 days. In the first experiment, stroke reduced the expression of AT2R in GK rats. Candesartan treatment failed to improve the neurobehavioral outcomes, preserve vascular integrity or reduce oxidative/nitrative stress or apoptotic markers at 24 h post stroke in these animals. In the second experiment, contralesional AT2R knockdown reduced the C21-mediated functional recovery after stroke. In conclusion, contralesional AT2R upregulation after stroke is blunted in diabetic rats which show reduced sensitivity to post-stroke candesartan treatment. Contralesional AT2R could be involved in C21-mediated functional recovery after stroke.
Collapse
Affiliation(s)
- Abdelrahman Y. Fouda
- University of Arkansas for Medical Sciences, Little Rock, AR, USA,Department of Clinical Pharmacy, Faculty of Pharmacy, Cairo University, Cairo, Egypt,Corresponding author. University of Arkansas for Medical Sciences, Department of Pharmacology and Toxicology, Little Rock, AR, USA. (A.Y. Fouda)
| | - Heba A. Ahmed
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Bindu Pillai
- Charlie Norwood VA Medical Center, Augusta, GA, USA,Center for Pharmacy and Experimental Therapeutics, University of Georgia, College of Pharmacy, Augusta, GA, USA
| | - Anna Kozak
- Charlie Norwood VA Medical Center, Augusta, GA, USA,Center for Pharmacy and Experimental Therapeutics, University of Georgia, College of Pharmacy, Augusta, GA, USA
| | - Trevor Hardigan
- Department of Neurosurgery, Icahn School of Medicine at Mount Sinai Hospital, New York, NY, USA
| | - Adviye Ergul
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, USA,Ralph H. Jackson VA Medical Center, Charleston, SC, USA
| | - Susan C. Fagan
- Charlie Norwood VA Medical Center, Augusta, GA, USA,Center for Pharmacy and Experimental Therapeutics, University of Georgia, College of Pharmacy, Augusta, GA, USA
| | - Tauheed Ishrat
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA,Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN, USA,Corresponding author. University of Tennessee Health Science Center, College of Medicine, Department of Anatomy and Neurobiology, 875 Monroe Avenue, Wittenborg Bldg, Room-231, Memphis, TN, 38163, USA. (T. Ishrat)
| |
Collapse
|
3
|
Volpe M, Battistoni A, Mancia G. Angiotensin II-Linked Hypothesis to Understand the Advantage of the Coevolution of Hypertension and Malaria: "Sympathy for the Devil". Circ Res 2016; 119:1046-1048. [PMID: 27789579 DOI: 10.1161/circresaha.116.309855] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Massimo Volpe
- From the Department of Clinical and Molecular Medicine, School of Medicine and Psychology, Sant'Andrea Hospital, Sapienza University of Rome, Italy (M.V., A.B.); IRCCS Neuromed, Pozzilli, Italy (M.V.); and University of Milano-Bicocca and the Istituto Clinico Universitario Policlinico di Monza,Verano Brianza Milan, Italy (G.M.).
| | - Allegra Battistoni
- From the Department of Clinical and Molecular Medicine, School of Medicine and Psychology, Sant'Andrea Hospital, Sapienza University of Rome, Italy (M.V., A.B.); IRCCS Neuromed, Pozzilli, Italy (M.V.); and University of Milano-Bicocca and the Istituto Clinico Universitario Policlinico di Monza,Verano Brianza Milan, Italy (G.M.)
| | - Giuseppe Mancia
- From the Department of Clinical and Molecular Medicine, School of Medicine and Psychology, Sant'Andrea Hospital, Sapienza University of Rome, Italy (M.V., A.B.); IRCCS Neuromed, Pozzilli, Italy (M.V.); and University of Milano-Bicocca and the Istituto Clinico Universitario Policlinico di Monza,Verano Brianza Milan, Italy (G.M.).
| |
Collapse
|
4
|
Bundalo MM, Zivkovic MD, Romic SD, Tepavcevic SN, Koricanac GB, Djuric TM, Stankovic AD. Fructose-rich diet induces gender-specific changes in expression of the renin-angiotensin system in rat heart and upregulates the ACE/AT1R axis in the male rat aorta. J Renin Angiotensin Aldosterone Syst 2016; 17:1470320316642915. [PMID: 27121972 PMCID: PMC5843877 DOI: 10.1177/1470320316642915] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 02/22/2016] [Indexed: 01/14/2023] Open
Abstract
Introduction: The cardiovascular renin–angiotensin system (RAS) could be affected by gender and dietary regime. We hypothesized that male rats will be more susceptible to activation of RAS in the heart and aorta, as a response to a fructose-rich diet (FRD). Materials and methods: Both male and female Wistar rats were given a 10% (w/v) fructose solution for 9 weeks. We measured the biochemical parameters, blood pressure (BP) and heart rate. We used Western blot and real-time polymerase chain reaction (PCR) to quantify protein and gene expression. Results: In the male rats, the FRD elevated BP and expression of cardiac angiotensin-converting enzyme (ACE), while the expression of angiotensin-converting enzyme 2 (ACE2) and angiotensin II Type 2 receptor (AT2R) were significantly decreased. In female rats, there were no changes in cardiac RAS expression due to FRD. Furthermore, the ACE/AT1R axis was overexpressed in the FRD male rats’ aortae, while only AT1R was upregulated in the FRD female rats’ aortae. ACE2 expression remained unchanged in the aortae of both genders receiving the FRD. Conclusions: The FRD induced gender-specific changes in the expression of the RAS in the heart and aortae of male rats. Further investigations are required in order to get a comprehensive understanding of the underlying mechanisms of gender-specific fructose-induced cardiovascular pathologies.
Collapse
Affiliation(s)
- Maja M Bundalo
- Laboratory for Radiobiology and Molecular Genetics, Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Maja D Zivkovic
- Laboratory for Radiobiology and Molecular Genetics, Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Snjezana Dj Romic
- Laboratory for Molecular Biology and Endocrinology, Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Snezana N Tepavcevic
- Laboratory for Molecular Biology and Endocrinology, Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Goran B Koricanac
- Laboratory for Molecular Biology and Endocrinology, Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Tamara M Djuric
- Laboratory for Radiobiology and Molecular Genetics, Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| | - Aleksandra D Stankovic
- Laboratory for Radiobiology and Molecular Genetics, Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia
| |
Collapse
|
5
|
Babu CS, Kalaivani P, Ranju V, Sathiya S, Anbarasi C, Mahadevan MV, Vijayakumar H, Sunil AG, Thanikachalam S. Venthamarai chooranam, a polyherbal Siddha medicine, alleviates hypertension via AT₁R and eNOS signaling pathway in 2K1C hypertensive rats. Exp Biol Med (Maywood) 2015; 239:758-69. [PMID: 24719376 DOI: 10.1177/1535370214525317] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The present study was aimed to scientifically demonstrate the anti-hypertensive action of Venthamarai chooranam (VMC) in renal hypertensive rats. Two Kidney One Clip (2K1C) Goldblatt model was adopted to induce hypertension in rats. Male Sprague Dawley rats (270-320 g) were randomized into sham (n = 6), vehicle-treated 2K1C (n = 9) and VMC-treated 2K1C (400 mg/kg, p.o; n = 8) and monitored for nine weeks. Systolic blood pressure (SBP), plasma nitrate/nitrite, carotid endothelial nitric oxide synthetase (eNOS), renal angiotensin type 1 receptor (AT₁R), angiotensin type 2 receptor (AT₂R), TNFα, IL-6, thioredoxin 1 (TRX1), and thioredoxin reductase 1 (TRXR1) mRNA expressions were studied. VMC upregulated eNOS expression which in turn improved plasma nitric oxide and decreased SBP in hypertensive rats. It down-regulated AT₁R and simultaneously upregulated AT₂R expression in comparison to vehicle-treated 2K1C rats. Further, renal TNFα and IL-6 expressions were down-regulated while TRX1 and TRXR1 were upregulated by VMC. VMC potentially interacts with renin-angiotensin components and endothelial functions, and thereby exerts its antihypertensive action. This is the first study to demonstrate the mechanism of anti-hypertensive action of VMC in an animal model of renovascular hypertension.
