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Špiranec K, Chen W, Werner F, Nikolaev VO, Naruke T, Koch F, Werner A, Eder-Negrin P, Diéguez-Hurtado R, Adams RH, Baba HA, Schmidt H, Schuh K, Skryabin BV, Movahedi K, Schweda F, Kuhn M. Endothelial C-Type Natriuretic Peptide Acts on Pericytes to Regulate Microcirculatory Flow and Blood Pressure. Circulation 2019; 138:494-508. [PMID: 29626067 DOI: 10.1161/circulationaha.117.033383] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Peripheral vascular resistance has a major impact on arterial blood pressure levels. Endothelial C-type natriuretic peptide (CNP) participates in the local regulation of vascular tone, but the target cells remain controversial. The cGMP-producing guanylyl cyclase-B (GC-B) receptor for CNP is expressed in vascular smooth muscle cells (SMCs). However, whereas endothelial cell-specific CNP knockout mice are hypertensive, mice with deletion of GC-B in vascular SMCs have unaltered blood pressure. METHODS We analyzed whether the vasodilating response to CNP changes along the vascular tree, ie, whether the GC-B receptor is expressed in microvascular types of cells. Mice with a floxed GC-B ( Npr2) gene were interbred with Tie2-Cre or PDGF-Rβ-Cre ERT2 lines to develop mice lacking GC-B in endothelial cells or in precapillary arteriolar SMCs and capillary pericytes. Intravital microscopy, invasive and noninvasive hemodynamics, fluorescence energy transfer studies of pericyte cAMP levels in situ, and renal physiology were combined to dissect whether and how CNP/GC-B/cGMP signaling modulates microcirculatory tone and blood pressure. RESULTS Intravital microscopy studies revealed that the vasodilatatory effect of CNP increases toward small-diameter arterioles and capillaries. CNP consistently did not prevent endothelin-1-induced acute constrictions of proximal arterioles, but fully reversed endothelin effects in precapillary arterioles and capillaries. Here, the GC-B receptor is expressed both in endothelial and mural cells, ie, in pericytes. It is notable that the vasodilatatory effects of CNP were preserved in mice with endothelial GC-B deletion, but abolished in mice lacking GC-B in microcirculatory SMCs and pericytes. CNP, via GC-B/cGMP signaling, modulates 2 signaling cascades in pericytes: it activates cGMP-dependent protein kinase I to phosphorylate downstream targets such as the cytoskeleton-associated vasodilator-activated phosphoprotein, and it inhibits phosphodiesterase 3A, thereby enhancing pericyte cAMP levels. These pathways ultimately prevent endothelin-induced increases of pericyte calcium levels and pericyte contraction. Mice with deletion of GC-B in microcirculatory SMCs and pericytes have elevated peripheral resistance and chronic arterial hypertension without a change in renal function. CONCLUSIONS Our studies indicate that endothelial CNP regulates distal arteriolar and capillary blood flow. CNP-induced GC-B/cGMP signaling in microvascular SMCs and pericytes is essential for the maintenance of normal microvascular resistance and blood pressure.
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Affiliation(s)
- Katarina Špiranec
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
| | - Wen Chen
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
| | - Franziska Werner
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
| | - Viacheslav O Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Germany (V.O.N.)
| | - Takashi Naruke
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
| | - Franziska Koch
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
| | - Andrea Werner
- Institute of Physiology, University of Regensburg, Germany (A.W., F.S.)
| | - Petra Eder-Negrin
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
| | - Rodrigo Diéguez-Hurtado
- Max-Planck-Institute for Molecular Biomedicine, Department of Tissue Morphogenesis (R.D.-H., R.H.A.)
| | - Ralf H Adams
- Max-Planck-Institute for Molecular Biomedicine, Department of Tissue Morphogenesis (R.D.-H., R.H.A.)
| | - Hideo A Baba
- Faculty of Medicine, University of Münster, Germany. Institute of Pathology, University Hospital Essen, University Duisburg-Essen, Germany (H.A.B.)
| | - Hannes Schmidt
- Interfaculty Institute of Biochemistry, University of Tübingen, Germany (H.S.)
| | - Kai Schuh
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
| | - Boris V Skryabin
- Core Facility Transgenic Animal and genetic engineering Models (B.V.S.)
| | - Kiavash Movahedi
- Myeloid Cell Immunology Lab, Vesalius Research Center, Center for Inflammation Research, and Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium (K.M.)
| | - Frank Schweda
- Institute of Physiology, University of Regensburg, Germany (A.W., F.S.)
| | - Michaela Kuhn
- Institute of Physiology, University of Würzburg and Comprehensive Heart Failure Center, University Hospital Würzburg, Germany (K. Špiranec, W.C., S.C., F.W., T.N., F.K., P.E.-N., K. Schuh, M.K.)
