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Manolis AJ, Poulimenos LE, Kallistratos MS, Gavras I, Gavras H. Sympathetic overactivity in hypertension and cardiovascular disease. Curr Vasc Pharmacol 2014; 12:4-15. [PMID: 23905597 DOI: 10.2174/15701611113119990140] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 09/06/2012] [Accepted: 02/27/2013] [Indexed: 11/22/2022]
Abstract
From the first description of its anatomy by T. Willis to the novel therapeutic manipulations, it is unanimously recognized that the sympathetic nervous system (SNS) holds a crucial role in cardiovascular homeostasis. The introduction of sophisticated techniques, as microneurography and regional norepinephrine spillover provided the evidence for the role of sympathetic overactivity in various cardiovascular disease entities. Sympathetic activation is common in patients with essential hypertension and contributes to initiation, maintenance and progression of the disease and it contributes to the manifestation of its major complications. A considerable body of evidence relates SNS overactivity with high sodium intake in experimental animals and humans and the underlying mechanisms have nowadays been elucidated. SNS activity is more pronounced in patients with resistant hypertension and there are several conditions that lead to this phenomenon, as older age, kidney disease, obesity and metabolic syndrome, mental stress and sleep apnea. SNS overactivity holds also a key physiopathological role in heart failure, acute coronary syndromes and arrhythmias. Moreover, inhibition of sympathetic overactivity by various means, including central SNS suppressing drugs, peripheral alpha- and beta- adrenergic receptor blockers, or novel approaches as renal sympathetic denervation have been used successfully in the treatment of all these disorders.
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Affiliation(s)
| | | | | | | | - H Gavras
- Department of Cardiology, Asklepeion General Hospital, 1 Vas. Pavlou Ave, Voula 16673, Greece.
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2
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Marketou ME, Kontaraki J, Zacharis E, Parthenakis F, Maragkoudakis S, Gavras I, Gavras H, Vardas PE. Differential gene expression of bradykinin receptors 1 and 2 in peripheral monocytes from patients with essential hypertension. J Hum Hypertens 2014; 28:450-5. [PMID: 24401952 DOI: 10.1038/jhh.2013.133] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 11/07/2013] [Accepted: 11/19/2013] [Indexed: 12/26/2022]
Abstract
Bradykinin participates in various hypertensive processes, exerted via its type 1 and type 2 receptors (BKR1 and BKR2). The aim of the study was to investigate BKR1 and BK2R gene expression in peripheral monocytes in patients with essential hypertension compared with healthy individuals. Seventeen hypertensive patients (9 males, age 56 ± 7 years) and 12 healthy individuals (7 males, age 55 ± 6) participated. Mononuclear cells isolated using anti-CD14+ antibodies and mRNAs of BKR1 and BKR2 were estimated by real-time quantitative reverse transcription-PCR. Both BKR1 and BKR2 showed significantly upregulated gene expression in the group of hypertensive patients. Specifically, BKR1 gene expression was 142.1 ± 42.2 in hypertensives versus 20.2 ± 8 in controls (P = 0.024) and BKR2 was 1222.2 ± 361.6 in hypertensives versus 259.5 ± 99.1 in controls (P = 0.038). Antihypertensive treatment resulted in a decrease in BKR1 (from 142.1 ± 42.2 to 55.2 ± 17.1, P = 0.065) and in BKR2 (from 1222.2 ± 361.6 to 256.8 ± 81.8, P = 0.014) gene expression. BKR1 and BKR2 gene expression on peripheral monocytes is upregulated in essential hypertension. This may lead to functional changes in monocytes and contribute to the development of target organ damage in hypertensive patients.
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Affiliation(s)
- M E Marketou
- Cardiology Department, Heraklion University Hospital, Crete, Greece
| | - J Kontaraki
- Cardiology Department, Heraklion University Hospital, Crete, Greece
| | - E Zacharis
- Cardiology Department, Heraklion University Hospital, Crete, Greece
| | - F Parthenakis
- Cardiology Department, Heraklion University Hospital, Crete, Greece
| | - S Maragkoudakis
- Cardiology Department, Heraklion University Hospital, Crete, Greece
| | - I Gavras
- Hypertension and Atherosclerosis Section, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - H Gavras
- Hypertension and Atherosclerosis Section, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - P E Vardas
- Cardiology Department, Heraklion University Hospital, Crete, Greece
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3
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Marketou ME, Kintsurashvili E, Androulakis NE, Kontaraki J, Alexandrakis MG, Gavras I, Vardas PE, Gavras H. Blockade of platelet alpha2B-adrenergic receptors: A novel antiaggregant mechanism. Int J Cardiol 2013; 168:2561-6. [DOI: 10.1016/j.ijcard.2013.03.051] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 02/07/2013] [Accepted: 03/17/2013] [Indexed: 10/26/2022]
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4
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Marketou M, Kochiadakis G, Kintsurasvili E, Androulakis N, Giaouzaki A, Kontaraki J, Alexandrakis M, Gavras I, Gavras H, Vardas P. Blockade of platelet alpha2B-adrenergic receptors in patients with coronary artery disease: a novel antiaggregant mechanism. Eur Heart J 2013. [DOI: 10.1093/eurheartj/eht309.p3138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Marketou M, Kontaraki J, Zacharis E, Kochiadakis G, Gavras H, Gavras I, Vardas P. UPREGULATION OF BRADYKININ RECEPTORS 1 AND 2 GENE TRANSCRIPT LEVELS IN PERIPHERAL MONOCYTES IN PATIENTS WITH ESSENTIAL HYPERTENSION. J Am Coll Cardiol 2011. [DOI: 10.1016/s0735-1097(11)60530-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
After an early report that patients treated with angiotensin-converting enzyme (ACE) inhibitors had a lower than expected incidence of cancers, there was a large number of publications investigating the possible pathophysiological mechanism mediating this effect, as well as population studies comparing the incidence of cancers in patients treated with agents inhibiting the renin-angiotensin system with their incidence in the general population. Several mechanisms are proposed to explain a potential anti-tumour activity of such agents in vitro in experimental animal models. However, the population studies are mostly inconclusive, although they do suggest a possible interaction between ACE genotypes and susceptibility to altered behaviour of certain tumours.
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Affiliation(s)
- T Rosenthal
- Department of Physiology and Pharmacology, Hypertension Research Unit, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
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7
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Kintsurashvili E, Shenouda S, Ona D, Ona L, Ahmad S, Ravid K, Gavras I, Gavras H. Hypertension in transgenic mice with brain-selective overexpression of the alpha(2B)-adrenoceptor. Am J Hypertens 2009; 22:41-5. [PMID: 18989257 DOI: 10.1038/ajh.2008.314] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Previous studies have shown that the presynaptic alpha(2B)-adrenoceptor subtype in the central nervous system has a sympathoexcitatory function and its activation leads to a hyperadrenergic hypertensive state. The purpose of this project was to develop a novel hyperadrenergic model, a transgenic (TG) mouse model with brain-selective overexpression of the alpha(2B)-adrenergic receptor (alpha(2B)-AR). METHODS We used Southern blot analysis to confirm transgene, real-time PCR to assess gene expression, western Blot analysis and immunohistology to assess protein expression and localization in brain areas. Indirect blood pressure (BP) and heart rate were recorded. RESULTS In TG mice there was a 1.8-fold increase in alpha(2B)-AR protein expression compared to wild-type (WT) mice. Immunostaining of brain sections revealed that concentration of alpha(2B)-AR was much more pronounced in TG than in WT mice. Systolic BP at 8 weeks of age was significantly elevated in TG 130 +/- 6 mm Hg, compared with WT control nontransgenic littermates of the same age 107 +/- 7 mm Hg, (P < 0.05), indicating that the TG mice had indeed developed hypertension. CONCLUSIONS We have therefore documented that overexpression of the alpha(2B)-AR gene leads to increased production of alpha(2B)-AR protein in brain regions known to regulate central sympathetic outflow, thus resulting in sustained BP elevation. This is a unique model of experimental hypertension driven purely by overexpression of the alpha(2B)-AR that would result in an overactive sympathetic system and would be suitable for testing the pharmacologic properties of potential therapeutic agents.