Collapse
MESH Headings
- Animals
- Blood Pressure/drug effects
- Disease Models, Animal
- Gene Expression Regulation/drug effects
- Hypertension, Renovascular/drug therapy
- Hypertension, Renovascular/metabolism
- Hypertension, Renovascular/pathology
- Interleukin-6/biosynthesis
- Male
- Medicine, Ayurvedic
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/pathology
- Nitric Oxide Synthase Type III/metabolism
- Plant Preparations/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/metabolism
- Signal Transduction/drug effects
- Thioredoxins/biosynthesis
- Tumor Necrosis Factor-alpha/biosynthesis
Collapse
|
6
|
Kim HY, Cha HJ, Choi JH, Kang YJ, Park SY, Kim HS. CCL5 Inhibits Elevation of Blood Pressure and Expression of Hypertensive Mediators in Developing Hypertension State Spontaneously Hypertensive Rats. ACTA ACUST UNITED AC 2015. [DOI: 10.4167/jbv.2015.45.2.138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Hye Young Kim
- Department of Microbiology, College of Medicine, Yeungnam University, Daegu, Korea
| | - Hye Ju Cha
- Department of Microbiology, College of Medicine, Yeungnam University, Daegu, Korea
| | - Jin Hee Choi
- Department of Microbiology, College of Medicine, Yeungnam University, Daegu, Korea
| | - Young Jin Kang
- Department of Pharmacology, College of Medicine, Yeungnam University, Daegu, Korea
| | - So Young Park
- Department of Physiology, College of Medicine, Yeungnam University, Daegu, Korea
| | - Hee Sun Kim
- Department of Microbiology, College of Medicine, Yeungnam University, Daegu, Korea
| |
Collapse
|
7
|
Alhusban A, Kozak A, Ergul A, Fagan SC. AT1 receptor antagonism is proangiogenic in the brain: BDNF a novel mediator. J Pharmacol Exp Ther 2012; 344:348-59. [PMID: 23211364 DOI: 10.1124/jpet.112.197483] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Candesartan is an angiotensin II type 1 receptor blocker (ARB) that has been to shown to limit ischemic stroke and improve stroke outcome. In experimental stroke, candesartan induces a proangiogenic effect that is partly attributable to vascular endothelial growth factor. Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family that has been reported to have angiogenic effects and play an important role in recovery after stroke. The purpose of this investigation was to determine the role of BDNF in the proangiogenic effect of candesartan in the brain under hypertensive conditions. Accordingly, spontaneously hypertensive rats were treated with candesartan, and brain tissue samples were collected for quantification of BDNF expression. In addition, human cerebromicrovascular endothelial cells were treated with either low-dose (1 ƒM) or high-dose (1 µM) angiotensin II alone or in combination with candesartan (0.16 µM) to assess the effect of candesartan treatment and BDNF involvement in the behavior of endothelial cells. Candesartan significantly increased the expression of BDNF in the SHR (P < 0.05). In addition, candesartan reversed the antiangiogenic effect of the 1-µM dose of AngII (P = 0.0001). The observed effects of candesartan were ablated by neutralizing the effects of BDNF. Treatment with the AT2 antagonist PD-123319 significantly reduced tube-like formation in endothelial cells. AT2 stimulation induced the BDNF expression and migration (P < 0.05). In conclusion, candesartan exerts a proangiogenic effect on brain microvascular endothelial cells treated with angiotensin II. This response is attributable to increased BDNF expression and is mediated through stimulation of the AT2 receptor.
Collapse
Affiliation(s)
- Ahmed Alhusban
- Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia and Charlie Norwood VA Medical Center, Augusta, GA, USA
| | | | | | | |
Collapse
|
8
|
Gao J, Chao J, Parbhu KJK, Yu L, Xiao L, Gao F, Gao L. Ontogeny of angiotensin type 2 and type 1 receptor expression in mice. J Renin Angiotensin Aldosterone Syst 2012; 13:341-52. [PMID: 22526820 DOI: 10.1177/1470320312443720] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
In the current experiment, we determined angiotensin type 2 receptor (AT2R) and angiotensin type 1 receptor (AT1R) protein expression by western blot analysis in developing normal mice. The results indicate that: (1) in all detected brain regions and in the spinal cord, adult mice exhibited significantly higher AT2R expression and lower AT1R expression in total protein extracts compared to fetuses and neonates; (2) other major organs, including heart, lung, liver and kidney, exhibited the same expression pattern as the brain and spinal cord; (3) reciprocal changes in AT2R and AT1R expression were found in the total protein extracts from the brainstems of mice from one-day prenatal to six weeks of age, and there was a negative correlation between AT2R and AT1R protein expression; (4) in both membrane and cytosolic fractions from the brainstem, adult mice exhibited higher AT2R and lower AT1R expression than did fetuses and neonates; and (5) in the brainstem, there were no significant differences in AT2R and AT1R messenger RNA (mRNA) levels among fetal, neonatal and adult mice. The above results reconfirmed our previous finding in rats that adult animals have higher AT2R and lower AT1R expression compared to fetuses and neonates. These data imply an involvement of AT1R in fetal development and of AT2R in adult function.
Collapse
Affiliation(s)
- Juan Gao
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, USA
| | | | | | | | | | | | | |
Collapse
|
9
|
Savoia C, Volpe M. Angiotensin receptor modulation and cardiovascular remodeling. J Renin Angiotensin Aldosterone Syst 2011; 12:381-4. [PMID: 21880671 DOI: 10.1177/1470320311417750] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Carmine Savoia
- Clinical and Molecular Medicine Department, Cardiology Unit, Sant'Andrea Hospital, Sapienza University of Rome, Rome, Italy.
| | | |
Collapse
|
10
|
Li Y, Madiraju P, Anand-Srivastava MB. Knockdown of natriuretic peptide receptor-A enhances receptor C expression and signalling in vascular smooth muscle cells. Cardiovasc Res 2011; 93:350-9. [PMID: 22131352 DOI: 10.1093/cvr/cvr319] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIMS Natriuretic peptide receptor-A (NPR-A) knockout mice exhibited an increased blood pressure that may also be attributed to the up-regulation of NPR-C and associated signalling; however, the interaction between the two receptors has not been investigated. In the present study, we investigated the effect of knockdown of NPR-A using NPR-A antisense (AS) on the expression of NPR-C and adenylyl cyclase (AC) signalling in A10 vascular smooth muscle cells (VSMC). METHODS AND RESULTS The receptor and G protein expression was determined by western blotting, and AC activity was determined by measuring [(32)P]cAMP formation from [α-(32)P]ATP. Treatment of A10 VSMC with NPR-A AS decreased NPR-A and enhanced NPR-C expression without altering the levels of angiotensin II AT1 and muscarinic M2 receptors. In addition, siRNA-NPR-A also resulted in the up-regulation of NPR-C. The re-expression of NPR-A in AS-treated cells reversed the enhanced expression of NPR-C to control levels. In addition, NPR-C-, AT1, and M2 receptor-mediated inhibition of AC and Giα protein expression was enhanced in AS-treated cells, whereas NPR-A-mediated cyclic GMP (cGMP) formation and Gsα-mediated stimulation of AC were significantly reduced. Pertussis toxin treatment attenuated the AS-induced enhanced inhibition of AC to control levels. Furthermore, the enhanced levels of NPR-C and Giα proteins were reversed to control levels by 8-bromo-cGMP (8Br-cGMP) and PD98059, an MEK inhibitor. In addition, 8Br-cGMP also attenuated AS-induced enhanced ERK1/2 phosphorylation to control levels. CONCLUSION These results demonstrate that knockdown of NPR-A up-regulates the expression of NPR-C, Giα proteins, and NPR-C-linked AC signalling and suggests a cross-talk between NPR-A and NPR-C.
Collapse
Affiliation(s)
- Yuan Li
- Department of Physiology, Faculty of Medicine, University of Montreal, C.P. 6128, Succ. Centre-ville, Montreal, QC, Canada H3C 3J7
| | | | | |
Collapse
|
11
|
Abstract
Hypertension is associated with vascular changes characterised by remodelling, endothelial dysfunction and hyperreactivity. Cellular processes underlying these perturbations include altered vascular smooth muscle cell growth and apoptosis, fibrosis, hypercontractility and calcification. Inflammation, associated with macrophage infiltration and increased expression of redox-sensitive pro-inflammatory genes, also contributes to vascular remodelling. Many of these features occur with ageing, and the vascular phenotype in hypertension is considered a phenomenon of ‘premature vascular ageing’. Among the many factors involved in the hypertensive vascular phenotype, angiotensin II (Ang II) is especially important. Ang II, previously thought to be the sole effector of the renin–angiotensin system (RAS), is converted to smaller peptides [Ang III, Ang IV, Ang-(1-7)] that are biologically active in the vascular system. Another new component of the RAS is the (pro)renin receptor, which signals through Ang-II-independent mechanisms and might influence vascular function. Ang II mediates effects through complex signalling pathways on binding to its G-protein-coupled receptors (GPCRs) AT1R and AT2R. These receptors are regulated by the GPCR-interacting proteins ATRAP, ARAP1 and ATIP. AT1R activation induces effects through the phospholipase C pathway, mitogen-activated protein kinases, tyrosine kinases/phosphatases, RhoA/Rhokinase and NAD(P)H-oxidase-derived reactive oxygen species. Here we focus on recent developments and new research trends related to Ang II and the RAS and involvement in the hypertensive vascular phenotype.
Collapse
|
12
|
|
13
|
Abadir PM, Walston JD, Carey RM, Siragy HM. Angiotensin II Type-2 receptors modulate inflammation through signal transducer and activator of transcription proteins 3 phosphorylation and TNFα production. J Interferon Cytokine Res 2011; 31:471-4. [PMID: 21288138 DOI: 10.1089/jir.2010.0043] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Angiotensin subtype-1 receptor (AT(1)R) influences inflammatory processes through enhancing signal transducer and activator of transcription proteins 3 (STAT3) signal transduction, resulting in increased tumor necrosis factor-α (TNF-α) production. Although angiotensin subtype-2 receptor (AT(2)R), in general, antagonizes AT(1)R-stimulated activity, it is not known if AT(2)R has any anti-inflammatory effects. In this study, we tested the hypothesis that AT(2)R activation plays an anti-inflammatory role by reducing STAT3 phosphorylation and TNF-α production. Changes in AT(2)R expression, TNF-α production, and STAT3 phosphorylation were quantified by Western blotting, Bio-Plex cytokine, and phosphoprotein cellular signaling assays in PC12W cells that express AT(2)R but not AT(1)R, in response to the AT(2)R agonist, CGP-42112 (CGP, 100 nm), or AT(2)R antagonist PD-123319 (PD, 1 μm). A 100% increase in AT(2)R expression in response to stimulation with its agonist CGP was observed. Further, AT(2)R activation reduced TNF-α production by 39% and STAT3 phosphorylation by 83%. In contrast, PD decreased AT(2)R expression by 76%, increased TNF-α production by 84%, and increased STAT3 phosphorylation by 67%. These findings suggest that increased AT(2)R expression may play a role in the observed decrease in inflammatory pathway activation through decreased TNF-α production and STAT3 signaling. Restoration of AT(2)R expression and/or its activation constitute a potentially novel therapeutic target for the management of inflammatory processes.