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Abstract
Natriuretic peptides are structurally related, functionally diverse hormones. Circulating atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are delivered predominantly by the heart. Two C-type natriuretic peptides (CNPs) are paracrine messengers, notably in bone, brain, and vessels. Natriuretic peptides act by binding to the extracellular domains of three receptors, NPR-A, NPR-B, and NPR-C of which the first two are guanylate cyclases. NPR-C is coupled to inhibitory proteins. Atrial wall stress is the major regulator of ANP secretion; however, atrial pressure changes plasma ANP only modestly and transiently, and the relation between plasma ANP and atrial wall tension (or extracellular volume or sodium intake) is weak. Absence and overexpression of ANP-related genes are associated with modest blood pressure changes. ANP augments vascular permeability and reduces vascular contractility, renin and aldosterone secretion, sympathetic nerve activity, and renal tubular sodium transport. Within the physiological range of plasma ANP, the responses to step-up changes are unimpressive; in man, the systemic physiological effects include diminution of renin secretion, aldosterone secretion, and cardiac preload. For BNP, the available evidence does not show that cardiac release to the blood is related to sodium homeostasis or body fluid control. CNPs are not circulating hormones, but primarily paracrine messengers important to ossification, nervous system development, and endothelial function. Normally, natriuretic peptides are not powerful natriuretic/diuretic hormones; common conclusions are not consistently supported by hard data. ANP may provide fine-tuning of reno-cardiovascular relationships, but seems, together with BNP, primarily involved in the regulation of cardiac performance and remodeling. © 2017 American Physiological Society. Compr Physiol 8:1211-1249, 2018.
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Affiliation(s)
- Peter Bie
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
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An Acute Bout of Aquatic Treadmill Exercise Induces Greater Improvements in Endothelial Function and Postexercise Hypotension Than Land Treadmill Exercise: A Crossover Study. Am J Phys Med Rehabil 2018; 97:578-584. [PMID: 29547447 DOI: 10.1097/phm.0000000000000923] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE The purpose of the study was to compare acute bouts of aquatic treadmill (ATM) and land treadmill (LTM) exercise on flow-mediated dilation, postexercise blood pressure, plasma nitrate/nitrite, and atrial natriuretic peptide in untrained, prehypertensive men. DESIGN In a counterbalanced, crossover design, 19 untrained, prehypertensive men completed bouts of ATM and LTM on separate days. Flow-mediated dilation was measured pre-exercise and 1-hr postexercise. Blood samples were obtained pre-exercise and immediately postexercise and analyzed for plasma nitrate/nitrite and atrial natriuretic peptide. A magnitude-based inference approach to inference was used for statistical analysis. RESULTS A possible clinically beneficial increase in flow-mediated dilation (1.2%, 90% confidence interval = -0.07% to 2.5%) was observed 1 hr after ATM. In contrast, a possible clinically harmful decrease in flow-mediated dilation (-1.3%, 90% confidence interval = -2.7% to 0.2%) was observed 1 hr after LTM. The magnitude of the postexercise systolic blood pressure reduction was greater after ATM (-4.9, SD = 2.9 mm Hg) than LTM (-2.6, SD = 2.5 mm Hg). Atrial natriuretic peptide increased 34.3 (SD = 47.0%) after ATM and decreased -9.0 (SD = 40.0%) after LTM. CONCLUSIONS An acute bout of ATM induced a more favorable endothelial response and greater postexercise hypotensive response than LTM. These changes were associated with increased atrial natriuretic peptide levels after ATM.
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Edvinsson ML, Ahnstedt H, Edvinsson L, Andersson SE. Characterization of Relaxant Responses to Natriuretic Peptides in the Human MicrocirculationIn VitroandIn Vivo. Microcirculation 2016; 23:438-46. [DOI: 10.1111/micc.12290] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 05/17/2016] [Indexed: 01/22/2023]
Affiliation(s)
| | - Hilda Ahnstedt
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University; Lund Sweden
| | - Lars Edvinsson
- Department Emergency Medicine; Skane University Hospital; Lund Sweden
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University; Lund Sweden
| | - Sven E. Andersson
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University; Lund Sweden
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Cannone V, Cefalu' AB, Noto D, Scott CG, Bailey KR, Cavera G, Pagano M, Sapienza M, Averna MR, Burnett JC. The atrial natriuretic peptide genetic variant rs5068 is associated with a favorable cardiometabolic phenotype in a Mediterranean population. Diabetes Care 2013; 36:2850-6. [PMID: 23637347 PMCID: PMC3747944 DOI: 10.2337/dc12-2337] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE We hypothesized that the minor allele of the atrial natriuretic peptide (ANP) genetic variant rs5068 is associated with a favorable cardiometabolic phenotype in a general Mediterranean population. RESEARCH DESIGN AND METHODS We genotyped a random sample of the residents of Ventimiglia di Sicilia, Sicily, for rs5068. RESULTS Genotype frequencies of rs5068 are AA, 93.5%; AG, 6.4%; and GG, 0.1%. All subsequent analyses are AA versus AG+GG. After adjusting for age and sex, the minor G allele is associated with lower BMI (estimate [SE]: -1.7 kg/m(2) [0.8], P = 0.04). In the AG+GG group, males with HDL cholesterol levels <40 mg/dL are less frequent (P = 0.05) and obesity tends to be less prevalent (P = 0.07). Importantly, the G allele is associated with a lower prevalence of metabolic syndrome (P = 0.02). After adjusting for BMI, the above associations were attenuated. Independently of age, sex, and BMI, the minor allele is also associated with lower systolic blood pressure (-6.0 mmHg [2.5], P = 0.02) and lower prevalence of hypertension (odds ratio 0.41 [95% CI 0.20-0.83], P = 0.01). CONCLUSIONS The association between the minor allele of rs5068 and a favorable cardiometabolic phenotype that we previously reported in a U.S. population is now replicated in a Mediterranean population in which the G allele of rs5068 is associated with lower blood pressure, BMI, and prevalence of hypertension and metabolic syndrome. These findings may lead to a diagnostic strategy to assess cardiometabolic risk and lay the foundation for the future development of an ANP or ANP-like therapy for metabolic syndrome.