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Silva VS, Martin LC, Franco RJS, Carvalho FC, Bregagnollo EA, Castro JH, Gavras I, Gavras H. Pleiotropic effects of statins may improve outcomes in atherosclerotic renovascular disease. Am J Hypertens 2008; 21:1163-8. [PMID: 18670414 DOI: 10.1038/ajh.2008.249] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Atherosclerotic renovascular disease (ARD) coexists with arterial obstructive disease in the coronary, cerebral, and peripheral arteries that may remain underdiagnosed and untreated. METHODS This retrospective study compares overall survival and renal survival (i.e., time to doubling of serum creatinine or end-stage renal disease (ESRD)) over an 11-year period in 104 ARD patients of whom 68 received statin therapy (group S) because of elevated lipid levels and 36 had no statin (group NS) because of normal lipid profile at entry. RESULTS Atherosclerosis in another vascular bed was documented in 84%. Lipid profiles at end point were virtually identical in both the groups. Group S had mean survival 123months (confidence interval (CI) 113-134) with four deaths, and mean renal survival 122months (CI 113-131). Group NS had mean survival 33 months (CI 23-42) with 13 deaths, and mean renal survival 27 months (CI 17-37). CONCLUSIONS Statin therapy was associated with lesser rate of progression of renal insufficiency (with 7.4% of S patients reaching renal end points vs. 38.9% of NS patients) and lower overall mortality (5.9 % in S vs. 36.1% in NS patients), P < 0.001 for both. Although both groups received what was deemed optimal therapy, they did have other differences that may have affected the outcomes (a limitation addressed by Cox multiple regression analysis). These results suggest the need for prospective randomized controlled studies in ARD patients in order to explore potential benefits of statins that may not be attributable solely to lipid lowering.
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Duka A, Kintsurashvili E, Duka I, Ona D, Hopkins TA, Bader M, Gavras I, Gavras H. Angiotensin-converting enzyme inhibition after experimental myocardial infarct: role of the kinin B1 and B2 receptors. Hypertension 2008; 51:1352-7. [PMID: 18347228 DOI: 10.1161/hypertensionaha.107.108506] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We sought to define the contribution of each of the 2 kinin receptors (bradykinin 1 receptor [B(1)R] and bradykinin 2 receptor [B(2)R]) to the cardioprotection of angiotensin-converting enzyme (ACE) inhibition after acute myocardial infarct. Wild-type mice and gene knockout mice missing either B(1)R or B(2)R were submitted to coronary ligation with or without concurrent ACE inhibition and had evaluation of left ventricular systolic capacity by assessment of fractional shortening (FS). Baseline FS was similar in all of the animals and remained unchanged in sham-operated ones. At 3 weeks after myocardial infarct, in the wild-type group there was a 27% reduction of FS (P<0.5) without ACE inhibition and 8% with ACE inhibition; in the B(1)R(-/-) groups the FS was reduced by 24% and was no different (at 28%) with ACE inhibition; in the B(2)R(-/-) groups, however, the FS was decreased by 39% and with ACE inhibition was decreased further by 52%. Analysis of bradykinin receptor gene expression in hearts showed that when one receptor was missing, the other became significantly upregulated; but the B(1)R remained highly overexpressed in the B(2)R(-/-) mice throughout, whereas the overexpressed B(2)R became significantly suppressed in the B(1)R(-/-) mice in a manner quantitatively and directionally similar to that of wild-type mice. We conclude that both bradykinin receptors contribute to the cardioprotective bradykinin-mediated effect of ACE inhibition, not only the B(2)R as believed previously; but, whereas with potentiated bradykinin in the absence of B(1)R, the upregulation of B(2)R is simply insufficient to provide full cardioprotection, in the absence of B(2)R, the upregulated B(1)R actually seems to inflict further tissue damage.
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Affiliation(s)
- Arvi Duka
- Hypertension and Atherosclerosis Section, Boston University School of Medicine, Boston, MA 02118, USA
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10
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Gavras I. The incidentally discovered adrenal mass. N Engl J Med 2007; 356:2005-6. [PMID: 17506163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
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11
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Sun B, Kintsurashvili E, Ona D, Ignjacev-Lazich I, Gavras I, Gavras H. Inhibition of the alpha(1D)-adrenergic receptor gene by RNA interference (RNAi) in rat vascular smooth muscle cells and its effects on other adrenergic receptors. Vascul Pharmacol 2007; 46:367-72. [PMID: 17307398 PMCID: PMC1868522 DOI: 10.1016/j.vph.2007.01.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Revised: 11/06/2006] [Accepted: 01/08/2007] [Indexed: 10/23/2022]
Abstract
Sympathetic-induced vasoconstriction is mediated by various adrenergic receptor (AR) subtypes located on membranes of vascular smooth muscle cells (VSMC) located on the arterial wall, but is mostly attributed to activation of the alpha(1D)-AR. In order to study interaction and cross-talk among AR genes, we induced post-transcriptional silencing of the alpha(1D)-AR gene in cultured VSMC using the RNAi technique. A pSEC neo expression plasmid vector containing a small interfering RNA (siRNA) sequence selected to bind to the targeted mRNA of the alpha(1D)-AR gene was transfected into cultured VSMC from rat aorta. The RNA expression of all AR-subtype genes was assessed by Q-RT-PCR and the alpha(1D) and alpha(2A)-AR proteins quantified by Western blot. In siRNA-transfected cells, the alpha(1D)-AR protein levels decreased by 55%, 69% and 75% at 24 h, 48 h and 72 h, respectively (p<0.03-0.01) with progressive increases in its gene expression by 50%-61% and concurrent increase in alpha(2A)-AR protein peaking at 48 h. Decreases were noted in expression of the alpha(1A), alpha(2A), and beta(3) AR genes. We conclude that post-transcriptional silencing of the alpha(1D)-AR gene leads to significant decrease in receptor protein despite reactive increase in gene expression. However, suppression of one AR leads to reactive changes in other subtypes, indicating that cross-talk among related genes, whose products have overlapping functions, may partly offset anticipated effects in vivo.
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MESH Headings
- Animals
- Aorta, Thoracic/cytology
- Aorta, Thoracic/metabolism
- Cells, Cultured
- Male
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/metabolism
- RNA Interference
- RNA, Messenger/metabolism
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-1/genetics
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Adrenergic, alpha-2/metabolism
- Receptors, Adrenergic, beta-3/metabolism
- Time Factors
- Transfection
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Affiliation(s)
- Bei Sun
- Hypertension and Atherosclerosis Section of the Department of Medicine, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
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12
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Martin LC, Franco RJS, Gavras I, Matsubara BB, Okoshi K, Zanati SG, Caramori JT, Barretti P, Balbi AL, Gavras H. Is 44-Hour Better than 24-Hour Ambulatory Blood Pressure Monitoring in Hemodialysis? Kidney Blood Press Res 2006; 29:273-9. [PMID: 17035712 DOI: 10.1159/000096176] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Accepted: 08/07/2006] [Indexed: 11/19/2022] Open
Abstract
The aim of this study is to evaluate if hemodialysis (HD) patients with similar blood pressure (BP) in the whole inter-HD period could have different target organ lesions and survival if the behavior of BP differs from the first to the second day of the inter-HD period. The present study compares 44-hour ambulatory BP monitoring (ABPM) patterns in 45 HD patients. Three BP patterns emerged: group A (n = 15) had similar BPs throughout (138 +/- 11/88 +/- 12 in the first 22 h vs. 140 +/- 11/87 +/- 12 mm Hg in the second 22-hour period); group B (n = 15) had a significant systolic BP rise from the first to the second period (132 +/- 15/80 +/- 12 vs. 147 +/- 12/86 +/- 13 mm Hg, p < 0.05); group C (n = 15) had significantly higher BPs (p < 0.05) than the other 2 groups throughout the whole inter-HD period, with no significant change between the 2 halves (172 +/- 14/108 +/- 12 vs. 173 +/- 18/109 +/- 14 mm Hg). Ventricular mass and survival during the 30-month follow-up period were statistically significantly better in group A, intermediate in group B and worse in group C. The data suggest that a 44-hour ABPM is more accurate than a 24-hour one in evaluating organ lesion and prognosis in HD patients.
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Affiliation(s)
- L C Martin
- Division of Nephrology, Department of Internal Medicine, Botucatu Medical School, Botucatu, Brazil.
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13
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Cardoso de Carvalho F, Bregagnollo E, Santos Silva V, Brunie A, da Silva Franco RJ, Martin LC, Gavras I, Gavras H. Frequency of coronary artery disease in patients with renal artery stenosis without clinical manifestations of coronary insufficiency. Am J Hypertens 2006; 19:1125-8. [PMID: 17070422 DOI: 10.1016/j.amjhyper.2006.04.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Revised: 04/19/2006] [Accepted: 04/22/2006] [Indexed: 11/25/2022] Open
Abstract
Atherosclerotic renal artery stenosis (RAS) and coronary artery disease (CAD) arise from the same multiple risk factors. The purpose of this study was to assess the frequency of previously undiagnosed CAD in patients with angiographically confirmed RAS, by conducting coronary arteriography in the same setting. Of 57 consecutive patients referred for renal arteriography on clinical grounds during a 14-month period, 28 had no RAS and 6 had RAS, but previously documented CAD. Of the remainder 23 patients, 17 (74%; CI 56%-92%) had both RAS and CAD (7 single vessel, 4 two-vessel, and 7 multivessel disease). The clinical characteristics, such as age, blood pressure (BP) levels, signs of heart failure, were no different between those with and without CAD, although the 4 diabetic patients, the 4 patients with fundoscopic findings of grade III retinopathy, 11 of 14 with peripheral arterial disease, and 7 of 8 patients with prior stroke belonged in the CAD group. None developed complications as a result of the two consecutive procedures. The data suggest that in patients with RAS the frequency of silent CAD is high and cannot be predicted on clinical grounds alone, therefore coronary angiography should be routinely recommended in the same setting.