Collapse
Affiliation(s)
- Peter M Abadir
- Division of Geriatric Medicine and Gerontology, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | | | | | | |
Collapse
|
14
|
Kim HY, Choi JH, Kang YJ, Park SY, Choi HC, Kim HS. Reparixin, an Inhibitor of CXCR1 and CXCR2 Receptor Activation, Attenuates Blood Pressure and Hypertension-Related Mediators Expression in Spontaneously Hypertensive Rats. Biol Pharm Bull 2011; 34:120-7. [DOI: 10.1248/bpb.34.120] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Hye Young Kim
- Department of Microbiology, Aging-associated Vascular Disease Research Center, College of Medicine, Yeungnam University
| | - Jin Hee Choi
- Department of Microbiology, Aging-associated Vascular Disease Research Center, College of Medicine, Yeungnam University
| | - Young Jin Kang
- Department of Pharmacology, Aging-associated Vascular Disease Research Center, College of Medicine, Yeungnam University
| | - So Young Park
- Department of Physiology, Aging-associated Vascular Disease Research Center, College of Medicine, Yeungnam University
| | - Hyoung Chul Choi
- Department of Pharmacology, Aging-associated Vascular Disease Research Center, College of Medicine, Yeungnam University
| | - Hee Sun Kim
- Department of Microbiology, Aging-associated Vascular Disease Research Center, College of Medicine, Yeungnam University
| |
Collapse
|
15
|
Matavelli LC, Huang J, Siragy HM. Angiotensin AT₂ receptor stimulation inhibits early renal inflammation in renovascular hypertension. Hypertension 2010; 57:308-13. [PMID: 21189405 DOI: 10.1161/hypertensionaha.110.164202] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Angiotensin II type 2 receptor (AT₂R) counteracts most effects of angiotensin II type 1 receptor (AT(1)R). We hypothesized that direct AT₂R stimulation reduces renal production of the inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and transforming growth factor-β1 (TGF-β1) and enhances the production of nitric oxide (NO) and cyclic guanosine 3',5'-monophosphate (cGMP) in the clipped kidney of 2-kidney, 1-clip (2K1C) hypertension rat model. We used Sprague-Dawley rats to evaluate changes in renal interstitial fluid recovery levels of TNF-α, IL-6, NO, and cGMP; renal expression of AT₁R, AT₂R, TGF-β1, TNF-α, and IL-6 in sham and 2K1C rats treated for 4 days with vehicle, AT₂R agonist compound 21 (C21), or AT₂R antagonist PD123319 (PD), alone and combined (n=6, each group). Systolic blood pressure increased significantly in 2K1C and was not influenced by any treatment. Clipped kidneys showed significant increases in renal expression of AT₁R, AT₂R, TNF-α, IL-6, TGF-β1 and decreases in NO and cGMP levels. These factors were not influenced by PD treatment. In contrast, C21 caused significant decrease in renal TNF-α, IL-6, TGF-β1 and an increase in NO and cGMP levels. Combined C21 and PD treatment partially reversed the observed C21 effects. Compared to sham, there were no significant changes in TNF-α, IL-6, TGF-β1, NO, or cGMP in the nonclipped kidneys of 2K1C animals. We conclude that direct AT₂R stimulation reduces early renal inflammatory responses and improves production of NO and cGMP in renovascular hypertension independent of blood pressure reduction.
Collapse
Affiliation(s)
- Luis C Matavelli
- Department of Medicine, University of Virginia Health Sciences Center, PO Box 801409, Charlottesville, VA 22908-1409.
| | | | | |
Collapse
|
16
|
Yu L, Zheng M, Wang W, Rozanski GJ, Zucker IH, Gao L. Developmental changes in AT1 and AT2 receptor-protein expression in rats. J Renin Angiotensin Aldosterone Syst 2010; 11:214-21. [PMID: 20807798 DOI: 10.1177/1470320310379065] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
It has long been known that angiotensin type-1 receptors (AT1R) play a critical role in sympathetic regulation, cardiovascular activity, and hormone secretion under physiological and pathological states. On the other hand, the functional significance of angiotensin type-2 receptors (AT2R) is poorly understood. In a recent study we demonstrated that, in rats with chronic heart failure, AT1R protein expression was increased but AT2R expression was decreased in the rostral ventrolateral medulla (RVLM). This imbalance of angiotensin receptors contributed to sympatho-excitation in the heart failure state. In the current experiment, we measured AT1R and AT2R protein expressions in the brainstem, kidney and liver from male foetuses (3 days before birth), male neonates (3 days after birth), male and female adults (8 weeks) and male aged (28 months) rats by Western blot analysis. In the brainstem, we found that the foetuses and neonates exhibited a significantly lower AT2R protein expression compared with adult rats (foetus 0.08 ± 0.01, neonate 0.12 ± 0.01, male adult 0.25 ± 0.01, female adult 0.22 ± 0.02; n = 4 per group, p < 0.001 foetus and neonate compared with male or female adults). In contrast, the foetuses and neonates expressed significantly higher AT1R protein than that of the adults (foetus 0.64 ± 0.09, neonate 0.56 ± 0.01, male adult 0.13 ± 0.02, female adult 0.08 ± 0.02; n = 4 each group, p < 0.001 foetus and neonate compared with male and female adults). In the liver, the AT2R protein was also higher in foetus and neonate, than in adult rats. Interestingly, the foetal liver expressed higher AT1R protein compared with that of the neonate. In the kidney, AT2R expression was significantly increased with age (foetus 0.08 ± 0.01, neonate 0.19 ± 0.02, male adult 0.49 ± 0.04, female adult 0.90 ± 0.10; n = 4 per group, p < 0.01-0.001). AT1R expression, on the other hand, was higher in the foetuses than that in both neonate and male adults. This study provides data contrary to existing dogma that AT2R expression is higher in foetal life and low in adults, suggesting an involvement of a potentially important functional role for AT2R in adult animals and AT1R in foetal development and/or physiology.
Collapse
Affiliation(s)
- Li Yu
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA
| | | | | | | | | | | |
Collapse
|
17
|
Silva KC, Rosales MAB, de Faria JBL, de Faria JML. Reduction of inducible nitric oxide synthase via angiotensin receptor blocker prevents the oxidative retinal damage in diabetic hypertensive rats. Curr Eye Res 2010; 35:519-28. [PMID: 20465447 DOI: 10.3109/02713681003664923] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To investigate if nitric oxide (NO) system contributes to the beneficial effect of angiotensin II type 1 receptor (AT(1)) blocker losartan in the retina of diabetic spontaneously hypertensive rats (SHR). METHODS Diabetic SHR were randomized to receive oral treatment with losartan (DM-SHRLos). After 20 days, the rats were euthanized and the retinas collected. RESULTS Diabetic SHR rats exhibited a significant increase in glial fibrillary acidic protein (GFAP) and decrease in occludin, markers of early diabetic retinopathy (DR). The oxidative status, evaluated by NO end-products (NO(x)(-)) levels along with the antioxidative system superoxide dismutase, revealed an accentuated imbalance in favor to oxidants in DM-SHR leading to a higher tyrosine nitration and DNA damage. The inducible NO synthase (iNOS) was also elevated in DM-SHR rats. The treatment with losartan ameliorated all of the above alterations. CONCLUSIONS Oral treatment with losartan reduces iNOS expression and reestablishes the redox status, thus ameliorating the early markers of DR in a model of diabetes and hypertension.
Collapse
Affiliation(s)
- Kamila C Silva
- Renal Pathophysiology Laboratory, Investigation on Diabetes Complications, Faculty of Medical Sciences (FCM), State University of Campinas (Unicamp), Campinas, São Paulo, Brazil
| | | | | | | |
Collapse
|
18
|
Clapp C, Thebault S, Jeziorski MC, Martínez De La Escalera G. Peptide hormone regulation of angiogenesis. Physiol Rev 2009; 89:1177-215. [PMID: 19789380 DOI: 10.1152/physrev.00024.2009] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
It is now apparent that regulation of blood vessel growth contributes to the classical actions of hormones on development, growth, and reproduction. Endothelial cells are ideally positioned to respond to hormones, which act in concert with locally produced chemical mediators to regulate their growth, motility, function, and survival. Hormones affect angiogenesis either directly through actions on endothelial cells or indirectly by regulating proangiogenic factors like vascular endothelial growth factor. Importantly, the local microenvironment of endothelial cells can determine the outcome of hormone action on angiogenesis. Members of the growth hormone/prolactin/placental lactogen, the renin-angiotensin, and the kallikrein-kinin systems that exert stimulatory effects on angiogenesis can acquire antiangiogenic properties after undergoing proteolytic cleavage. In view of the opposing effects of hormonal fragments and precursor molecules, the regulation of the proteases responsible for specific protein cleavage represents an efficient mechanism for balancing angiogenesis. This review presents an overview of the actions on angiogenesis of the above-mentioned peptide hormonal families and addresses how specific proteolysis alters the final outcome of these actions in the context of health and disease.