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Affiliation(s)
- Valentina Cannone
- Cardiorenal Research Laboratory, Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA.
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Tankersley CG, Georgakopoulos D, Tang WY, Abston E, Bierman A, Sborz N. Effects of ozone and particulate matter on cardiac mechanics: role of the atrial natriuretic peptide gene. Toxicol Sci 2012; 131:95-107. [PMID: 22977167 DOI: 10.1093/toxsci/kfs273] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
A positive association between air pollution exposure and increased human risk of chronic heart disease progression is well established. In the current study, we test two hypotheses: (1) the cardiac compensatory changes in response to air pollution are dependent on its composition and (2) specific cardiac adaptations are regulated by atrial natriuretic peptide (ANP). We address these hypotheses by initially examining the exposure effects of ozone (O(3)) and/or particulate matter (PM) on cardiac function in C57Bl/6J (B6) mice. Subsequently, the results are compared with cardiac functional changes to the same exposures in Nppa (the precursor gene for ANP) knockout (KO) mice. Separate groups of mice underwent 3 consecutive days of the same exposure sequence for 3h each consisting of the following: (1) 6h of filtered air (FAFA), (2) O(3) then FA (O(3)FA), (3) FA then carbon black (FACB), or (4) O(3) then CB. Cardiac function was assessed using a conductance catheter to generate cardiac pressure-volume loops 8-10h following each exposure sequence. As compared with FAFA, each sequence led to a substantial drop (as much as 33%) in stroke volume and cardiac output. However, these losses of cardiac function occurred by different compensatory mechanisms dependent on the pollutant composition. For example, O(3)FA exposure led to reductions in both end-systolic and end-diastolic left ventricular (LV) volumes, whereas FACB exposure led an increase in end-diastolic LV volume. These same cardiac compensatory changes were largely abolished in Nppa KO mice following O(3)FA or FACB exposure. These results suggest that cardiac functional changes in response to air pollution exposure are strongly dependent on the pollutant constituents, especially related to O(3) and/or PM. Furthermore, ANP regulation appears to be crucial to these cardiac compensatory mechanisms induced by air pollution.
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Affiliation(s)
- Clarke G Tankersley
- Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland 21205, USA.
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Endlich PW, Firmes LB, Gonçalves WLS, Gouvea SA, Moysés MR, Bissoli NS, Reis AM, Abreu GR. Involvement of the atrial natriuretic peptide in the reduction of arterial pressure induced by swimming but not by running training in hypertensive rats. Peptides 2011; 32:1706-12. [PMID: 21762739 DOI: 10.1016/j.peptides.2011.06.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Revised: 06/28/2011] [Accepted: 06/28/2011] [Indexed: 11/23/2022]
Abstract
The aim of this study was to compare, under resting conditions, the influence of chronic training in swimming or running on mean arterial pressure (MAP) and the involvement of the natriuretic peptide system in this response. Two-month-old male spontaneously hypertensive rats (SHR) were divided into three groups-sedentary (SD), swimming (SW) and running (RN)-and were trained for eight weeks under regimens of similar intensities. Atria tissue and plasma atrial natriuretic peptide (ANP) concentrations were measured by radioimmunoassay. ANP mRNA levels in the right and left atria as well as the natriuretic peptide receptors (NPR), NPR-A and NPR-C, mRNA levels in the kidney were determined by real-time PCR. Autoradiography was used to quantify NPR-A and NPR-C in mesenteric adipose tissue. Both training modalities, swimming and running, reduced the mean arterial pressure (MAP) of SHR. Swimming, but not running, training increased plasma levels of ANP compared to the sedentary group (P<0.05). Expression of ANP mRNA in the left atrium was reduced in the RN compared to the SD group (P<0.05). Expression of NPR-A and NPR-C in the kidneys of the SW group decreased significantly (P<0.05) compared to the SD group. Although swimming increased (125)I-ANP binding to mesenteric adipose tissue, displacement by c-ANF was reduced, indicating a reduction of NPR-C. These results suggest that the MAP reduction induced by exercise in SHR differs in its mechanisms between the training modalities, as evidenced by the finding that increased levels of ANP were only observed after the swimming regimen.
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Affiliation(s)
- Patrick W Endlich
- Department of Physiological Sciences, Health Sciences Center, Federal University of Espírito Santo, Espírito Santo, Vitória-ES, Brazil.