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Affiliation(s)
- Fábio Cardoso de Carvalho
- Section of Cardiology, Department of Internal Medicine, Botucatu Medical School, Universidade Estadual Paulista, São Paulo, Brazil
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14
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Shenouda SM, Johns C, Kintsurashvili E, Gavras I, Gavras H. Long-term inhibition of the central alpha(2B)-adrenergic receptor gene via recombinant AAV-delivered antisense in hypertensive rats. Am J Hypertens 2006; 19:1135-43. [PMID: 17070424 DOI: 10.1016/j.amjhyper.2006.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 03/30/2006] [Accepted: 04/01/2006] [Indexed: 10/24/2022] Open
Abstract
BACKGROUND Salt-induced hypertension is mediated via the alpha(2B)-adrenergic receptor (AR) subtype. In alpha(2B)-AR gene knockout mice, blood pressure (BP) does not rise with salt loading, and in rats with salt-induced hypertension, BP decreases transiently with antisense (AS) treatment targeting the alpha(2B)-AR gene. The present experiments were designed to explore the possibility of gene transfection in the brain by intracerebroventricular (ICV) delivery of AS-DNA via adeno-associated virus (AAV) to prolong alpha(2B)-AR inhibition and hence reversal of salt-dependent hypertension. METHODS A recombinant AAV (rAAV) vector preparation encoding the alpha(2B)-AS fragment (previously tested in vitro for inhibition of alpha(2B)-AR protein production in cells) and containing green fluorescence protein (GFP) for visualization was injected ICV into subtotally nephrectomized, salt-fed rats. Control rats received rAAV-GFP (n = 8 per group). RESULTS We observed that BP rose from a baseline of 120 +/- 10 to 184 +/- 12 mm Hg. Injection of rAAV-alpha(2B)-AS produced a 35 +/- 12 mm Hg fall in BP, lasting without evidence of diminishing for at least 16 days, whereas rAAV-GFP-injected rats showed a continued rise in BP. Rats treated with rAAV-alpha(2B)-AS treated had a 45% to 65% decrease in alpha(2B)-AR protein levels in key regulatory regions of the brain. Neither group had signs of immunologic response to the virus injection. CONCLUSIONS These results indicate that our construct, when given by ICV means, could reach multiple sites of the central nervous system relevant to BP regulation and could safely inhibit the central alpha(2B)-adrenergic receptor, thereby achieving prolonged reversal of salt-induced hypertension.
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MESH Headings
- Adrenergic alpha-2 Receptor Antagonists
- Animals
- Blotting, Western
- Cells, Cultured
- Central Nervous System/metabolism
- Central Nervous System/pathology
- DNA, Antisense/administration & dosage
- DNA, Antisense/therapeutic use
- Dependovirus/genetics
- Disease Models, Animal
- Gene Expression Regulation
- Genetic Therapy
- Genetic Vectors
- Green Fluorescent Proteins
- Hypertension/therapy
- Immunohistochemistry
- Injections, Intraventricular
- Male
- Mice
- Microscopy, Fluorescence
- Plasmids
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-2/genetics
- Receptors, Adrenergic, alpha-2/metabolism
- Transfection
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Affiliation(s)
- Sherene M Shenouda
- Hypertension and Atherosclerosis Section of the Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
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15
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Abstract
With inhibition or absence of the bradykinin B2 receptor (B2R), B1R is upregulated and assumes some of the hemodynamic properties of B2R, indicating that both participate in the maintenance of normal vasoregulation or to development of hypertension. Herein we further evaluate the role of bradykinin in normal blood pressure (BP) regulation and its relationship with other vasoactive factors by selectively blocking its receptors. Six groups of Wistar rats were treated for 3 wk: one control group with vehicle alone, one with concurrent administration of B1R antagonist R-954 (70 microg x kg(-1) x day(-1)) and B2R antagonist HOE-140 (500 microg x kg(-1) x day(-1)), one with R-954 alone, one with HOE 140 alone, one with concurrent administration of both R-954 and HOE-140 plus the angiotensin antagonist losartan (5 mg x kg(-1) x day(-1)), and one with only losartan. BP was measured continuously by radiotelemetry. Only combined administration of B1R and B2R antagonists produced a significant BP increase from a baseline of 107-119 mmHg at end point, which could be partly prevented by losartan and was not associated with change in catecholamines, suggesting no involvement of the sympathoadrenal system. The impact of blockade of bradykinin on other vasoregulating systems was assessed by evaluating gene expression of different vasoactive factors. There was upregulation of the eNOS, AT1 receptor, PGE2 receptor, and tissue kallikrein genes in cardiac and renal tissues, more pronounced when both bradykinin receptors were blocked; significant downregulation of AT2 receptor gene in renal tissues only; and no consistent changes in B1R and B2R genes in either tissue. The results indicate that both B1R and B2R contribute to the maintenance of normal BP, but one can compensate for inhibition of the other, and the chronic inhibition of both leads to significant upregulation in the genes of related vasoactive systems.
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Affiliation(s)
- Arvi Duka
- Hypertension and Atherosclerosis Section, Department of Medicine, Boston University School of Medicine, 715 Albany St., Boston, MA 02118, USA
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16
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Triantafyllidi H, Kintsurashvili E, Johns C, Gavras I, Gavras H. Central plasmid antisense administration reduces blood pressure inhibiting alpha2B adrenoceptor gene expression in spontaneously hypertensive rats in vivo. Hellenic J Cardiol 2006; 47:144-9. [PMID: 16862820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023] Open
Abstract
INTRODUCTION The involvement of central alpha2B adrenoceptors (AR) in the maintenance of hypertension has been proven by a series of previous experiments, at least in a particular model of nephrogenic salt-induced hypertension. The aim of the present study was to investigate further the role of central alpha2B AR in hypertension by applying antisense technology in another experimental model, the spontaneously hypertensive rat (SHR). METHODS Plasmid antisense DNA against the alpha2B gene was given by intracerebroventricular injection to salt-fed SHRs, while a control group received plasmid alone. RESULTS There was a significant fall in blood pressure, by an average of 31 +/- 12 mmHg, within the first twenty hours after injection in the antisense group. On the first post-injection day the blood pressure fell from 204 +/- 5.3 mmHg to 176.8 +/- 2.9 mmHg (p = 0.02). However, no significant changes in blood pressure were noticed in the plasmid group. Body-weight in both groups remained stable during the experiment. A study of frozen brain sections of SHRs after antisense DNA injection suggested that the nucleus tractus solitarii was one of the expression sites, while there was no histological evidence of tissue disruption. CONCLUSION Central injection of antisense DNA targeting alpha2B mRNA in the genetic model of hypertension of the SHR seems to have a significant hypotensive effect, at least on the first day of injection. The nucleus tractus solitarii seems to be the primary area of action of central alpha2B AR in SHRs.
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Affiliation(s)
- Helen Triantafyllidi
- Hypertension and Atherosclerosis Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
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17
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Abstract
As combinations of drugs from different classes that have synergistic or additive effect and properties to cancel out each others' untoward hemodynamic and metabolic effects become more and more widely used, their use as first-line therapy for the treatment of newly diagnosed hypertensive patients is growing in popularity as well. The possibility to begin therapy with a fixed 2-drug combination may be preferable to starting with monotherapy followed by upward titration and addition of other agents. More and more combinations are coming out on the market and proving their effectiveness in randomized controlled trials and in large multicenter studies. One suggestion is the "polypill," a fixed combination of multiple agents that address various components of the metabolic syndrome and coexisting common risk factors in both high-risk patients with conditions requiring polypharmacy, and in healthy asymptomatic individuals.