Collapse
Affiliation(s)
- Carmen Clapp
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, Mexico.
| | | | | | | |
Collapse
|
19
|
|
20
|
Funke-Kaiser H, Reinemund J, Steckelings UM, Unger T. Adapter proteins and promoter regulation of the angiotensin AT2 receptor — implications for cardiac pathophysiology. J Renin Angiotensin Aldosterone Syst 2009; 11:7-17. [DOI: 10.1177/1470320309343652] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The angiotensin AT 2 receptor (AT2R) represents an important component of the renin-angiotensin system since it is involved in the (patho) physiology of different cardiovascular and neuronal diseases. Furthermore, AT2 receptors can partly mediate beneficial effects of angiotensin AT 1 receptor (AT1R) blockers, and direct pharmacological AT 2 receptor agonism emerges as a novel therapeutic strategy. This review discusses the constitutive and ligand-mediated activity as well as the signal transduction of the AT2 receptor, focusing on adapter proteins which directly bind to this receptor. Direct protein-protein interaction partners of the AT2 receptor described so far include the transcription factor promyelocytic zinc finger protein, AT2 receptor binding protein and the AT1 receptor. In addition, the putative crosstalk of the AT2 receptor with the renin/ prorenin receptor (RER) via the promyelocytic zinc finger protein (PLZF) and the role of oestrogens on the regulation of the AT2 receptor are presented. Conceiving the coupling of the AT2 receptor to different adapter proteins with distinct and partly opposing cellular effects and the implications of its constitutive activity might help to overcome the current controversies on the (patho)physiological role of the AT2 receptor.
Collapse
Affiliation(s)
- Heiko Funke-Kaiser
- Center for Cardiovascular Research (CCR)/Institute of Pharmacology, Charité - Universitätsmedizin Berlin, Berlin, Germany,
| | - Jana Reinemund
- Center for Cardiovascular Research (CCR)/Institute of Pharmacology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Ulrike M Steckelings
- Center for Cardiovascular Research (CCR)/Institute of Pharmacology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Thomas Unger
- Center for Cardiovascular Research (CCR)/Institute of Pharmacology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| |
Collapse
|
21
|
Saito M, Shinohara Y, Sasaki H, Netsu Y, Yoshida M, Nakahata N. Type 1 angiotensin receptor (AT1-R)-mediated decrease in type 2 angiotensin receptor mRNA level is dependent on Gq and extracellular signal-regulated kinase 1//2 in AT1-R-transfected PC12 cells. J Neuroendocrinol 2008; 20:299-308. [PMID: 18208547 DOI: 10.1111/j.1365-2826.2008.01646.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Angiotensin II (Ang II) functions through two major Ang II receptor subtypes, type 1 (AT1-R) and type 2 (AT2-R), both of which are classified to be G protein-coupled receptors. AT2-R is highly expressed at the fetal stage, and in heart remodelling and brain ischaemia; therefore, it is important to clarify the regulatory mechanisms of AT2-R expression. Although AT1-R is generally believed to modulate AT2-R expression in some tissues or cells, the exact mechanism remains to be clarified. In the present study, we examined the effect of AT1-R stimulation on expression of endogenous rat AT2-R (rAT2-R) in AT1-R-transfected PC12 cells. rAT2-R mRNA and protein expression were decreased by Ang II in PC12 cells transfected with rAT1A-R in a time-dependent manner, mediated through a decline in mRNA stability. The C-terminus of G protein-coupled receptor (GPCR) is important for GPCR-mediated signal transduction. Therefore, we used C-terminus-deleted human AT1-R (hAT1-327STOP), which is thought to be a nondesensitised mutant of hAT1-R. As a result, Ang II decreased rAT2-R mRNA expression to a greater extent in cells transfected with hAT1-327STOP than with wild-type hAT1-R. The decrease was completely reversed by AT1-R antagonist candesartan, G(q) inhibitor YM254980, and mitogen-activated protein kinase (MAPK) kinase 1/2 inhibitor U0126, but not by pertussis toxin, which uncouples the receptor with G(i), or p38 MAPK inhibitor SB203580. We suggest, possibly for the first time, that the hAT1-R/G(q)/extracellular signal-regulated kinase 1/2 pathway is involved in the down-regulation of AT2-R using PC12 cells transfected with AT1-R.
Collapse
MESH Headings
- Angiotensin II/pharmacology
- Animals
- Down-Regulation
- GTP-Binding Protein alpha Subunits, Gq-G11/physiology
- Gene Expression Regulation, Neoplastic/drug effects
- Mitogen-Activated Protein Kinase 1/physiology
- Mitogen-Activated Protein Kinase 3/physiology
- PC12 Cells
- Protein Structure, Tertiary/physiology
- RNA Stability/drug effects
- RNA, Messenger/metabolism
- Rats
- Receptor, Angiotensin, Type 1/chemistry
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/physiology
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/metabolism
- Signal Transduction/physiology
- Transfection
Collapse
Affiliation(s)
- M Saito
- Department of Cellular Signalling, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | | | | | | | | | | |
Collapse
|
22
|
Chen Y, Pearlman A, Luo Z, Wilcox CS. Hydrogen peroxide mediates a transient vasorelaxation with tempol during oxidative stress. Am J Physiol Heart Circ Physiol 2007; 293:H2085-92. [PMID: 17644566 DOI: 10.1152/ajpheart.00968.2006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tempol catalyzes the formation of H(2)O(2) from superoxide and relaxes blood vessels. We tested the hypothesis that the generation of H(2)O(2) by tempol in vascular smooth muscle cells during oxidative stress contributes to the vasorelaxation. Tempol and nitroblue tetrazolium (NBT) both metabolize superoxide in vascular smooth muscle cells, but only tempol generates H(2)O(2). Rat pressurized mesenteric arteries were exposed for 20 min to the thromboxane-prostanoid receptor agonist, U-46619, or norepinephrine. During U-46619, tempol caused a transient dilation (22 +/- 2%), whereas NBT was ineffective (2 +/- 1%), and neither dilated vessels constricted with norepinephrine, which does not cause vascular oxidative stress. Neither endothelium removal nor blockade of K(+) channels with 40 mM KCl affected the tempol-induced dilation, but catalase blunted the tempol dilation by 53 +/- 7%. Tempol, but not NBT, increased H(2)O(2) in rat mesenteric vessels detected with dichlorofluorescein. To test physiological relevance in vivo, topical application of tempol caused a transient dilation (184 +/- 20%) of mouse cremaster arterioles exposed to angiotensin II for 30 min, which was not seen with NBT (9 +/- 4%). The vasodilation to tempol was reduced by 68 +/- 6% by catalase. We conclude that the transient relaxation of blood vessels by tempol after prolonged exposure to U-46619 or angiotensin II is mediated in part via production of H(2)O(2) and is largely independent of the endothelium and potassium channels.
Collapse
MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- Angiotensin II/metabolism
- Animals
- Antioxidants/pharmacology
- Catalase/metabolism
- Cells, Cultured
- Cyclic N-Oxides/pharmacology
- Dose-Response Relationship, Drug
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Hydrogen Peroxide/metabolism
- In Vitro Techniques
- Male
- Mesenteric Arteries/drug effects
- Mesenteric Arteries/metabolism
- Mice
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/enzymology
- Myocytes, Smooth Muscle/metabolism
- Nitroblue Tetrazolium/pharmacology
- Norepinephrine/pharmacology
- Oxidative Stress/drug effects
- Potassium Channels/drug effects
- Potassium Channels/metabolism
- Rats
- Rats, Inbred SHR
- Spin Labels
- Superoxide Dismutase/metabolism
- Superoxides/metabolism
- Vasoconstrictor Agents/pharmacology
- Vasodilation/drug effects
- Vasodilator Agents/pharmacology
Collapse
Affiliation(s)
- Yifan Chen
- Cardiovascular Kidney Hypertension Institute, Division of Nephrology & Hypertension, Georgetown Univ., 4000 Reservoir Road, NW, Bldg. D-399, Washington, DC 20057, USA.
| | | | | | | |
Collapse
|
23
|
Dimitropoulou C, Chatterjee A, McCloud L, Yetik-Anacak G, Catravas JD. Angiotensin, bradykinin and the endothelium. Handb Exp Pharmacol 2007:255-94. [PMID: 16999222 DOI: 10.1007/3-540-32967-6_8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Angiotensins and kinins are endogenous peptides with diverse biological actions; as such, they represent current and future targets of therapeutic intervention. The field of angiotensin biology has changed significantly over the last 50 years. Our original understanding of the crucial role of angiotensin II in the regulation of vascular tone and electrolyte homeostasis has been expanded to include the discovery of new angiotensins, their important role in cardiovascular inflammation and the development of clinically useful synthesis inhibitors and receptor antagonists. While less applied progress has been achieved in the kinin field, there are continuous discoveries in bradykinin physiology and in the complexity of kinin interactions with other proteins. The present review focuses on mechanisms and interactions of angiotensins and kinins that deal specifically with vascular endothelium.
Collapse
Affiliation(s)
- C Dimitropoulou
- Vascular Biology Center and Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, GA 30912-2500, USA
| | | | | | | | | |
Collapse
|
24
|
Savoia C, Touyz RM, Volpe M, Schiffrin EL. Angiotensin Type 2 Receptor in Resistance Arteries of Type 2 Diabetic Hypertensive Patients. Hypertension 2007; 49:341-6. [PMID: 17159079 DOI: 10.1161/01.hyp.0000253968.95136.b8] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The role of angiotensin type 2 receptor (AT
2
R) on vascular responses to angiotensin II in humans remains unclear. In this study we explored whether AT
2
R is expressed and functionally active on peripheral resistance arteries of hypertensive diabetic patients treated for 1 year with either the angiotensin receptor blocker valsartan or the β-blocker atenolol. Twenty-six hypertensive type 2 diabetic patients treated with oral hypoglycemic and antihypertensive agents (not receiving angiotensin receptor blockers or β-blockers) were randomly assigned to double-blind treatment for 1 year with valsartan or atenolol once daily added to their previous therapy in a clinical trial that we reported recently and compared with 10 normal subjects. Resistance arteries dissected from gluteal subcutaneous tissues were assessed on a pressurized myograph. Vasomotor response curves to angiotensin II (1 nmol/L to 1 μmol/L) were performed on norepinephrine precontracted vessels in the presence of valsartan (10 μmol/L) with or without the AT
2
R inhibitor PD123319 (1 μmol/L). AT
2
R expression was evaluated by confocal microscopy. After 1 year of treatment, systolic and diastolic blood pressure was controlled and comparable in the valsartan and atenolol groups. Angiotensin II evoked a significant vasodilatory response only on resistance arteries from patients treated with valsartan, effect blocked by PD123319. AT
2
R expression was 4-fold higher in small arteries of valsartan-treated patients. In conclusion, AT
2
Rs are upregulated and contribute to angiotensin II–induced vasodilation in resistance arteries of hypertensive diabetic patients treated with angiotensin type 1 receptor blockers and may mediate, in part, vascular actions of these drugs in high cardiovascular risk patients.