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8
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Porzionato A, Macchi V, Rucinski M, Malendowicz LK, De Caro R. Natriuretic Peptides in the Regulation of the Hypothalamic–Pituitary–Adrenal Axis. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 280:1-39. [DOI: 10.1016/s1937-6448(10)80001-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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O'Tierney PF, Tse MY, Pang SC. Elevated renal norepinephrine in proANP gene-disrupted mice is associated with increased tyrosine hydroxylase expression in sympathetic ganglia. ACTA ACUST UNITED AC 2007; 143:90-6. [PMID: 17482290 DOI: 10.1016/j.regpep.2007.03.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 01/03/2007] [Accepted: 03/31/2007] [Indexed: 11/18/2022]
Abstract
The sympatholytic properties of atrial natriuretic peptide (ANP) contribute to its vasodilatory and natriuretic effects. High circulating catecholamine levels, along with renal dysfunction, present in proANP gene-disrupted (-/-) mice are thought to contribute to the hypertension characteristic of this model. To further understand the mechanism by which the absence of ANP leads to stimulation of sympathetic activity we measured tyrosine hydroxylase expression in mice with and without ANP. The adrenal and prevertebral ganglionic expression of tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine production, was significantly increased in ANP -/- mice. ANP's sympatholytic properties include the depression of ganglionic and adrenal TH expression and catecholamine production. Thus, these results suggest that the absence of ANP's sympatholytic effects is not completely compensated for in ANP -/- mice. In addition, mice devoid of ANP display an increase in renal sympathetic nerve activity from birth through to adulthood which may lead to structural and/or functional changes in the early postnatal kidney that contribute to the hypertensive phenotype of ANP -/- mice. The over-activation of the sympathetic nervous system in mice lacking ANP confirms the important role of this peptide in the modulation of sympathetic nerve activity and its contribution to blood pressure homeostasis.
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Affiliation(s)
- Perrie F O'Tierney
- Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
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Li X, Woodard GE, Brown J, Rosado JA. Renal atrial natriuretic peptide receptors binding properties and function are resistant to DOCA-salt-induced hypertension in rats. ACTA ACUST UNITED AC 2006; 137:114-20. [PMID: 16904201 DOI: 10.1016/j.regpep.2006.06.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2006] [Revised: 05/27/2006] [Accepted: 06/12/2006] [Indexed: 11/22/2022]
Abstract
Atrial natriuretic peptide receptor types A (NPR-A) and C (NPR-C) binding properties and functional characteristics in renal glomeruli have been investigated in deoxycorticosterone acetate (DOCA)-treated hypertensive Wistar-Kyoto (WKY) rats and their respective controls. We found that DOCA administration had no significant effect on the maximum binding capacity or the affinity of renal NPR-A and NPR-C. NPR-C is involved in the regulation of cAMP production. Our results indicate that the cAMP production by NPR-C is not altered in DOCA-induced hypertension, since ANP(1-28), CNP(1-22) and C-ANP, which specifically bind to NPR-C, show a similar inhibitory effect on cAMP production stimulated by the physiological agonist histamine in glomeruli from DOCA-treated rats and controls. Finally, we have found that DOCA-induced hypertension does not modify NPR-A or NPR-C expression in rat glomerular membranes. These findings indicate that NPR-A and NPR-C binding properties and NPR-C-mediated inhibition of cAMP generation remain unaltered in DOCA-treated rats.
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Affiliation(s)
- Xiaohong Li
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 10, Rm 8C-208, 10 Center Drive, MSC 1752, Bethesda, MD 20892-1752, USA.
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11
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Garbers DL, Chrisman TD, Wiegn P, Katafuchi T, Albanesi JP, Bielinski V, Barylko B, Redfield MM, Burnett JC. Membrane guanylyl cyclase receptors: an update. Trends Endocrinol Metab 2006; 17:251-8. [PMID: 16815030 PMCID: PMC2647281 DOI: 10.1016/j.tem.2006.06.006] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Revised: 06/07/2006] [Accepted: 06/16/2006] [Indexed: 11/17/2022]
Abstract
Recent studies have demonstrated key roles for several membrane guanylyl cyclase receptors in the regulation of cell hyperplasia, hypertrophy, migration and extracellular matrix production, all of which having an impact on clinically relevant diseases, including tissue remodeling after injury. Additionally, cell differentiation, and even tumor progression, can be profoundly influenced by one or more of these receptors. Some of these receptors also mediate important communication between the heart and intestine, and the kidney to regulate blood volume and Na+ balance.
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Affiliation(s)
- David L Garbers
- Cecil H. & Ida Green Center for Reproductive Biology Sciences, and Department of Pharmacology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390-9051, USA.
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12
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Mukaddam-Daher S, Menaouar A, Gutkowska J. Receptors involved in moxonidine-stimulated atrial natriuretic peptide release from isolated normotensive rat hearts. Eur J Pharmacol 2006; 541:73-9. [PMID: 16774751 DOI: 10.1016/j.ejphar.2006.05.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Revised: 04/27/2006] [Accepted: 05/08/2006] [Indexed: 10/24/2022]
Abstract
Imidazoline I1-receptors are present in the heart and may be involved in atrial natriuretic peptide (ANP) release. The following studies investigated whether moxonidine (an antihypertensive imidazoline I1-receptor and alpha2-adrenoceptor agonist) acts directly on the heart to stimulate ANP release, and to characterize the receptor type involved in this action. Perfusion of rat (200-225 g) isolated hearts with moxonidine (10(-6) and 10(-5) M), for 30 min, resulted in ANP release (83+/-29 and 277+/-70 ng/30 min, above basal, respectively), significantly (P<0.01) different from perfusion with buffer (-6+/-31 ng/30 min). ANP release stimulated by moxonidine (10(-6) M) was inhibited by co-perfusion with the antagonists, AGN192403 (imidazoline I1-receptor), phenoxybenzamine (alpha2>alpha1-adrenoceptors), and prazosin (alpha1>alpha2-adrenoceptors), but increased by rauwolscine (alpha2-adrenoceptors). Perfusion with 10(-5) M brimonidine (full alpha2-adrenoceptor agonist) inhibited moxonidine-stimulated ANP release. Similarly, moxonidine (10(-6) M) tended to reduce coronary flow, but significantly increased coronary flow in the presence of brimonidine, which was vasoconstrictive when perfused alone. Coronary flow was reduced by 10(-5) M each, brimonidine>clonidine>moxonidine; while similar bradycardia was observed with clonidine and moxonidine, but not with brimonidine. In conclusion, these results argue in favor of moxonidine acting primarily on imidazoline I1-receptors to release ANP, with both alpha2-adrenoceptor and imidazoline I1-receptors exerting inhibitory inter-relation. In contrast, the coronary vasodilatory effect of moxonidine requires full activation of alpha2-adrenoceptor. The sympatholytic and ANP-releasing effects of moxonidine appear to be mediated by cardiac imidazoline receptors that may be differentially localized. Most importantly, moxonidine can stimulate ANP release from the heart without contribution of the central nervous system.