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Affiliation(s)
- Talma Rosenthal
- Hypertension Research Unit, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
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18
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Duka A, Schwartz F, Duka I, Johns C, Melista E, Gavras I, Gavras H. A novel gene (Cmya3) induced in the heart by angiotensin II-dependent but not salt-dependent hypertension in mice. Am J Hypertens 2006; 19:275-81. [PMID: 16500513 DOI: 10.1016/j.amjhyper.2005.08.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2005] [Revised: 08/14/2005] [Accepted: 08/29/2005] [Indexed: 10/25/2022] Open
Abstract
OBJECTIVE In previous studies using serial analysis of gene expression for elucidation of the molecular pathways of angiotensin II (Ang II)-induced hypertensive/ischemic cardiomyopathy in mice, we found that a hitherto unknown transcript, designated initially as 2310008C07Rik, an unknown expressed sequence tag (EST), was highly significantly upregulated in myocardial tissue. The current experiments were designed to further characterize this gene and to evaluate its expression in various types of hypertension. METHODS Mice rendered hypertensive by Ang II infused intravenously at 30 ng/min for 6 h or by osmotic minipump at 0.9 mug/h for 7 or 14 days, were compared to saline-infused normotensive controls and to mice with hypertension induced by subtotal nephrectomy and 1% saline as drinking water. At end point, mice were euthanized, their tissues processed for gene expression analysis, and results were confirmed by ribonuclease protection assay. RESULTS The Ang II-infused mice developed systolic blood pressure (BP) of 134 +/- 7, 158 +/- 13, and 149 +/- 15 mm Hg at 6 h, 7 days, and 14 days, respectively, compared to 102 +/- 9, 110 +/- 8, and 114 +/- 7 mm Hg in their respective controls and subtotally nephrectomized salt-fed mice had end point blood pressure of 153 +/- 5 v 112 +/- 7 mm Hg in controls. Through sequencing and expression analysis we found that the unknown transcript is part of the cardiomyopathy associated 3 (Cmya3) gene, being overexpressed in Ang II-induced but not salt-induced hypertension. CONCLUSIONS The highly expressed 2310008C07Rik EST was found to be part of Cmya3 and its upregulation is due to Ang II-induced myocardial damage and not to BP elevation per se.
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Affiliation(s)
- Arvi Duka
- Department of Medicine, Hypertension and Atherosclerosis Section, Boston University School of Medicine, Boston, Massachusetts, USA
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19
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Ignjacev-Lazich I, Kintsurashvili E, Johns C, Vitseva O, Duka A, Shenouda S, Gavras I, Gavras H. Angiotensin-converting enzyme regulates bradykinin receptor gene expression. Am J Physiol Heart Circ Physiol 2005; 289:H1814-20. [PMID: 16219810 DOI: 10.1152/ajpheart.00581.2005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The angiotensin-converting enzyme (ACE) is a membrane-bound peptidyl dipeptidase known to act on a variety of peptide substrates in the extracellular space. Its most notable functions are the formation of angiotensin II and the degradation of bradykinin. In the current experiments, we found that exogenous ACE added to vascular smooth muscle cell culture strongly induces and upregulates the genes of bradykinin receptors B1 and B2. This transcriptional regulatory property of ACE was shown to be unrelated to its known enzymatic properties. Indeed, ACE at 3.75 microg/ml added in the culture medium of vascular smooth muscle cells was found to cause marked upregulation of the mRNA expression of the genes for the B1 and B2 receptors of bradykinin by 22- and 11-fold, respectively. This phenomenon was not altered by the addition of specific angiotensin II antagonists for the AT1 or AT2 receptors. Moreover, the ACE inhibitor captopril, which inhibited ACE enzymatic activity, did not block its effect at the bradykinin receptor gene transcription level. Expression of both receptor genes was completely abolished by actinomycin D. Furthermore, transcriptional upregulation was inhibited by curcumin, suggesting involvement of different transcriptional factors in this phenomenon. Electrophoretic mobility shift assay revealed increase in NF-kappaB and activator protein-1 protein binding for consensus sequences, between ACE-treated cells versus untreated cells. The data indicate a novel biological function of the ACE unrelated to its well-known enzymatic function as a peptidyl dipeptidase.
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MESH Headings
- Angiotensin II Type 1 Receptor Blockers/pharmacology
- Animals
- Blotting, Western
- Cell Nucleus/chemistry
- Cells, Cultured
- Cyclic AMP/metabolism
- Electrophoretic Mobility Shift Assay
- Gene Expression Regulation/physiology
- Male
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- NF-kappa B/metabolism
- Peptidyl-Dipeptidase A/physiology
- RNA/biosynthesis
- RNA/isolation & purification
- Rats
- Rats, Wistar
- Receptor, Bradykinin B1/biosynthesis
- Receptor, Bradykinin B1/genetics
- Receptor, Bradykinin B2/biosynthesis
- Receptor, Bradykinin B2/genetics
- Receptors, Bradykinin/biosynthesis
- Receptors, Bradykinin/genetics
- Transcription Factor AP-1/metabolism
- Up-Regulation
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Affiliation(s)
- Ivana Ignjacev-Lazich
- Hypertension & Atherosclerosis Section, Boston Univ. School of Medicine, 715 Albany St., Boston, MA, USA
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20
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Abstract
Aging is a major risk factor for the development of vascular diseases, such as hypertension and atherosclerosis, that leads to end organ damage and especially heart failure. Bradykinin has been demonstrated to have a cardioprotective role by affecting metabolic processes and tissue perfusion under conditions of myocardial ischemia. Its actions are exerted via the bradykinin B1- and B2-type receptors (B1Rs and B2Rs), but the functional status of these receptors during the aging process is poorly understood. This study aims to investigate whether changes in B1R and B2R gene and protein expression in rat heart are associated with the age-related alterations of cardiac structure and function. Using real-time PCR, we found that B1R mRNA expression increased 2.9-fold in hearts of older rats (24 mo of age) compared with younger rats (3 mo of age), whereas B2R gene expression remained unchanged. Western blot analysis showed that expression of B2R at the protein level is approximately twofold higher in young rats compared with old rats, whereas the B1R protein is approximately twofold higher in old rats compared with young rats. The present results provide clear functional and molecular evidence that indicate age-related changes of bradykinin B1Rs and B2Rs in heart. Because the cardioprotective actions of bradykinin are physiologically mediated via the B2Rs, whereas the B1Rs become induced by tissue damage, these results suggest that age-related decreases in B2R protein levels may leave the heart vulnerable to ischemic damage, and increases in B1R expression and activity may represent a compensatory reaction in aging hearts.
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Affiliation(s)
- Ekaterina Kintsurashvili
- Hypertension and Atherosclerosis Section, Boston Univ. School of Medicine, 715 Albany St., Boston, MA 02118, USA
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21
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22
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Gavras I, Gavras H. ACE Inhibitor Trials: Effects in Hypertension. Hypertension 2005. [DOI: 10.1016/b978-0-7216-0258-5.50125-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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23
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24
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Manolis AJ, Iraklianou S, Pittaras A, Zaris M, Tsioufis K, Psaltiras G, Psomali D, Foussas S, Gavras I, Gavras H. Arterial compliance changes in diabetic normotensive patients after angiotensin-converting enzyme inhibition therapy. Am J Hypertens 2005; 18:18-22. [PMID: 15691612 DOI: 10.1016/j.amjhyper.2004.08.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2004] [Revised: 08/18/2004] [Accepted: 08/19/2004] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Diabetes mellitus (DM) is known to cause increased arterial wall stiffness and increased cardiovascular risk, even in the absence of hypertension. This study was designed to investigate whether use of an angiotensin-converting enzyme (ACE) inhibitor may improve arterial stiffness in normotensive diabetics, using pulse wave velocity (PWV) as a surrogate marker. METHODS We studied 42 patients (26 with type 2 DM, aged 56.5 +/- 9 years, 16 with type 1 DM, aged 41.5 +/- 11 years) by measuring PWV at baseline (compared to 15 age- and gender-matched normal subjects) and after 6 months of treatment with perindopril (4 mg/d). RESULTS At baseline, PWV was significantly higher in DM patients versus controls (13.09 +/- 2.59 v 9.5 +/- 1.6 m/sec, respectively, P < .001). After 6 months, PWV decreased significantly to 11.68 +/- 3.08 m/sec (P < .003) for the whole DM group. However, the results were driven by the change in the younger type 1 DM (from 12.59 +/- 1.59 to 10.35 +/- 2.21 m/sec, P < .001), whereas in the type 2 DM it was insignificant (from 13.37 +/- 3.0 to 12.42 +/- 3.28 m/sec). Blood pressure and other hemodynamic and biochemical parameters remained unchanged. CONCLUSIONS The results demonstrate that ACE inhibition can improve arterial elasticity and hence risk of cardiovascular complications even in normotensive diabetics. This short treatment was effective only in younger patients with type 1 diabetes, suggesting that early initiation of therapy before the onset of advanced structural alterations is likely to be more cardioprotective.