Collapse
Affiliation(s)
- Carmine Savoia
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | | | | | | |
Collapse
|
25
|
Savoia C, Schiffrin EL. Angiotensin Type 2 Receptors in the Cardiovascular System. High Blood Press Cardiovasc Prev 2007. [DOI: 10.2165/00151642-200714020-00002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
|
26
|
Zhou J, Pavel J, Macova M, Yu ZX, Imboden H, Ge L, Nishioku T, Dou J, Delgiacco E, Saavedra JM. AT1 receptor blockade regulates the local angiotensin II system in cerebral microvessels from spontaneously hypertensive rats. Stroke 2006; 37:1271-6. [PMID: 16601219 DOI: 10.1161/01.str.0000217404.64352.d7] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Blockade of angiotensin II AT1 receptors in cerebral microvessels protects against brain ischemia and inflammation. In this study, we tried to clarify the presence and regulation of the local renin-angiotensin system (RAS) in brain microvessels in hypertension. METHODS Spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) controls were treated with an AT1 receptor antagonist (candesartan, 0.3 mg/kg per day) via subcutaneous osmotic minipumps for 4 weeks. The expression and localization of RAS components and the effect of AT1 receptor blockade were assessed by Affymetrix microarray, qRT-PCR, Western blots, immunohistochemistry and immunofluorescence. RESULTS We found transcripts of most of RAS components in our microarray database, and confirmed their expression by qRT-PCR. Angiotensinogen (Aogen), angiotensin-converting enzyme (ACE) and AT1 receptors were localized to the endothelium. There was no evidence of AT2 receptor localization in the microvascular endothelium. In SHR, (pro)renin receptor mRNA and AT1 receptor mRNA and protein expression were higher, whereas Aogen, ACE mRNA and AT2 receptor mRNA and protein expression were lower than in WKY rats. Candesartan treatment increased Aogen, ACE and AT2 receptor in SHR, and increased ACE and decreased Aogen in WKY rats, without affecting the (pro)renin and AT1 receptors. CONCLUSIONS Increased (pro)renin and AT1 receptor expression in SHR substantiates the importance of the local RAS overdrive in the cerebrovascular pathophysiology in hypertension. AT1 receptor blockade and increased AT2 receptor stimulation after administration of candesartan may contribute to the protection against brain ischemia and inflammation.
Collapse
Affiliation(s)
- Jin Zhou
- Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Chrysant SG, Chrysant GS. The pleiotropic effects of angiotensin receptor blockers. J Clin Hypertens (Greenwich) 2006; 8:261-8. [PMID: 16596029 PMCID: PMC8109722 DOI: 10.1111/j.1524-6175.2005.05264.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Revised: 11/29/2005] [Accepted: 12/12/2005] [Indexed: 12/13/2022]
Abstract
The angiotensin receptor blockers (ARBs) are very effective and safe antihypertensive drugs. They exert their antihypertensive effect through blockage of the angiotensin II, type 1 receptor and quite possibly through stimulation by angiotensin II of the unoccupied type 2 receptor. Besides hypertension, the ARBs have been found recently to be of value in the treatment of heart failure and diabetic nephropathy. In addition, ARBs have emerged lately as being very effective and perhaps superior to other antihypertensive drugs in the prevention of de novo or recurrent strokes. Other actions that may account for their stroke-protective effects include their antiatherogenic, antidiabetic, antiplatelet aggregating, hypouricemic, and atrial antifibrillatory actions. All these actions make the ARBs a true pleiotropic class of drugs. Each of the foregoing effects will be discussed briefly in this concise review.
Collapse
Affiliation(s)
- Steven G Chrysant
- Oklahoma Cardiovascular and Hypertension Center and the University of Oklahoma School of Medicine, 5850 West Wilshire Boulevard, Oklahoma City, OK 73132-4904, USA.
| | | |
Collapse
|
28
|
de P Rodrigues SF, dos Santos RA, Silva-Antonialli MM, Scavone C, Nigro D, Carvalho MHC, de Cássia Tostes R, Fortes ZB. Differential effect of losartan in female and male spontaneously hypertensive rats. Life Sci 2006; 78:2280-5. [PMID: 16337658 DOI: 10.1016/j.lfs.2005.09.049] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2005] [Accepted: 09/19/2005] [Indexed: 11/22/2022]
Abstract
We demonstrated that the decreased response to acetylcholine observed in aorta of male and female spontaneously hypertensive rats is corrected after sustained (15 days) reduction of blood pressure levels by losartan. In order to verify if the same occurs in resistance vessels, vascular diameter changes induced by topical application of acetylcholine and bradykinin (endothelium-dependent vasodilators) and sodium nitroprusside (endothelium-independent vasodilator) to mesenteric arterioles studied in vivo, in situ were determined in rats treated with losartan for 24 h (acute) or 15 days (chronic). Rats that presented similar reduction (in %) of the blood pressure levels after losartan treatment were chosen. Sodium nitroprusside induced similar responses in losartan-treated and untreated male or female SHR. Whereas in female SHR, losartan corrected the diminished arteriolar response to endothelium-dependent vasodilators after acute and chronic treatment, in male SHR this correction only occurred after chronic treatment. Thus, losartan corrected the endothelial dysfunction more easily in female than in male SHR and independently of the normalization or the magnitude of the reduction of the blood pressure levels. In an attempt to explain the difference, we evaluated the losartan effect on nitric-oxide synthase (NOS) activity and angiotensin II AT1 and AT2 receptor gene expression in these animals. In male and female SHR, NOS activity and AT1 receptor expression were not altered by acute or chronic treatment. On the other hand, AT2 receptor expression was augmented only in female SHR by these treatments. Therefore, augmented AT2 receptor expression, but not alteration of NOS activity or AT1 receptor expression, might explain the difference observed.
Collapse
Affiliation(s)
- Stephen F de P Rodrigues
- Laboratory of Hypertension, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, Brazil
| | | | | | | | | | | | | | | |
Collapse
|
29
|
Savoia C, Tabet F, Yao G, Schiffrin EL, Touyz RM. Negative regulation of RhoA/Rho kinase by angiotensin II type 2 receptor in vascular smooth muscle cells: role in angiotensin II-induced vasodilation in stroke-prone spontaneously hypertensive rats. J Hypertens 2005; 23:1037-45. [PMID: 15834290 DOI: 10.1097/01.hjh.0000166845.49850.39] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To test whether angiotensin II (Ang II) through the Ang II type 2 receptor (AT2R), downregulates RhoA/Rho kinase, which plays a role in AT1 receptor (AT1R)-mediated function. METHODS In vitro studies were performed in A10 vascular smooth muscle cells (VSMC) and in vivo studies in mesenteric arteries from Wistar-Kyoto (WKY) and stroke-prone spontaneously hypertensive (SHRSP) rats. VSMC were stimulated with Ang II (10 mol/l), CGP42112A (10 mol/l, a selective AT2R agonist) +/- valsartan (10 mol/l, an AT1R antagonist), or the Rho kinase inhibitor fasudil (10 mol/l). AT1R and AT2R expression and myosin light chain (MLC) phosphorylation were determined by immunoblotting. RhoA activity was assessed by measuring membrane translocation. Functional significance between AT2R, RhoA/Rho kinase and vasodilation was assessed in arteries from valsartan-treated (30 mg/kg per day, 14 days) WKY and SHRSP rats. Vasodilatory responses to Ang II (10-10 mol/l) were performed in norepinephrine pre-contracted vessels +/- valsartan(10 mol/l), PD123319 (10 mol/l, an AT2R antagonist) or fasudil (10 mol/l). RESULTS A10 VSMC expressed AT1R and AT2R. In valsartan-treated cells, Ang II-induced RhoA translocation was reduced versus controls (42 +/- 6%, P < 0.05). Similar responses were obtained with CGP42112A (45 +/- 6%, P < 0.05). This was associated with decreased MLC activation. Fasudil abrogated Ang II- and CGP42112A-mediated effects. Ang II evoked a significant vasodilatory response only in valsartan-treated SHRSP (max dilation 40 +/- 7%). PD123319 blocked these effects. Fasudil increased AngII-induced relaxation in SHRSP vessels. AT2R expression was increased by valsartan (two- to three-fold) in SHRSP arteries. RhoA translocation was increased two-fold in untreated SHRSP (P < 0.05) and was reduced by valsartan (P < 0.05). These changes were associated with decreased MLC phosphorylation. CONCLUSIONS Ang II/AT2R negatively regulates vascular RhoA/Rho kinase/MLC phosphorylation. These processes may play a role in Ang II-mediated vasodilation in conditions associated with vascular AT2R upregulation, such as in SHRSP chronically treated with AT1R blockers, which may contribute to blood pressure lowering by these antihypertensive agents.