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Affiliation(s)
- Suhayla Mukaddam-Daher
- Centre Hospitalier de L'Université de Montréal Research Center, Campus Hotel-Dieu, Montréal, Quebec, Canada
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Abstract
In this review, we outline the application and contribution of transgenic technology to establishing the genetic basis of blood pressure regulation and its dysfunction. Apart from a small number of examples where high blood pressure is the result of single gene mutation, essential hypertension is the sum of interactions between multiple environmental and genetic factors. Candidate genes can be identified by a variety of means including linkage analysis, quantitative trait locus analysis, association studies, and genome-wide scans. To test the validity of candidate genes, it is valuable to model hypertension in laboratory animals. Animal models generated through selective breeding strategies are often complex, and the underlying mechanism of hypertension is not clear. A complementary strategy has been the use of transgenic technology. Here one gene can be selectively, tissue specifically, or developmentally overexpressed, knocked down, or knocked out. Although resulting phenotypes may still be complicated, the underlying genetic perturbation is a starting point for identifying interactions that lead to hypertension. We recognize that the development and maintenance of hypertension may involve many systems including the vascular, cardiac, and central nervous systems. However, given the central role of the kidney in normal and abnormal blood pressure regulation, we intend to limit our review to models with a broadly renal perspective.
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Affiliation(s)
- Linda J Mullins
- Molecular Physiology Laboratory, Centre for Cardiovascular Science, Queens Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
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Kulandavelu S, Qu D, Adamson SL. Cardiovascular function in mice during normal pregnancy and in the absence of endothelial NO synthase. Hypertension 2006; 47:1175-82. [PMID: 16636199 DOI: 10.1161/01.hyp.0000218440.71846.db] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In humans, the increased cardiovascular demands of pregnancy are met by increases in cardiac output (CO), stroke volume (SV), plasma volume (PV), and cardiac and aortic inner dimensions and a concurrent decrease in arterial pressure that indicates a fall in total peripheral vascular resistance. The mechanisms responsible for these changes are incompletely understood, but NO synthase (NOS) is believed to play a central role. We assessed whether C57Bl/6J (B6) mice show similar changes and whether these changes are altered in mice lacking the gene for endothelial NOS (eNOS). The CO of B6 mice increased 28% by day 9.5 of gestation because of a 25% increase in SV, and increased 48% by day 17.5 because of a 41% increase in SV. The increase in SV at day 17.5 was associated with a 27% increase in PV, a 15% decrease in arterial pressure, and 10% to 15% increases in aortic and left-ventricular inner dimensions. In the absence of eNOS, CO increased 22% by day 9.5 because of increases in SV (14%) and heart rate (9%), but increased no further by day 17.5. SV near term was lower than B6 mice despite similar 26% increases in PV and 14% decreases in arterial pressure in association with blunted left-ventricular chamber enlargement. All reported changes are P<0.05. We conclude that cardiovascular changes during pregnancy are similar in B6 mice and humans. eNOS plays a critical role in increasing stroke volume in late gestation by promoting cardiac remodeling.
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Abstract
Natriuretic peptides (atrial natriuretic peptide, brain natriuretic peptide and C-type natriuretic peptide) are cardiac and vascular peptides with vasodilatory, diuretic, natriuretic, anti-inflammatory, antifibrotic and antimitogenic actions. Natriuretic peptides are implicated in normal pressure and volume homeostasis and in the defence against excessive increases in overload-related factors, vasopressive and cardiotoxic factors and their impact on the heart, blood vessels and brain. Genetic manipulation studies confirmed the importance of natriuretic peptides in these functions. Natriuretic peptides are metabolised by NPR-C (clearance receptors) and by enzymatic degradation by neutral endopeptidase. Natriuretic peptide levels (mainly brain natriuretic peptide) correlate with left ventricular hypertrophy and with the severity of heart failure, and are reduced by effective treatment, thus used as diagnostic and prognostic tools. Based on the multiple protective effects of natriuretic peptides, pharmacological therapy has been approved and includes potentiating natriuretic peptide levels by intravenous infusion or by inhibition of endogenous natriuretic peptide degradation. Because each approach has its limitations, the field remains open for improvement.
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Affiliation(s)
- Suhayla Mukaddam-Daher
- Centre Hospitalier de L'Université de Montréal Research Center, Laboratory of Cardiovascular Biochemistry, 3840 St-Urbain Street (6-816), Montreal, Quebec, Canada.