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25
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Martin LC, Franco RJS, Gavras I, Matsubara BB, Garcia S, Caramori JT, Barretti BB, Balbi AL, Barsanti R, Padovani C, Gavras H. Association between hypervolemia and ventricular hypertrophy in hemodialysis patients. Am J Hypertens 2004; 17:1163-9. [PMID: 15607624 DOI: 10.1016/j.amjhyper.2004.07.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2004] [Revised: 06/18/2004] [Accepted: 07/21/2004] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND Left ventricular hypertrophy (LVH) is a well-known predictor of cardiovascular mortality in patients who have end-stage renal disease and are maintained on hemodialysis (HD), and LVH is not always correlated with the severity of hypertension in these patients. The purpose of this study was to investigate the role of other factors contributing to LVH. METHODS A total of 50 patients with HD were classified in three groups according to whether their LV mass index (LVMI) was higher than (n = 15), equal to (n = 20), or lower than (n = 15) that predicted by a formula based on their ambulatory blood pressure monitoring (ABPM). RESULTS Subjects with higher LVMI than predicted had significantly greater inter-HD weight gain (3.4 +/- 0.8 v 2.7 +/- 0.8 and 2.6 +/- 05 kg, respectively, in the other two groups, P < .05), and subjects with lower LVMI than predicted had a tendency toward a more pronounced nocturnal dipping pattern of BP (P = .07 v the other two groups), although daytime and night-time average BP levels did not differ between groups. All other clinical and laboratory parameters were similar among the three groups except higher cardiac output and various indices of LVH, which were more pronounced in the group with higher LVMI by ABPM. This group had also the lowest survival rate over the 2 to 3 years of follow-up, with five deaths versus two in each of the other two groups. CONCLUSIONS The data suggest that correct management of inter-HD weight gain by nutritional counseling and shorter inter-HD intervals may prevent LVH and improve survival independently of BP control.
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Affiliation(s)
- L C Martin
- Division of Nephrology, Department of Internal Medicine, Botucatu Medical School, Botucatu, Universidade Estadual Paulista, São Paulo, Brazil
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26
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Abstract
With the cut-off point between "normal" and "high" blood pressure (BP) being pushed increasingly downward, especially for patients with multiple cardiovascular risk factors, most hypertensives need more than one antihypertensive agent to reach their target BP. In this article, we examine the rationale for combining drugs from different classes that have synergistic or additive effects and properties that might offset one another's adverse hemodynamic and/or metabolic reactions. We suggest circumstances in which the initiation of therapy with a fixed two-drug combination might be preferable to the usual practice of starting with monotherapy followed by upward titration and addition of other agents, and we briefly review the existing fixed drug combinations. We end with the intriguing and provocative notion of the future "polypill," a fixed combination of agents addressing various components of the metabolic syndrome as well as other coexisting common risk factors in both high-risk patients with conditions requiring polypharmacy and in healthy, asymptomatic individuals.
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Affiliation(s)
- Irene Gavras
- Hypertension and Atherosclerosis Section, Boston University School of Medicine, 715 Albany Street, W508, Boston, MA 02118, USA.
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27
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Voudris V, Avramides D, Gatzov P, Malakos J, Skoularigis J, Manolis A, Gavras H, Gavras I, Cokkinos DV. The effect of rapid decreases of blood pressure by different mechanisms on coronary flow and flow reserve in normal coronary arteries. Am J Hypertens 2003; 16:1000-5. [PMID: 14643572 DOI: 10.1016/j.amjhyper.2003.07.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND Changes in mean blood pressure (MBP) alter coronary blood flow (CBF). We evaluated the acute effects of three hypotensive medications on CBF parameters in angiographically normal coronary arteries. METHODS We performed CBF measurements using the Doppler wire at rest and during hyperemia produced by intracoronary adenosine (18 microg) as follows: 1) in the normal left circumflex coronary artery in 20 patients with coronary artery disease (measurements were performed without drugs, and after intravenous infusion of nitroprusside [0.5 to 2 microg/kg/min] and nitroglycerin [10 to 90 microg/min]; drugs were titrated to decrease MBP 20% to 25% below the control values, and heart rate was held constant using right atrial pacing); and 2) in the normal left anterior descending coronary artery in 19 patients without coronary artery disease (measurements were performed before and after intravenous clonidine infusion [150 microg in 5 min]; time-averaged peak velocity [APV], CBF, and coronary flow reserve [CFR] were measured). RESULTS Similar decreases in MBP were obtained in the two patient groups. Lumen diameter at the site of Doppler measurements increased after all medications (P <.005), whereas CBF did not change significantly. The CFR decreased after nitroprusside (1.79 +/- 0.48 v 2.54 +/- 0.45, P=.000), did not change significantly after nitroglycerin (2.74 +/- 0.43 v 2.54 +/- 0.45, P =.097), and increased after clonidine (3.12 +/- 0.70 v 2.76 +/- 0.75, P =.006). CONCLUSIONS In normal coronary arteries the infusion of three hypotensive medications to produce the same decreases in MBP is associated with different effects on CFR (increase with clonidine, decrease with nitroprusside, and no change with nitroglycerin).
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Affiliation(s)
- Vassilis Voudris
- 1st Cardiology Department, Onassis Cardiac Surgery Center, Athens, Greece.
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28
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Abstract
Bradykinin normally exerts its vasodilatory effect via the B
2
receptor (B
2
R), but in this receptor’s absence, the B
1
receptor becomes expressed and activated. To explore the mechanism of B
1
R-mediated vasodilation, 8 groups of B
2
R gene–knockout mice received a 2-week infusion of a B
1
R antagonist (300 μg · kg
−1
· d
−1
) or vehicle (groups 1 and 2), B
1
R antagonist or vehicle plus NO inhibition with
Nω
-nitro-
l
-arginine methyl ester (groups 3 and 4), B
1
R antagonist or vehicle plus cyclooxygenase inhibition with indomethacin (groups 5 and 6), or B
1
R antagonist or vehicle plus blockade of vasoconstricting prostaglandin (PG) H
2
and thromboxane A
2
(TxA
2
) with SQ29548 (groups 7 and 8). The B
1
R antagonist produced significant (
P
<0.05) blood pressure increases of 17.7±3.1 mm Hg in group 1 and 10.4±3 mm Hg in group 3, whereas their vehicle-treated respective control groups 2 and 4 had no significant blood pressure changes. Indomethacin abolished the capacity of the B
1
R antagonist to raise blood pressure, as did blockade of the receptors of PGH
2
and TxA
2
. Injection with the B
1
R agonist produced a hypotensive response (12±1.3 mm Hg), which was further accentuated by TxA
2
blockade (21.7±4.1 mm Hg). Analysis of B
1
R gene expression by reverse transcription–polymerase chain reaction (PCR) in cardiac and renal tissues revealed marked expression at baseline, with further upregulation by 1.5- to 2-fold after various manipulations. Expression of the TxA
2
receptor gene in renal tissue by quantitative real-time PCR was significantly lower in mice treated with the B
1
R antagonist, consistent with increased levels of agonist for this receptor. The data confirm that the B
1
R becomes markedly expressed in the absence of B
2
R and suggest that it contributes to vasodilation by inhibiting a vasoconstricting product of the arachidonic acid cascade acting via the PGH
2
/TxA
2
receptor.
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MESH Headings
- Animals
- Blood Pressure/drug effects
- Bradykinin B1 Receptor Antagonists
- Bridged Bicyclo Compounds, Heterocyclic
- Cyclooxygenase Inhibitors/pharmacology
- Enzyme Inhibitors/pharmacology
- Fatty Acids, Unsaturated
- Hydrazines/pharmacology
- Indomethacin/pharmacology
- Mice
- Mice, Knockout
- NG-Nitroarginine Methyl Ester/pharmacology
- Nitric Oxide Synthase/antagonists & inhibitors
- RNA, Messenger/metabolism
- Receptor, Bradykinin B1/genetics
- Receptor, Bradykinin B1/physiology
- Receptor, Bradykinin B2/genetics
- Receptor, Bradykinin B2/physiology
- Receptors, Thromboxane A2, Prostaglandin H2/antagonists & inhibitors
- Vasodilation
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Affiliation(s)
- Irena Duka
- Hypertension and Atherosclerosis Section of the Department of Medicine, Boston University School of Medicine, 715 Albany St, Boston, Mass 02118, USA
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29
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Kintsurashvili E, Johns C, Ignjacev I, Gavras I, Gavras H. Central alpha2B-adrenergic receptor antisense in plasmid vector prolongs reversal of salt-dependent hypertension. J Hypertens 2003; 21:961-7. [PMID: 12714871 DOI: 10.1097/00004872-200305000-00021] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Previous studies have shown that a fully functional alpha(2B)-adrenergic receptor (AR) is necessary for the development of salt-induced hypertension. The current studies were designed to explore the effect of prolonged inhibition of central alpha(2B)-AR gene expression by antisense (AS) DNA on this hypertension. METHODS We developed a plasmid vector driven by a cytomegalovirus promoter, containing a green fluorescent protein reporter gene and AS for rat alpha(2B)-AR protein. Subtotally nephrectomized, salt-loaded hypertensive rats received intracerebroventricular injection of 500 microg of either the AS plasmid (n = 9) or sense plasmid (containing cDNA for alpha(2B)-AR), as control (n = 7). RESULTS The AS injection produced a fall in SBP from 201 +/- 4 to 171 +/- 5 mmHg within 12 h. The level of BP in the 3 days post-injection was 174 +/- 6, 181 +/- 4 and 184 +/- 6 mmHg on day 1, day 2 and day 3, respectively (P < 0.05), and returned gradually towards baseline in subsequent days, although it remained significantly lower for the 8 days of observation. The control sense plasmid injections produced no significant changes in blood pressure (BP). Neither group had histological evidence of neural tissue disruption. CONCLUSIONS These results indicate that protracted translational inhibition of the alpha(2B)-AR gene in the central nervous system can be obtained by AS DNA delivered via plasmid vector and lead to decreased generation of alpha(2B)-AR protein, which can partly reverse salt-induced hypertension for several days.