Collapse
Affiliation(s)
- Carmine Savoia
- CIHR Multidisciplinary Research Group on Hypertension, Clinical Research Institute of Montreal, University of Montreal, Quebec, Canada
| | | | | | | | | |
Collapse
|
30
|
Chrysant SG. Possible pathophysiologic mechanisms supporting the superior stroke protection of angiotensin receptor blockers compared to angiotensin-converting enzyme inhibitors: clinical and experimental evidence. J Hum Hypertens 2005; 19:923-31. [PMID: 16049519 DOI: 10.1038/sj.jhh.1001916] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Stroke is a major cause of death and disability and its incidence increases linearly with age and the level of systolic and diastolic blood pressure. Stroke, besides being a cause of long-term disability for the affected person, also imposes a significant burden on society and healthcare costs. Although good blood pressure control is very critical for stroke prevention, angiotensin receptor blockers (ARBs) may be superior to angiotensin-converting enzyme inhibitors (ACEIs) for the same degree of blood pressure control. This hypothesis has clinical and experimental support. ARBs prevent stroke incidence by blocking the angiotensin II (AII), AT1 receptors preventing brain ischaemia and allowing AII to stimulate the unoccupied AT2 receptors, which improve brain ischaemia. ACEIs, by reducing AII generation, are less effective in preventing stroke. This hypothesis provides evidence that AII plays an important role in the prevention of stroke. Certain ARBs like losartan, and telmisartan, irbesartan and candesartan possess additional properties which may play a role in stroke prevention, which is independent of AII. These include antiplatelet aggregating, hypouricemic, antidiabetic and atrial antifibrillatory effects. However, the most critical factor in stroke prevention is good blood pressure control irrespective of drug used.
Collapse
Affiliation(s)
- S G Chrysant
- Oklahoma Cardiovascular and Hypertension Center, Oklahoma City, OK 73132-4904, USA.
| |
Collapse
|
31
|
Abstract
Male Wistar rats were treated with an angiotensin AT1 receptor antagonist, candesartan cilexetil (TCV-116, 1 mg/kg/day) over a 4-week period. Systolic blood pressure was significantly reduced by 14% after 1 week and remained stable for the next 3 weeks compared with controls. Up-regulation of AT2, but not AT1, receptor gene expression by 3.4-fold and 5.0-fold was observed 1 and 4 weeks after treatment. Middle cerebral artery occlusion caused significantly reduced infarct volumes in TCV-116-treated rats, by about 30% when compared with control rats. Neurological scores were also improved in treated rats. These results suggest that the neuroprotective effects of TCV-116 may be mediated through AT1 receptor antagonism and AT2 receptor up-regulation.
Collapse
MESH Headings
- Analysis of Variance
- Angiotensin II Type 1 Receptor Blockers/therapeutic use
- Animals
- Benzimidazoles/therapeutic use
- Biphenyl Compounds/therapeutic use
- Blood Pressure/drug effects
- Body Weight/drug effects
- Brain Infarction/etiology
- Brain Infarction/prevention & control
- Functional Laterality/physiology
- Gene Expression/drug effects
- Heart Rate/drug effects
- Infarction, Middle Cerebral Artery/complications
- Infarction, Middle Cerebral Artery/drug therapy
- Male
- Neurologic Examination/methods
- RNA, Messenger/metabolism
- Rats
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/metabolism
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Tetrazoles/therapeutic use
- Tetrazolium Salts
- Time Factors
Collapse
Affiliation(s)
- Qing Lu
- Department of Pharmacology, Faculty of Medicine, National University of Singapore, 18 Medical Drive, Singapore 117597
| | | | | |
Collapse
|
32
|
Abstract
The renin-angiotensin system (RAS) is a major physiological regulator of vascular tone and is implicated in cardiovascular pathophysiology. More recently, basic research has however continuously extended our understanding of the complexicity of the systemic and tissular RASs. The peptid hormone, angiotensin II, acts primarily via type I (AT1) and type II (AT2) angiotensin receptors. Most, if not all, of the peripheral and central actions of angiotensin II, including vasoconstriction, renal salt and water retention, facilitation of sympathetic transmission, modification of vascular and cardiac structure, oxydative stress stimulation and proinflammatory action were all thought to be mediated by the angiotensin type 1 receptor, AT1. Angiotensin II/III exerts actions through the AT2 receptor, which are directly opposed to those mediated by the AT1 receptor. Most notably, proteolytic fragments of angiotensin II also have biological activity via ther own receptors: angiotensin-(1-7)/AT1-7 and angiotensin IV/AT4. They are vasodilators in many arterial beds. The identification of these angiotensins opens the way to develop new therapeutics.
Collapse
Affiliation(s)
- N Oudart
- Laboratoire de Pharmacologie, Faculté de Pharmacie, 2, rue du Dr Marcland, F87025 Limoges Cedex
| |
Collapse
|
33
|
Newton CR, Curran B, Victorino GP. Angiotensin II type 1 receptor activation increases microvascular permeability via a calcium dependent process1. J Surg Res 2005; 123:33-9. [PMID: 15652948 DOI: 10.1016/j.jss.2004.07.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2003] [Indexed: 11/29/2022]
Abstract
BACKGROUND Elevated serum angiotensin II (Ang II) has been implicated in the endothelial barrier dysfunction associated with shock. We hypothesized that the increase in microvascular permeability seen with activation of the type 1 (AT1) receptor is a calcium dependent process. MATERIALS AND METHODS Microvascular hydraulic permeability (Lp) was measured in rat mesenteric venules using the Landis micro-occlusion model. A 100 mm KCl (HK) solution was used to negate the electrochemical potential of calcium influx, and measures of Lp were obtained before and after 20 ng/ml Ang II plus HK solution (n = 5). Intracellular calcium dependence on AT1 activation was evaluated two ways: 1) Lp changes were measured in response to 10 microm of the type 1 receptor agonist [SAR] [1]-angiotensin II in HK solution (n = 6), and 2) Lp changes were measured in response to 25 microg/ml of the type 2 (AT2) receptor blocker PD-123319 (PD) plus 20 ng/ml Ang II in HK solution (n = 6). RESULTS As expected, HK perfusion (P < 0.08) and Ang II plus HK solution (P < 0.42) did not affect Lp. Although perfusion of [SAR] [1]-angiotensin II in HK solution (P < 0.001) and PD plus Ang II in HK solution (P < 0.003) both significantly increased Lp, the magnitude of this response was less than that observed with Ang II alone. CONCLUSIONS Abrogation of intracellular calcium influx during AT1 activation blunted the known Ang II induced increase in microvascular permeability. Although the effect observed during AT1 activation was blunted by the HK solution, a significant elevation of Lp was still observed. This suggests that Ang II activation of the AT1 receptor increases microvascular permeability primarily, but not exclusively, via modulation of endothelial intracellular calcium ion levels.
Collapse
Affiliation(s)
- Christopher R Newton
- Department of Surgery, UCSF-East Bay, Alameda County Medical Center, Oakland, California 94602, USA
| | | | | |
Collapse
|
34
|
Siragy HM, Carey RM. The Angiotensin Receptors: AT1 and AT2. Hypertension 2005. [DOI: 10.1016/b978-0-7216-0258-5.50101-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
35
|
Bédard S, Sicotte B, St-Louis J, Brochu M. Modulation of body fluids and angiotensin II receptors in a rat model of intra-uterine growth restriction. J Physiol 2004; 562:937-50. [PMID: 15539403 PMCID: PMC1665548 DOI: 10.1113/jphysiol.2004.064683] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We previously reported that sodium restriction during pregnancy reduces plasma volume expansion and promotes intra-uterine growth restriction (IUGR) in rats while it activates the renin-angiotensin-aldosterone system (RAAS). In the present study, we proceeded to determine whether expression of the two angiotensin II (ANGII) receptor subtypes (AT(1) and AT(2)) change in relation to maternal water-electrolyte homeostasis and fetal growth. To this end, pregnant (gestation day 15) and non-pregnant Sprague-Dawley rats were randomly assigned to two groups fed either normal, or Na(+)-restricted diets for 7 days. At the end of the treatment period, plasma aldosterone and renin activity as well as plasma and urine electrolytes were measured. Determinations for AT(1) and AT(2) mRNA and protein were made by RNase protection assay and photoaffinity labelling, respectively, using a number of tissues implicated in volume regulation and fetal growth. In non-pregnant rats, Na(+) restriction decreases Na(+) excretion without altering plasma volume, plasma Na(+) concentration or the expression of AT(1) and AT(2) mRNA or protein in the tissues examined. In normally fed pregnant rats when compared to non-pregnant controls, AT(1) mRNA increases in the hypothalamus as well as pituitary and declines in uterine arteries, while AT(1) protein decreases in the kidney and AT(2) mRNA declines in the adrenal cortex. In pregnant rats, Na(+) restriction induces a decrease in plasma Na(+), an increase in plasma urea, as well as a decline in renal urea and creatinine clearance rates. Protein levels for both AT(1) and AT(2) in the pituitary and AT(2) mRNA in the adrenal cortex are lower in the Na(+)-restricted pregnant group when compared to normally fed pregnant animals. Na(+) restriction also induces a decrease in AT(1) protein in the placenta. In conclusion, these results suggest that pregnancy may increase sensitivity to Na(+) depletion by the tissue-specific modulation of ANGII receptors. Finally, these receptors may be implicated in the IUGR response to low Na(+).