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16
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Zineh I, Schofield RS, Johnson JA. The Evolving Role of Nesiritide in Advanced or Decompensated Heart Failure. Pharmacotherapy 2003; 23:1266-80. [PMID: 14594345 DOI: 10.1592/phco.23.12.1266.32705] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Nesiritide is a recombinant form of human brain natriuretic peptide (BNP) that is structurally and biochemically identical to endogenously produced BNP. In humans, BNP is important in hemodynamic and neurohormonal equilibrium, helping to maintain adequate vascular volume and pressure in response to volume overload. The pharmacodynamic effects of nesiritide mimic the biologic effects of BNP. The molecular biology and actions of nesiritide and BNP are reviewed, with the therapeutic rationale for nesiritide in patients with acute or advanced decompensated heart failure highlighted. In addition, recommendations for its administration are provided, and unresolved therapeutic considerations are discussed.
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Affiliation(s)
- Issam Zineh
- Department of Pharmacy Practice, College of Pharmacy, University of Florida, P.O. Box 100486, Gainesville, FL 32610, USA.
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17
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Bulut D, Potthast R, Hanefeld C, Schulz T, Kuhn M, Mügge A. Impaired vasodilator responses to atrial natriuretic peptide in essential hypertension. Eur J Clin Invest 2003; 33:567-73. [PMID: 12814393 DOI: 10.1046/j.1365-2362.2003.01188.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Atrial natriuretic peptide (ANP) has vasodilating and diuretic/natriuretic properties, both of which contribute to lower blood pressure. These effects are mediated by binding of ANP to a cell-surface receptor [type A guanylyl cyclase (GC-A)]. It has been demonstrated by studies in monogenetic mouse models that the ANP/GC-A system participates in the maintenance of blood pressure homeostasis. METHODS In male patients with essential hypertension (EH; n = 36) as the only cardiovascular risk factor and normotensive controls (n = 12), blood flow was measured in the forearm circulation in response to i.a. infusion of synthetic human ANP, acetylcholine, orciprenaline, and sodium nitroprusside by strain-gauge venous plethysmography. In blood samples, cyclic guanosine'5-monophosphate (cGMP) and ANP concentrations were measured at resting conditions and during exogenous ANP infusion. In 200 patients with EH, genomic DNA was screened for an inhibitory deletion mutation of the GC-A gene, which has been recently linked to EH in a Japanese cohort. RESULTS The vasodilatations in response to ANP and acetylcholine were impaired in the forearm circulation of patients with EH, whereas the responses to orciprenaline and nitroprusside were preserved. Plasma ANP and cGMP concentrations were increased in the patients with EH both at resting conditions and during ANP infusion; the resting plasma cGMP levels correlated significantly with the plasma ANP levels (r = 0.68). A specific deletion mutation of the GC-A gene did not account for the diminished relaxant effects of ANP in our study population. CONCLUSIONS The vascular ANP/GC-A pathway is altered in patients with EH, in addition to the known defects on the nitric oxide/cGMP pathway. Attenuation of the vasodilative responses to ANP suggests impaired receptor or postreceptor responsiveness of GC-A. It is possible that this dysfunction participates in the pathomechanism of EH.
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Affiliation(s)
- D Bulut
- Clinic of Cardiology and Angiology, St. Josef-Hospital/Bergmannsheil, Ruhr-University Bochum, Gudrunstrasse 56, 44791 Bochum, Germany
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18
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Calderone A. The therapeutic effect of natriuretic peptides in heart failure; differential regulation of endothelial and inducible nitric oxide synthases. Heart Fail Rev 2003; 8:55-70. [PMID: 12652160 DOI: 10.1023/a:1022147005110] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The abnormal regulation of nitric oxide synthase activity represents an underlying feature of heart failure. Increased peripheral vascular resistance, and decreased renal function may be in part related to impaired endothelium-dependent nitric oxide (NO) synthesis. Paradoxically, the chronic production of NO by inducible nitric oxide synthase (iNOS) in heart failure exerts deleterious effects on ventricular contractility, and circulatory function. Consequently, pharmacologically improving endothelium-dependent NO synthesis and the concomitant inhibition of iNOS activity would be therapeutically advantageous. Interestingly, natriuretic peptides have been shown to differentially regulate endothelial NOS (eNOS) and iNOS activity. Moreover, in both patients and animal models of heart failure, pharmacologically increasing plasma natriuretic peptide levels ameliorated vascular tone, renal function, and ventricular contractility. Based on these observations, the following review will explore whether the therapeutic benefit of the natriuretic peptide system in heart failure may occur in part via the amelioration of endothelium-dependent NO synthesis, and the concomitant inhibition of cytokine-mediated iNOS expression.
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Affiliation(s)
- Angelino Calderone
- Centre de Recherche de l'Institut de Cardiologie de Montréal, et Département de Physiologie, Université de Montréal, Montréal, Québec, Canada.