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MESH Headings
- Animals
- Blood Pressure/drug effects
- Blood Pressure/physiology
- Cells, Cultured
- Circadian Rhythm/drug effects
- Circadian Rhythm/physiology
- Disease Models, Animal
- Genetic Vectors/pharmacology
- Green Fluorescent Proteins
- Hypertension/metabolism
- Hypertension/physiopathology
- Indicators and Reagents
- Injections, Intraventricular
- Luminescent Proteins/biosynthesis
- Luminescent Proteins/drug effects
- Male
- Models, Cardiovascular
- Oligodeoxyribonucleotides, Antisense/pharmacology
- Plasmids/pharmacology
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-2/drug effects
- Receptors, Adrenergic, alpha-2/metabolism
- Receptors, Virus/drug effects
- Receptors, Virus/metabolism
- Systole/drug effects
- Systole/physiology
- Time Factors
- Transfection
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30
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Gavras I, Gavras H. Are patients who develop angioedema with ACE inhibition at risk of the same problem with AT1 receptor blockers? Arch Intern Med 2003; 163:240-1. [PMID: 12546617 DOI: 10.1001/archinte.163.2.240] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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31
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Gavras I. Prevention of recurrent stones in idiopathic hypercalciuria. N Engl J Med 2002; 346:1667-9. [PMID: 12030261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
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32
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Abstract
A renin-angiotensin level that is inappropriately high for the systemic blood pressure and the state of sodium balance is now recognized to be one of the modifiable cardiovascular risk factors. Angiotensin acts both as a circulating hormone and as a locally acting paracrine/autocrine/intracrine factor. The adverse effects of angiotensin on the heart include the mechanical results of elevated resistance to the pumping function of the myocardium, as well as the effects of neurohumoral abnormalities on various cardiac structures. In addition, cardiac damage follows acute ischaemic injury or chronic energy starvation due to coronary artery disease, attributable to either mechanical obstruction (atherosclerotic and/or thrombotic) or functional stenosis (vasospasm). Activation of the renin-angiotensin system has several haemodynamic and humoral consequences, all of which may damage the myocardium. These include acute myocardial ischaemia, left-ventricular hypertrophy, arrhythmias, alterations in the coagulation-fibrinolysis equilibrium, increased oxidative stress, and pro-inflammatory activity. A brief review of some of the mechanisms by which activation of the renin-angiotensin system can inflict damage on the heart is presented.
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Affiliation(s)
- I Gavras
- Hypertension and Atherosclerosis Section, Department of Medicine, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
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33
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Monteagudo PT, Gavras H, Gavras I, Kohlmann O, Ribeiro AB, Zanella MT. Role of vasopressin in 24-hour blood pressure regulation in diabetic patients with autonomic neuropathy. Am J Hypertens 2002; 15:42-7. [PMID: 11824859 DOI: 10.1016/s0895-7061(01)02229-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
To evaluate the role of vasopressin (AVP) on blood pressure (BP) in diabetic patients with autonomic neuropathy (AN), 10 patients were studied on a fixed sodium and potassium diet. On days 4 and 7, a 24-h BP monitoring, as well as blood and urine samples for sodium, potassium, creatinine, and osmolality determinations were obtained for every 4-h period; either placebo or an AVP-V1-antagonist (d(CH2)5Tyr(me)AVP; 0.5 mg; AVPi) were given iv at 1 PM. On placebo, systolic BP (SBP) showed a progressive elevation during the day, declining after 12 PM (8 AM to 12 AM 122+/-9; 12 AM to 4 PM 125+/-11; 4 PM to 8 PM 134+/-14; 8 PM to 12 PM 136+/-14; 12 PM to 8 AM 131+/-17 mm Hg). On AVPi this rise in SBP was blunted: 8 AM to 12 AM 125+/-122; 12 AM to 4 PM 121+/-21; 4 PM to 8 PM 126+/-16; 8 PM to 12 PM 129+/-14; 12 PM to 8 AM 124+/-12 mm Hg. Creatinine clearance and diureses were greater during the night, both with placebo and AVPi. Plasma osmolality did not change on either day, although serum sodium decreased after AVPi, reaching the lowest values at 4 PM to 8 PM period (137+/-4.7 v 131+/-3.8 mEq/L; P < .05). With placebo, fractional excretion of sodium (FENa) increased from 0.43%+/-0.32% during 12 h of orthostasis to 0.92%+/-1.05% during 12 h of recumbency (P < .02). With AVPi, the FENa on orthostasis did not differ from that with placebo, although BP values were lower and did not increase with recumbency (0.58+/-0.57 v 0.73%+/-0.49%; NS). In conclusion, our results show that in diabetic patients with AN, vasopressin participates in BP control by stimulating vascular and renal V1 receptors, which results in vasoconstriction and sodium reabsorption.
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Affiliation(s)
- Patricia T Monteagudo
- Endocrinology Division, Department of Medicine, Universidade Federal de São Paulo, São Paulo, Brazil
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34
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Abstract
The biological actions of bradykinin (BK) are attributed to its B(2) type receptor (B(2)R), whereas the B(1)R is constitutively absent, inducible by inflammation and toxins. Previous studies in B(2)R gene knockout mice showed that the B(1)R is overexpressed, is further upregulated by hypertensive maneuvers, and assumes some of the hemodynamic functions of the B(2)R. The current experiments were designed to further clarify the metabolic function of the B(2)R and to explore whether the upregulated B(1)R can also assume the metabolic function of the missing B(2)R. One group of B(2)R-/- mice (n=9) and one of B(2)R+/+ controls (n=8) were treated for 3 days with captopril (which produced a similar blood pressure-lowering response in both groups) and studied with the hyperinsulinemic euglycemic clamp. The knockout mice had fasting and steady-state blood glucose levels similar to those of the wild-type mice but a had tendency to higher fasting insulin levels (at 27.8+/-5.2 versus 18+/-2.9 mU/L, respectively). However, they had significantly higher steady-state insulin levels (749+/-127.2 versus 429.1+/-31.5 mU/L, P<0.05) and a significantly lower glucose uptake rate (31+/-2.4 versus 41+/-2.3 mg/kg per minute, P<0.05) and insulin sensitivity index (4.6+/-0.9 versus 10+/-0.7 P<0.001). Analysis of B(1)R and B(2)R gene expression by reverse transcription-polymerase chain reaction in cardiac muscle, skeletal muscle, and adipose tissues revealed significantly higher B(1)R mRNA level in the knockouts versus wild-type (P<0.05) at baseline and a further significant upregulation in mRNA by 1.8- to 3.2-fold (P<0.05) after insulin infusion. We conclude that absence of B(2)R confers a state of insulin resistance because it results in impaired insulin-dependent glucose transport; this is probably a direct B(2)R effect because, unlike the hemodynamic autacoid-mediated effects, it cannot be assumed by the upregulated B(1)R.
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Affiliation(s)
- I Duka
- Hypertension and Atherosclerosis Section of the Department of Medicine, Boston University School of Medicine, MA 02118, USA
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35
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Abstract
This is a brief overview of experimental and clinical studies exploring the hemodynamic functions of the alpha2A and alpha2B adrenergic receptor (AR) subtypes in animals submitted to genetic manipulations or gene treatment, as well as the clinical effects of central sympathetic suppression with the alpha2-AR agonist clonidine in patients with ischemic heart disease and/or heart failure. The animal experiments have led us to conclude that the sympathetic outflow is regulated by activation of the presynaptic alpha2A-AR subtype, which is the predominant alpha2-AR subtype in the central nervous system and exerts a sympathoinhibitory (hypotensive) action; on the contrary, activation of the central alpha2B-AR elicits a sympathoexcitatory response (such as seen in salt-induced hypertension, which requires functionally intact alpha2B-AR). Since there are no selective pharmacologic agents yet capable of discriminating among alpha2-AR subtypes, clinical studies utilize clonidine, the central sympathetic suppressant effect of which has been used for 35 years to treat hypertension. In small clinical trials, clonidine was used successfully for treatment of acute or chronic heart failure, acute myocardial infarct or hypertensive cardiomyopathy with subclinical diastolic dysfunction. We speculate that future development of agents capable of selectively activating the alpha2A-AR or blocking the alpha2B-AR may further improve our capability to treat hypertension, ischemic heart disease and heart failure.