Collapse
Affiliation(s)
- Sophie Bédard
- Centre de Recherche, Department of Obstetrics-Gynecology, Université de Montréal, Hôpital Sainte-Justine, 3175 Côte Ste-Catherine, Montréal, Québec, Canada H3T 1C5
| | | | | | | |
Collapse
|
36
|
Newton CR, Curran B, Victorino GP. Angiotensin II type 2 receptor effect on microvascular hydraulic permeability. J Surg Res 2004; 120:83-8. [PMID: 15172193 DOI: 10.1016/j.jss.2003.12.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2003] [Indexed: 11/30/2022]
Abstract
BACKGROUND Angiotensin II (Ang II) is a potent vasoconstrictor that modulates microvascular permeability. Angiotensin II type 1 (AT1) and type 2 (AT2) receptors have been described with subsequent development of their respective antagonists. We hypothesized that the AT2 receptor modulates microvascular permeability. MATERIALS AND METHODS Hydraulic permeability (L(p)) was measured in rat mesenteric venules using the Landis micro-occlusion technique. Following baseline L(p) measurements, paired measures of microvessel L(p) were obtained after perfusion with a test solution. The test solutions consisted of the AT2 receptor agonist CGP42112A at 10 microm (n = 6), 100 microm (n = 6), and 200 microm (n = 6), as well as the AT2 receptor antagonist PD-123319 at 3 microm (n = 6), 30 microm (n = 6), 300 microm (n = 6), and 600 microm (n = 6). RESULTS From mean baseline L(p) of 0.99 +/- 0.03, 100 microm CGP42112A decreased L(p) to 0.76 +/- 0.02 (P = 0.005), and 200 microm CGP42112A decreased L(p) to 0.61 +/- 0.02 (P < 0.001). From mean baseline L(p) of 0.90 +/- 0.05, PD-123319 increased L(p) at 30 microm to 1.60 +/- 0.2 (P = 0.003), at 300 microm to 2.28 +/- 0.3 (P = 0.008), and at 600 microm to 4.30 +/- 0.9 (P = 0.03). Units for L(p) are mean +/- SEM x 10(-7) cm s(-1) cmH(2)O(-1). CONCLUSION AT2 activation decreased L(p), while AT2 blockade increased L(p). These changes in L(p) may be explained by (1). a permeability-decreasing effect of the AT2 receptor that is induced by AT2 activation and inhibited by AT2 blockade; and/or (2). a permeability-increasing effect of the AT1 receptor observed during AT2 blockade and selective AT1 activation by endogenous locally released Ang II. These mechanisms would support the theories that the AT1 receptor increases microvascular permeability, while the AT2 receptor decreases microvascular permeability.
Collapse
Affiliation(s)
- Christopher R Newton
- Department of Surgery, UCSF-East Bay, Alameda County Medical Center, Oakland, California 94602, USA
| | | | | |
Collapse
|
37
|
de Godoy MAF, de Oliveira AM, Rattan S. Angiotensin II-Induced Relaxation of Anococcygeus Smooth Muscle via Desensitization of AT1Receptor, and Activation of AT2Receptor Associated with Nitric-Oxide Synthase Pathway. J Pharmacol Exp Ther 2004; 311:394-401. [PMID: 15178697 DOI: 10.1124/jpet.104.069856] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We evaluated the role of receptor desensitization, activation of AT(2) receptors, and enzymatic degradation of angiotensin II (Ang II) by amino/neutral endopeptidases in rat anococcygeus smooth muscle (ASM) relaxation. Ang II (0.3 nM to 10 microM) produced contractions (E(max) = 21.50 +/- 5.73%) followed by passive relaxations (E(max) reduced to 9.08 +/- 2.55%). Contractions were inhibited (E(max) = 13.67 +/- 2.03%) by losartan (0.1 microM; AT(1) antagonist) but not by PD123,319 [S-(+)-1-([4-(dimethylamino)-3-methylphenyl]methyl)-5-(diphenylacetyl)-4,5,6,7-tetrahydro-1H-imidazo(4,5-c)pyridine-6-carboxylic acid] (0.1 microM; AT(2) antagonist). Conversely, the passive relaxation was inhibited (E(max) = 18.00 +/- 3.45%) by PD123,319 but not by losartan. Ang II (0.3 microM to 100 microM) produced initial contractions (E(max) = 11.49 +/- 9.39%) followed by active relaxations [I(max) (maximum inhibition elicited by the agonist) = 47.85 +/- 4.23%] on strips precontracted by bethanechol (100 microM). A second administration of Ang II on the background of bethanechol (1 h later) resulted in stronger relaxations (I(max) = 64.03 +/- 5.47%) without the initial contractions. N(G)-Nitro-l-arginine methyl ester [nitric-oxide synthase (NOS) inhibitor], ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one; guanylate cyclase inhibitor), PD123,319, and tetrodotoxin (neurotoxin) inhibited the relaxations. The presence of AT(1) and AT(2) receptors was confirmed by Western blot. Experiments with amastatin (1 microM) and thiorphan (1 microM), aminopeptidase, and neutral endopeptidase inhibitors, respectively, excluded the involvement of enzymatic degradation in Ang II-induced relaxation of ASM. In conclusion, the rat ASM relaxation by Ang II is the result of active and passive relaxations. The passive relaxation depends on desensitization of excitatory AT(1) receptors, and the active relaxation is mediated by stimulation of AT(2) receptors and activation of the neuronal NOS/soluble guanylate cyclase pathway.
Collapse
MESH Headings
- Adenine/analogs & derivatives
- Adenine/pharmacology
- Angiotensin II/analogs & derivatives
- Angiotensin II/pharmacology
- Animals
- Blotting, Western
- CD13 Antigens
- Drug Interactions
- Glutamyl Aminopeptidase/metabolism
- Imidazoles/pharmacology
- Losartan/pharmacology
- Male
- Muscle Contraction/drug effects
- Muscle Relaxation/drug effects
- Muscle, Smooth/drug effects
- Muscle, Smooth/physiology
- NG-Nitroarginine Methyl Ester/pharmacology
- Nitric Oxide Synthase/metabolism
- Peptide Fragments/pharmacology
- Peptides/pharmacology
- Pyridines/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptor, Angiotensin, Type 1/drug effects
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/metabolism
- Tetrodotoxin/pharmacology
- Thiorphan/pharmacology
Collapse
Affiliation(s)
- Márcio A F de Godoy
- Department of Medicine, Division of Gastroenterology & Hepatology, Jefferson Medical College, Thomas Jefferson University, 1025 Walnut Street, Room # 901 College, Philadelphia, PA 19107, USA
| | | | | |
Collapse
|
38
|
Fournier A, Achard JM, Boutitie F, Mazouz H, Mansour J, Oprisiu R, Fernandez L, Messerli F. Is the angiotensin ii type 2 receptor cerebroprotective? Curr Hypertens Rep 2004; 6:182-9. [PMID: 15128469 DOI: 10.1007/s11906-004-0067-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Most of the deleterious effects of angiotensin II (Ang II) on blood pressure (BP), cardiovascular remodeling, and atherosclerosis are mediated by Ang II type 1 (AT1)-receptor activation. This explains why Ang-II-decreasing or blocking drugs have been successful in decreasing global cardiovascular morbimortality in patients with cardiac complications. However, in primary or secondary stroke prevention trials in patients with low cardiac risk, b-blockers and angiotensin-converting enzyme inhibitors (ACEIs), which decrease Ang II formation, seem to be less protective than thiazides and dihydropyridines, which increase Ang II. When compared with a beta-blocker, an Ang II-increasing AT1-receptor blocker better protects against stroke but not against cardiac events, whereas an ACEI gives the same protection against both cardiac and cerebral events. This dissociation between blood-pressure-independent cardiac and cerebral protection between b-blockers or ACEIs versus AT1-blockers in patients with low cardiac risk can be best explained if, besides the beneficial vascular effect of AT1-receptor blunting, there is evidence of a beneficial effect of non-AT1-receptor activation. In this review, we present experimental evidence for AT2- and AT4-receptor-mediated brain-anti-ischemic mechanisms and propose a direct comparison of AT1-blockers with ACEIs to prove the clinical effectiveness of non-AT1-mediated mechanisms in stroke prevention, particularly in patients with a higher risk for stroke than for cardiac complications.
Collapse
Affiliation(s)
- Albert Fournier
- Service de Néphrologie, CHU SUD, Avenue René Laënnec, 80054 Amiens 1, France.
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Widdop RE, Jones ES, Hannan RE, Gaspari TA. Angiotensin AT2 receptors: cardiovascular hope or hype? Br J Pharmacol 2003; 140:809-24. [PMID: 14530223 PMCID: PMC1574085 DOI: 10.1038/sj.bjp.0705448] [Citation(s) in RCA: 174] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2003] [Revised: 06/30/2003] [Accepted: 07/10/2003] [Indexed: 02/02/2023] Open
Abstract
British Journal of Pharmacology (2003) 140, 809–824. doi:10.1038/sj.bjp.0705448
Collapse
Affiliation(s)
- Robert E Widdop
- Department of Pharmacology, Monash University, Melbourne, Victoria 3800, Australia.
| | | | | | | |
Collapse
|
40
|
Jones A, Dhamrait SS, Payne JR, Hawe E, Li P, Toor IS, Luong L, Wootton PTE, Miller GJ, Humphries SE, Montgomery HE. Genetic variants of angiotensin II receptors and cardiovascular risk in hypertension. Hypertension 2003; 42:500-6. [PMID: 12925562 DOI: 10.1161/01.hyp.0000088853.27673.d0] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Renin-angiotensin systems may mediate cardiovascular disease pathogenesis through a balance of actions of angiotensin II on (potentially proatherogenic) constitutive type 1 (AT1R) and (potentially antiatherogenic) inducible type 2 (AT2R) receptors. We explored such potential roles in a prospective candidate gene association study. Cardiovascular end points (fatal, nonfatal, and silent myocardial infarction and coronary artery bypass surgery/angioplasty) were documented among 2579 healthy UK men (mean age, 56.1+/-3.5 years; median follow-up, 10.1 years) genotyped for the AT1R1166A>C and the X chromosome located AT2R1675A>G and 3123C>A polymorphisms. Baseline characteristics, including blood pressure, were independent of genotype. The AT1R1166CC genotype was associated with relative cardiovascular risk (hazard ratio, 1.65 [1.05 to 2.59]; P=0.03) independent of blood pressure. Systolic blood pressure was associated with risk (P=0.0005), but this association was restricted to AT2R1675A allele carriers (P<0.00001), with G allele carriers protected from the risk associated with blood pressure (P=0.18). Hypertensive carriers with the AT2R1675A/3123A haplotype were at most risk, with 37.5% having an event. This is the first study to demonstrate an association of AT2R genotype with coronary risk, an effect that was confined to hypertensive subjects and supports the concept that the inducible AT2R is protective. Conversely, the AT1R1166CC genotype was associated with cardiovascular risk irrespective of blood pressure. These data are important to our understanding of the divergent role of angiotensin II acting at its receptor subtypes and coronary disease pathogenesis and for the development of future cardiovascular therapies.