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19
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Holtwick R, Gotthardt M, Skryabin B, Steinmetz M, Potthast R, Zetsche B, Hammer RE, Herz J, Kuhn M. Smooth muscle-selective deletion of guanylyl cyclase-A prevents the acute but not chronic effects of ANP on blood pressure. Proc Natl Acad Sci U S A 2002; 99:7142-7. [PMID: 11997476 PMCID: PMC124542 DOI: 10.1073/pnas.102650499] [Citation(s) in RCA: 262] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Atrial natriuretic peptide (ANP) is an important regulator of arterial blood pressure. The mechanisms mediating its hypotensive effects are complex and involve the inhibition of the sympathetic and renin-angiotensin-aldosterone (RAA) systems, increased diuresis/natriuresis, vasodilation, and enhanced vascular permeability. In particular, the contribution of the direct vasodilating effect of ANP to the hypotensive actions remains controversial, because variable levels of the ANP receptor, guanylyl cyclase A (GC-A), are expressed in different vascular beds. The objective of our study was to determine whether a selective deletion of GC-A in vascular smooth muscle would affect the hypotensive actions of ANP. We first created a mutant allele of mouse GC-A by flanking a required exon with loxP sequences. Crossing floxed GC-A with SM22-Cre transgene mice expressing Cre recombinase in smooth muscle cells (SMC) resulted in mice in which vascular GC-A mRNA expression was reduced by approximately 80%. Accordingly, the relaxing effects of ANP on isolated vessels from these mice were abolished; despite this fact, chronic arterial blood pressure of awake SMC GC-A KO mice was normal. Infusion of ANP caused immediate decreases in blood pressure in floxed GC-A but not in SMC GC-A knockout mice. Furthermore, acute vascular volume expansion, which causes release of cardiac ANP, did not affect resting blood pressure of floxed GC-A mice, but rapidly and significantly increased blood pressure of SMC GC-A knockout mice. We conclude that vascular GC-A is dispensable in the chronic and critical in the acute moderation of arterial blood pressure by ANP.
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Affiliation(s)
- Rita Holtwick
- Institut für Pharmakologie und Toxikologie, Westfälische Wilhelms-Universität Münster, D-48149 Münster, Germany
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20
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Ryan MJ, Didion SP, Davis DR, Faraci FM, Sigmund CD. Endothelial dysfunction and blood pressure variability in selected inbred mouse strains. Arterioscler Thromb Vasc Biol 2002; 22:42-8. [PMID: 11788459 DOI: 10.1161/hq0102.101098] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The genetic regulation of blood pressure (BP) and endothelial function is likely to be polygenic. Because there is considerable variability in basal BP among inbred mouse strains, the purpose of this study was to determine whether a similar variability in vascular function exists among 7 "normotensive" strains. We tested the hypothesis that compared with mice with higher BPs, mice with lower BPs would have greater aortic endothelial responses to acetylcholine (ACh). Mean BP ranged from 117 to 145 mm Hg among the 7 strains. The responses of aortic rings to ACh, sodium nitroprusside, and papaverine were assessed after submaximal precontraction with prostaglandin F(2alpha). The aortas from all strains relaxed in a concentration-dependent manner to sodium nitroprusside and papaverine, but responses to ACh were markedly impaired in the aortas, but not carotid arteries, from 129P3/J and 129X1/SvJ mice. Aortas from the other strains relaxed normally to ACh. Furthermore, the endothelium-dependent dilators ADP and A23187 caused similar relaxation in 129P3/J, 129X1/SvJ, and C57BL/6J mice. Although the data do not support the initial hypothesis, the impaired aortic response to ACh in the 129 strains is a novel finding and illustrates the potential impact that genetic background can have on vascular responsiveness.
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Affiliation(s)
- Michael J Ryan
- Department of Internal Medicine, Cardiovascular Center, University of Iowa, Iowa City 52242, USA
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21
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Abstract
During the 1980s the purification, cloning, and expression of various forms of guanylyl cyclase (GC) revealed that they served as receptors for extracellular signals. Seven membrane forms, which presumably exist as homodimers, and four subunits of apparent heterodimers (commonly referred to as the soluble forms) are known, but in animals such as nematodes, much larger numbers of GCs are expressed. The number of transmembrane segments (none, one, or multiple) divide the GC family into three groups. Those with no or one transmembrane segment bind nitric oxide/carbon monoxide (NO/CO) or peptides. There are no known ligands for the multiple transmembrane segment class of GCs. Mutational and structural analyses support a model where catalysis requires a shared substrate binding site between the subunits, whether homomeric or heteromeric in nature. Because some cyclases or cyclase ligand genes lack specific GC inhibitors, disruption of either has been used to define the functions of individual cyclases, as well as to define human genetic disease counterparts.
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Affiliation(s)
- B Wedel
- Cecil H and Ida Green Center for Reproductive Biology Sciences, Howard Hughes Medical Institute and Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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22
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Ackermann U, Deliva RD. Reduced baroreceptor sensitivity during hypotension in ANP-knockout mice. Can J Physiol Pharmacol 2001. [DOI: 10.1139/y00-121] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We studied baroreflex gain in inactin-anesthetized mice that had been genetically modified to be depleted of atrial natriuretic peptide (ANP -/-). Wild-type mice (ANP +/+) served as controls. ANP -/- mice had a significantly higher basal arterial blood pressure (ABP) than ANP +/+ mice [112 ± 7 vs. 80 ± 5 mmHg (mean ± SEM)]. Their basal heart rates were not different (491 ± 13 vs. 446 ± 19 bpm). A third group, composed of ANP +/+ mice only, was rendered acutely hypertensive by an intravenous infusion of arginine vasopressin acetate (0.3 pg bolus followed by 0.3 pg/h) so as to serve as a control for the elevated ABP in the ANP -/- mice. Transient changes in ABP were caused by bolus injections of oxymetazoline hydrochloride (1.5-3 ng) or sodium nitroprusside (20-100 ng). Baroreflex gain was calculated as the ratio of the peak heart rate change that followed the peak change in mean ABP resulting from injection of oxymetazoline or nitroprusside. There were no significant differences among the groups in their responses to transient hypertension. On the other hand, the ANP -/- mice showed a significantly depressed tachycardic response to transient hypotension when compared with the other two groups. We conclude that the ANP -/- mice are unable to increase efferent sympathetic nervous activity adequately above the high basal activity that is a feature of this animal model.Key words: atrial natriuretic peptides, knockouts, arterial blood pressure.