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Affiliation(s)
- I Gavras
- Hypertension and Atherosclerosis Section of the Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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36
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Kintsurashvili E, Gavras I, Johns C, Gavras H. Effects of antisense oligodeoxynucleotide targeting of the alpha(2B)-adrenergic receptor messenger RNA in the central nervous system. Hypertension 2001; 38:1075-80. [PMID: 11711500 DOI: 10.1161/hy1101.093426] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The results of previous studies with genetically engineered mice have suggested that an intact central alpha(2B)-adrenergic receptor (alpha(2B)-AR) subtype mediates the development and maintenance of salt-induced hypertension. In the present study, we sought to further define the role of this receptor by injecting antisense oligodeoxynucleotides (AS-ODNs), targeting a selected sequence of the alpha(2B)-AR mRNA, into the lateral cerebral ventricle of rats that had undergone prior subtotal nephrectomy and dietary salt loading. Cell culture studies showed that these AS-ODNs could block alpha(2B)-AR protein generation. Before AS-ODN injection, blood pressure (BP) averaged 133+/-5 mm Hg during the daytime and rose to 165+/-4 mm Hg during the nighttime activity hours (P<0.001 versus baseline average of 120+/-2 mm Hg). The injection of AS-ODNs during the early afternoon prevented the BP rise and was associated with a significant fall in heart rate (from 385+/-12 to 306+/-15 bpm, P<0.05) and symptoms of sedation that lasted for several hours, with a peak at 3 to 6 hours and full recovery by 24 hours. At that time, a second injection produced identical effects in all rats (n=9). Control rats (n=10) that received scrambled ODN injections had no changes in BP or heart rate patterns, and neither group had evidence of neurotoxicity, indicating that these effects are specifically due to translational inhibition of central alpha(2B)-AR. We conclude that a fully functional central alpha(2B)-AR is necessary for the induction of salt-dependent hypertension.
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MESH Headings
- Animals
- Behavior, Animal
- Blood Pressure
- Brain/drug effects
- Brain/metabolism
- Fluorescein-5-isothiocyanate/chemistry
- Fluorescent Dyes/chemistry
- Hypertension/etiology
- Hypertension/metabolism
- Hypertension/physiopathology
- Male
- Oligodeoxyribonucleotides, Antisense/pharmacokinetics
- Oligodeoxyribonucleotides, Antisense/pharmacology
- RNA, Messenger/biosynthesis
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-2/biosynthesis
- Receptors, Adrenergic, alpha-2/genetics
- Tumor Cells, Cultured
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Affiliation(s)
- E Kintsurashvili
- Hypertension and Atherosclerosis Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
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37
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Kintsurashvili E, Duka I, Gavras I, Johns C, Farmakiotis D, Gavras H. Effects of ANG II on bradykinin receptor gene expression in cardiomyocytes and vascular smooth muscle cells. Am J Physiol Heart Circ Physiol 2001; 281:H1778-83. [PMID: 11557571 DOI: 10.1152/ajpheart.2001.281.4.h1778] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bradykinin has vasodilatory and tissue-protective effects exerted via its B(2) type receptor, whereas the B(1) receptor is constitutively absent but inducible by inflammation and toxins. In previous studies, we found that B(2) receptor gene knockout mice exhibit overexpression of the B(1) receptor, which assumes a vasodilatory function and is further upgraded in renovascular hypertension. The present study was designed to explore the effects of excess angiotensin II (ANG II) on B(1) receptor and B(2) receptor gene expression in mouse cardiomyocytes and rat vascular smooth muscle cells (VSMC) in vivo (after a 3-day infusion of 30 ng/min ANG II in 11 wild-type and in 13 genetically engineered mice with deleted B(2) receptor gene) and in vitro (ANG II added in rat VSMC culture in the presence or absence of AT(1) or AT(2) receptor antagonist). Expression of B(1) and B(2) receptor mRNA was assessed by reverse transcriptase-polymerase chain reaction. ANG II infusion caused upregulation by 30% of the already significantly overexpressed B(1) receptors in cardiomyocytes of the B(2) receptor gene knockout mice, but in the wild-type mice it upregulated only the B(2) receptor mRNA by 47%. The addition of ANG II in VSMC culture produced a time-dependent induction of B(1) and upregulation of B(2) receptor gene expression, maximal at 3 h (by fivefold), declining almost to baseline by 24 h. The addition of losartan completely blocked this effect, whereas the AT(2) blocker PD-123319 made no difference, indicating that this is an AT(1)-mediated effect of ANG II. The data indicate that excess ANG II in subpressor doses in vivo upregulates expression of the B(2) receptor, but in its absence, the already overexpressed B(1) receptor is further upregulated, evidently assuming a counterregulatory response; in vitro, it transiently upregulates both bradykinin receptors.
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MESH Headings
- Angiotensin II/pharmacology
- Animals
- Cells, Cultured
- Gene Expression/drug effects
- Heart/drug effects
- Heart/physiology
- Hemodynamics/drug effects
- Male
- Mice
- Mice, Knockout/genetics
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Myocardium/cytology
- Myocardium/metabolism
- RNA, Messenger/metabolism
- Rats
- Rats, Wistar
- Receptor, Bradykinin B1
- Receptor, Bradykinin B2
- Receptors, Bradykinin/genetics
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Affiliation(s)
- E Kintsurashvili
- Hypertension and Atherosclerosis Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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38
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Stefanadis C, Manolis A, Dernellis J, Tsioufis C, Tsiamis E, Gavras I, Gavras H, Toutouzas P. Acute effect of clonidine on left ventricular pressure-volume relation in hypertensive patients with diastolic heart dysfunction. J Hum Hypertens 2001; 15:635-42. [PMID: 11550110 DOI: 10.1038/sj.jhh.1001243] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2001] [Revised: 03/20/2001] [Accepted: 04/30/2001] [Indexed: 11/08/2022]
Abstract
We sought to assess the haemodynamic effects of clonidine on left ventricular (LV) pressure-volume relation in patients with diastolic heart dysfunction due to essential hypertension. Towards this end, simultaneous recordings of LV volume (acoustic quantification) and LV pressure (micromanometer) were obtained in 10 such patients before and after drug administration and compared to baseline findings on 10 matched normal controls. The following measurements and calculations were obtained: maximal positive and negative first derivative of LV pressure (peak +dP/dt and peak -dP/dt, respectively), LV minimal and end-diastolic pressure, peak systolic blood pressure, time constant of relaxation (TAU), LV stroke work and LV stiffness constant. The two invasive indexes, LV stiffness constant and TAU classified 10/10 patients as having abnormal LV diastolic function compared with 7/10 patients so classified by Doppler studies. Central sympathetic suppression by a single oral dose of clonidine 0.125 mg in these patients resulted within 60 min in a decrease of heart rate and mean arterial pressure as well as a significant improvement of LV diastolic function indexes. Specifically, the LV stiffness constant (ml(-1)), in normal subjects was 0.0028 vs 0.0152 (P < 0.001) in hypertensive subjects at baseline, vs 0.0053 in hypertensive after clonidine (P < 0.001 vs baseline). Likewise, the E/A ratio, was 1.08 in normal subjects vs 0.88 (P < 0.0001) in hypertensives at baseline, vs 1.28 in hypertensives after clonidine (P < 0.0001 vs baseline). With clonidine the diastolic portion of the pressure-volume curve was displaced downward. In conclusion, clonidine can improve diastolic dysfunction without depressing systolic LV performance. The improvement may be attributable in part to withdrawal of direct sympathetic influence on the myocardium and in part to the indirect effect of systemic, pulmonary and coronary artery relaxation.
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Affiliation(s)
- C Stefanadis
- Hippokration Hospital, Department of Cardiology, University of Athens, Greece
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39
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40
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DeStefano AL, Gavras H, Heard-Costa N, Bursztyn M, Manolis A, Farrer LA, Baldwin CT, Gavras I, Schwartz F. Maternal component in the familial aggregation of hypertension. Clin Genet 2001; 60:13-21. [PMID: 11531965 DOI: 10.1034/j.1399-0004.2001.600103.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
To assess maternal versus paternal contributions to the familial aggregation of hypertension, we examined family history data from 344 hypertensive probands (69 African American, 153 US Caucasian, 122 Greek Caucasian) ascertained without respect to parental hypertension status. The proportion of hypertensive mothers (81.7, 65.0 and 84.8% for African Americans, US Caucasians and Greek Caucasians, respectively) of these probands was significantly greater than the proportion of hypertensive fathers (50.0, 44.9 and 48.3%, respectively) in all three ethnic groups. The lifetime risk of hypertension was significantly greater for mothers compared with fathers of these hypertensive probands (p<0.001). Examination of the proband's siblings indicated that maternal history of hypertension was associated with greater lifetime risk for hypertension than paternal history (p<0.01). In conclusion, we observe a consistent maternal component in the inheritance of hypertension. Although we cannot separate a maternal genetic from epigenetic or environmental effect, our findings suggest that genetic research should include studies of the mitochondrial as well as nuclear genome. Furthermore, when assessing a patient's risk for hypertension, particular attention should be paid to the maternal family history.