Collapse
Affiliation(s)
- Alun Jones
- Centre for Cardiovascular Genetics, Royal Free and University College Medical School, London, UK
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Volpe M, Musumeci B, De Paolis P, Savoia C, Morganti A. Angiotensin II AT2 receptor subtype: an uprising frontier in cardiovascular disease? J Hypertens 2003; 21:1429-43. [PMID: 12872031 DOI: 10.1097/00004872-200308000-00001] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The renin-angiotensin system (RAS) plays a pivotal role in the regulation of fluid, electrolyte balance and blood pressure, and is a modulator of cellular growth and proliferation. Biological actions of RAS are linked to the binding of the effector molecule, angiotensin II (AngII), to specific membrane receptors, mostly the AT1 subtype and, to a lesser extent, other subtypes. Following the identification and characterization of the AT2 subtype receptor, it has been proposed that a complex interaction between AngII and its receptors may play an important role in the effects of RAS. In this paper current information on AngII subtype receptors--their structure, regulation and intracellular signalling--are reviewed, with a particular emphasis on the potential relevance for cardiovascular pathophysiology. In addition, we discuss modulation of expression of the AT2 receptor and its interaction with the AT1 receptor subtype, as well as the potential effects of this receptor on blood pressure regulation. A better understanding of the integrated effects of the AngII subtype receptors may help to elucidate the function of the RAS, as well as their participation in the mechanisms of cardiovascular disease and attendant therapeutic implications.
Collapse
Affiliation(s)
- Massimo Volpe
- Cattedra di Cardiologia, II Facoltà di Medicina, Dipartimento di Medicina Sperimentale e Patologia, Università La Sapienza, Rome, Italy.
| | | | | | | | | |
Collapse
|
42
|
Volpe M, Savoia C, De Paolis P, Ostrowska B, Tarasi D, Rubattu S. The renin-angiotensin system as a risk factor and therapeutic target for cardiovascular and renal disease. J Am Soc Nephrol 2002; 13 Suppl 3:S173-8. [PMID: 12466309 DOI: 10.1097/01.asn.0000032549.36050.78] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The renin-angiotensin system (RAS) plays an important homeostatic role in BP regulation, water and salt balance, and tissue growth control under physiologic conditions. On the other hand, a pivotal involvement of the RAS in the pathophysiology of cardiovascular and renal disease is extensively supported by both basic and clinical evidence. In particular, it is today recognized that angiotensin II (AngII), the biologic effector of the RAS, may prompt a number of relevant structural and functional abnormalities through the activation of a complex of cellular effects mostly mediated via its binding with the AT(1) subtype receptors. The key role of these AngII-linked mechanisms of disease is strongly corroborated by large interventional studies. In fact, pharmacologic interference with RAS activity, by both preventing AngII formation with angiotensin-converting enzyme inhibitors or antagonizing its binding to cell membrane receptors by selective antagonists, is associated with highly beneficial outcomes in major disease conditions (hypertension, diabetes, renal failure, heart failure, myocardial infarction, stroke, and others). This article briefly reviews the current views on the biologic organization of RAS evidence supporting a pathogenic role of the RAS activity in promoting cardiac, vascular, and renal disease, and finally provides the basis for considering inhibition of RAS activity a major target for therapeutic interventions in these conditions.
Collapse
Affiliation(s)
- Massimo Volpe
- Department of Experimental Medicine and Pathology, University of Rome La Sapienza, Italy. volpema@uniroma1@it
| | | | | | | | | | | |
Collapse
|
43
|
Abstract
BACKGROUND Angiotensin II (Ang II) is a potent vasoconstrictor that is released during shock and sepsis. It is known to have activity on vascular endothelial cells. We hypothesized that Ang II plays a role in the modulation of fluid flux across the microvascular endothelium. MATERIALS AND METHODS Hydraulic permeability (L(p)) is a measure of water flow across the endothelial barrier. L(p) was measured in rat mesenteric venules using the modified Landis micro-occlusion technique. To determine the effect of Ang II in basal states, venules were perfused with control Ringer's and measures of L(p) obtained before and after a subsequent perfusion with 20 ng/ml Ang II (n = 5). In additional studies 10 microM ATP was used to activate the endothelium, thereby increasing the L(p) approximately 3-fold. Measures of L(p) were then obtained before and after a subsequent perfusion with 20 ng/ml Ang II (n = 6). RESULTS In the basal state, Ang II significantly increased L(p) from 1.45 +/- 0.29 to 3.45 +/- 0.28 (P = 0.013). Following activation by ATP, Ang II decreased L(p) from 4.51 +/- 0.45 to 3.05 +/- 0.28 (P = 0.02). Units for L(p) are x10(-7) cm s(-1) x cm H(2)O(-1). CONCLUSIONS Ang II increased microvascular permeability under basal conditions while in the activated state it decreased microvascular permeability. In addition to its vasopressor function this differential action of Ang II in modulating fluid flux across the fsendothelium in basal versus activated states may be of benefit under pathophysiological conditions and may be amenable to pharmacologic manipulation.
Collapse
Affiliation(s)
- Gregory P Victorino
- Department of Surgery, University of California, San Francisco--East Bay, Alameda County Medical Center, Oakland, California 94602, USA.
| | | | | |
Collapse
|
44
|
De Paolis P, Porcellini A, Savoia C, Lombardi A, Gigante B, Frati G, Rubattu S, Musumeci B, Volpe M. Functional cross-talk between angiotensin II and epidermal growth factor receptors in NIH3T3 fibroblasts. J Hypertens 2002; 20:693-9. [PMID: 11910305 DOI: 10.1097/00004872-200204000-00027] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The main angiotensin (Ang) II subtype receptors (AT1R and AT2R) are involved in cellular growth processes and exert functionally antagonistic effects. OBJECTIVE To characterize the mechanisms by which Ang II receptors influence growth, by investigating the interactions between Ang II subtype receptors and epidermal growth factor (EGF) receptors on mitogen-activated protein kinase (MAPK) pathway activation. DESIGN AND METHODS The experiments were performed using a mouse fibroblast cell line, NIH3T3, by transient co-transfection with rat AT1R or AT2R expression vectors, or both. Extracellular-signal-regulated kinase (ERK)1/2 phosphorylation was analysed by western blot and the ERK activity was evaluated using PathDetect, an in-vivo signal transduction pathway trans-reporting system. Selective Ang II receptor antagonists (losartan for AT1R and PD123319 for AT2R) were used to investigate the contributions of each receptor to the response observed. RESULTS Our data show that, in this cellular model, both Ang II receptors phosphorylate ERK1/2. However, in the cells expressing AT1R, the EGF-induced MAPK pathway was enhanced in the presence of Ang II in a synergistic fashion. In contrast, a reduction of EGF-induced MAPK activation was observed in the cells expressing AT2R. In cells expressing both Ang II subtype receptors, Ang II promoted an enhancement of EGF-induced MAPK activation. However, in the presence of the AT1R antagonist, losartan, the effect of EGF was reduced. CONCLUSION These data indicate the existence of an opposite cross-talk of AT1R and AT2R with EGF receptors, and suggest a complex functional interaction between these pathways in the regulation of cellular growth processes.
Collapse
Affiliation(s)
- Paola De Paolis
- IRCSS Istituto Neurologico Mediterraneo Neuromed, Via Atinense 18, Località Camerelle, Pozzilli (Is), Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Rubattu S, Giliberti R, De Paolis P, Stanzione R, Spinsanti P, Venturelli V, Volpe M. Effect of a regulatory mutation on the rat atrial natriuretic peptide gene transcription. Peptides 2002; 23:555-60. [PMID: 11836006 DOI: 10.1016/s0196-9781(01)00626-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To investigate the functional relevance of a regulatory mutation affecting the enhancer element PEA2 of the rat ANP gene we transfected rat cardiomyocytes and aortic endothelial cells with either the mutant or the wild-type ANP promoter construct (-683 +54) and performed CAT assays both at baseline and in response to Phenylephrine and Angiotensin II. In the myocardial cells we also determined the DNA/nuclear protein interaction through electrophoretic mobility shift assay. These studies showed a significantly lower degree of ANP transcription in the presence of the mutant PEA2 site, thus demonstrating its functional significance and the biological relevance of ANP gene structural alterations.
Collapse
Affiliation(s)
- Speranza Rubattu
- Istituto Neuromed, Polo Molisano dell'Universita' La Sapienza di Roma, Pozzilli, Italy.
| | | | | | | | | | | | | |
Collapse
|