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23
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Melo LG, Steinhelper ME, Pang SC, Tse Y, Ackermann U. ANP in regulation of arterial pressure and fluid-electrolyte balance: lessons from genetic mouse models. Physiol Genomics 2000; 3:45-58. [PMID: 11015600 DOI: 10.1152/physiolgenomics.2000.3.1.45] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The recent development of genetic mouse models presenting life-long alterations in expression of the genes for atrial natriuretic peptide (ANP) or its receptors (NPR-A, NPR-C) has uncovered a physiological role of this hormone in chronic blood pressure homeostasis. Transgenic mice overexpressing a transthyretin-ANP fusion gene are hypotensive relative to the nontransgenic littermates, whereas mice harboring functional disruptions of the ANP or NPR-A genes are hypertensive compared with their respective wild-type counterparts. The chronic hypotensive action of ANP is determined by vasodilation of the resistance vasculature, which is probably mediated by attenuation of vascular sympathetic tone at one or several prejunctional sites. Under conditions of normal dietary salt consumption, the hypotensive action of ANP is dissociated from the natriuretic activity of the hormone. However, during elevated dietary salt intake, ANP-mediated antagonism of the renin-angiotensin system is essential for maintenance of blood pressure constancy, inasmuch as the ANP gene "knockout" mice (ANP -/-) develop a salt-sensitive component of hypertension in association with failure to adequately downregulate plasma renin activity. These findings imply that genetic deficiencies in ANP or natriuretic receptor activity may be underlying causative factors in the etiology of salt-sensitive variants of hypertensive disease and other sodium-retaining disorders, such as congestive heart failure and cirrhosis.
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Affiliation(s)
- L G Melo
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada M5S 1A8.
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24
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Turk JR. Physiologic and pathophysiologic effects of natriuretic peptides and their implications in cardiopulmonary disease. J Am Vet Med Assoc 2000; 216:1970-6. [PMID: 10863599 DOI: 10.2460/javma.2000.216.1970] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- J R Turk
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri-Columbia 65205, USA
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25
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Melo LG, Pang SC, Ackermann U. Atrial Natriuretic Peptide: Regulator of Chronic Arterial Blood Pressure. NEWS IN PHYSIOLOGICAL SCIENCES : AN INTERNATIONAL JOURNAL OF PHYSIOLOGY PRODUCED JOINTLY BY THE INTERNATIONAL UNION OF PHYSIOLOGICAL SCIENCES AND THE AMERICAN PHYSIOLOGICAL SOCIETY 2000; 15:143-149. [PMID: 11390897 DOI: 10.1152/physiologyonline.2000.15.3.143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent findings in atrial natriuretic peptide (ANP) transgenic and gene knockout mouse models uncovered a tonic vasodilatory effect of this hormone that contributes to chronic blood pressure homeostasis. With elevated salt intake, ANP-mediated antagonism of the renin-angiotensin system is essential for blood pressure constancy, suggesting that a deficiency in ANP activity may underlie the etiology of sodium-retaining disorders.
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Affiliation(s)
- Luis Gabriel Melo
- Department of Physiology of the University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
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26
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Su X, Brower G, Janicki JS, Chen YF, Oparil S, Dell'Italia LJ. Differential expression of natriuretic peptides and their receptors in volume overload cardiac hypertrophy in the rat. J Mol Cell Cardiol 1999; 31:1927-36. [PMID: 10525429 DOI: 10.1006/jmcc.1999.1025] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) upregulation are genetic markers for the chronic hypertrophic phenotype but also have important acute physiologic effects on salt and water balance and blood pressure control. The presence of a dual NP-system led us to hypothesize a differential expression of ANP and BNP in response to an acute hemodynamic stress of volume overload in the left ventricle (LV) and right ventricle (RV). Accordingly, we examined the temporal relationship between the RV and LV expression of ANP and BNP mRNA and NP receptor mRNA levels on days 1, 2, 3, and 7 after induction of aortocaval fistula in the rat. LV end-diastolic pressure was increased 1.5-fold by day 3 and 2.0-fold by day 7 compared to control (P<0.05). LV weight increased by day 7 compared to control (2.34+/-0.04 vs 3.07+/-0.10 mg/g, P<0.05) while RV weight did not change over the 7 days. There was a 7-fold increase of ANP mRNA in LV at day 1, which was sustained through day 7, while LV BNP mRNA levels did not differ from controls over the 7 days. In contrast, RV mRNA transcript levels for ANP and BNP were increased >2-fold by day 2 and this increase was sustained throughout 7 days. NP clearance receptor was decreased by 75% by day 7 in the LV but did not change in the RV. Thus, LV ANP mRNA levels increased before the onset of LV hypertrophy and RV BNP mRNA levels increased in the absence of RV hypertrophy. The disparate response of BNP and the NP clearance receptor transcript levels in the LV and RV may be related to differences in load and/or differential expression of the NP system in the LV and RV in response to acute haemodynamic stress.
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Affiliation(s)
- X Su
- Department of Medicine, University of Alabama, Birmingham, Alabama 35294, USA
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