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Affiliation(s)
- A L DeStefano
- Department of Neurology, Boston University School of Medicine, Boston, MA 02118, USA
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41
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Abstract
This is a brief review of a series of experiments conducted over the past two decades, exploring the role of the alpha2-adrenergic receptors (alpha2-AR) in salt-induced hypertension. The data suggest that salt loading alters the activity of central alpha2-AR, resulting in a hypertensive hyperadrenergic state. Studies to separate the role of each alpha2-AR subtype (alpha2A, alpha2B, and alpha2C) have used genetically engineered mice with disrupted genes for each subtype, or gene treatment in rats with antisense-oligodeoxynucleotides targeting a specific gene sequence. Taken together, the results of these studies indicate that the alpha2A-AR is centrally predominant and exerts a tonic sympathoinhibitory function, whereas peripherally it has a vasoconstrictive effect; the alpha2B-AR is responsible for the central hypertensive sympathoexcitatory response to salt, but is not expressed on vascular wall structures; and the alpha2C-AR seems to have no hemodynamic function.
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Affiliation(s)
- I Gavras
- Department of Medicine, Boston University School of Medicine, Massachusetts 02118, USA.
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42
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Abstract
The B(1) type receptor of bradykinin (Bk B(1)R) is believed to be physiologically inert but highly inducible by inflammatory mediators and tissue damage. To explore the potential participation of the Bk B(1)R in blood pressure (BP) regulation, we studied mice with deleted Bk B(2)R gene with induced experimental hypertension, either salt-dependent (subtotal nephrectomy with 0.5% NaCl as drinking water) or renin/angiotensin-dependent (renovascular 2-kidney-1-clip). Compared with the wild-type controls, the B(2)R gene knockout mice had a higher baseline BP (109.7+/-1.1 versus 101.1+/-1.3 mm Hg, P:=0.002), developed salt-induced hypertension faster (in 19.3+/-2.3 versus 27.7+/-2.4 days, P:=0.024), and had a more severe end point BP (148+/-3.7 versus 133+/-3.1 mm Hg, P:<0.05). On the contrary, renovascular hypertension developed to the same extent (149.7+/-4.3 versus 148+/-3.6 mm Hg) and in the same time frame (14+/-2.2 versus 14+/-2.1 days). A bolus infusion of a selective B(1)R antagonist at baseline produced a significant hypertensive response (by 11.4+/-2 mm Hg) in the knockout mice only. Injection of graded doses of a selective B(1)R agonist produced a dose-dependent hypotensive response in the knockout mice only. Assessment of tissue expression of B(1)R and B(2)R genes by reverse transcription-polymerase chain reaction techniques revealed significantly higher B(1)R mRNA levels in the B(2)R knockout mice at all times (normotensive baseline and hypertensive end points). At the hypertensive end points, there was always an increase in B(1)R gene expression over the baseline values. This increase was significant in cardiac and renal tissues in all hypertensive wild-type mice but only in the clipped kidney of the renovascular knockout mice. The B(2)R gene expression in the wild-type mice remained unaffected by experimental manipulations. These results confirm the known vasodilatory and natriuretic function of the Bk B(2)R; they also indicate that in its absence, the B(1)R can become upregulated and assume some of the hemodynamic properties of the B(2)R. Furthermore, they indicate that experimental manipulations to produce hypertension also induce upregulation of the B(1)R, but not the B(2)R, in cardiac and renal tissues.
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MESH Headings
- Animals
- Blood Pressure/drug effects
- Blood Pressure/physiology
- Bradykinin/analogs & derivatives
- Bradykinin/pharmacology
- Dose-Response Relationship, Drug
- Female
- Gene Expression Regulation
- Heart/physiopathology
- Hypertension/physiopathology
- Kidney/physiopathology
- Kidney/surgery
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred Strains
- Mice, Knockout
- Myocardium/metabolism
- Nephrectomy
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptor, Bradykinin B1
- Receptor, Bradykinin B2
- Receptors, Bradykinin/drug effects
- Receptors, Bradykinin/genetics
- Receptors, Bradykinin/physiology
- Renal Artery/physiopathology
- Systole
- Time Factors
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Affiliation(s)
- I Duka
- Hypertension and Atherosclerosis Section of the Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
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43
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Gavras I, Gavras H. Benefits and side effects of blood pressure lowering treatment: what was wrong with doxazosin in the ALLHAT? Curr Control Trials Cardiovasc Med 2001; 2:257-259. [PMID: 11806808 PMCID: PMC64825 DOI: 10.1186/cvm-2-6-257] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The lowering of high blood pressure is supposed to protect target organs from hypertensive damage. The Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial was designed to compare the cardioprotective properties of three antihypertensives from different classes (lisinopril, amlodipine and doxazosin) with chlorthalidone. Despite effective blood pressure lowering and a favorable metabolic profile, the doxazosin arm of the trial had a significantly higher relative risk of cardiovascular disease and heart failure compared with the chlorthalidone arm. This article speculates on possible causes for this unexpected result and suggests that the culprit may be accentuation of the vascular effects of vasopressin, which are maximized under alpha-adrenergic blockade. These findings may have implications for the large number of older men who receive monotherapy with alpha-blockers for treatment of prostatic symptoms.
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Affiliation(s)
- Irene Gavras
- Hypertension and Atherosclerosis Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA.
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44
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DeStefano AL, Gavras H, Heard N, Bursztyn M, Manolis A, Farrer LA, Baldwin CT, Gavras I, Schwartz F. Maternal Influence on the Inheritance of Hypertension. Hypertension 2000. [DOI: 10.1161/hyp.36.suppl_1.718-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
P138
Genetic determinants of essential hypertension remain poorly understood. To date, the focus of molecular genetic research has been primarily on the nuclear genes, whereas the role of the mitochondrial genome has not been ascertained. Although mitochondrial genome is just 16.5 kilobase pairs in length and comprises less than 1% of the total nucleic acid content in mammalian cells, mitochondria occupy pivotal position in human cellular bioenergetics, and mitochondrial defects have been implicated in a wide spectrum of human genetic disorders. In contrast to nuclear inheritance, mitochondrial genome is inherited exclusively through the mother. To assess the relative maternal and paternal contributions to the familial aggregation of hypertension, we examined family history data obtained from 310 hypertensive probands (65 African American, 149 US Caucasian, 96 Greek Caucasian) ascertained without respect to parental hypertension status. Proportions of affected mothers and fathers were compared using a χ
2
test. Cumulative lifetime risk for hypertension in mothers and fathers was estimated using a maximum likelihood extension of Kaplan Meier survival analysis. We found that the proportion of hypertensive mothers was significantly greater than the proportion of hypertensive fathers in all three ethnic groups. The proportions of hypertensive mothers were 83.9, 63.2 and 83.3% for African Americans, US Caucasians and Greek Caucasians, respectively. In contrast, the observed proportions for fathers were, respectively, 53.2, 47.3 and 48.8%. In conclusion, we observe a consistent maternal component in the inheritance of hypertension in three ethnic groups. Although environmental and epigenetic influences can not be excluded, our findings provide a new dimension in the search for the genetic components of hypertension and suggest that hypertension may prove to be not only polygenic but also “polygenomic” disorder. Furthermore, our data indicate that when assessing a patient’s risk for hypertension, particular attention should be paid to the maternal portion of the family history.
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45
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Duka I, Johns C, Gavras I, Bresnahan MR, Gavras H. Role of the Bradykinin B
2
Receptor in Salt-Induced Hypertension. Hypertension 2000. [DOI: 10.1161/hyp.36.suppl_1.727-c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
P189
The kallikrein-kinin system may contribute to blood pressure (BP) regulation via its vasodilatory, natriuretic and diuretic activity. In order to explore the role of bradykinin in this respect, we studied knockout mice (n=16) with deleted gene for the B
2
receptor of bradykinin (BKB
2
R -/-), submitted to subtotal nephrectomy (SN) and dietary salt-loading, in comparison to their wildtype counterparts (BKB
2
R +/+, n=10). Systolic BP mmHg (by tail cuff), heart rate (HR b/min), plasma catecholamines, (NEPI, EPI ng/ml) and heart weight/body weight ratio (mg/g) are shown in the Table below. *p<0.05 knockouts vs wildtype. Thus, the BKB
2
R
gene knockout mice had higher BP at baseline and developed more severe hypertension. Moreover, they became hypertensive in 19±2 days versus 28±2 days for the wildtype (p<0.05). We conclude that bradykinin, acting via its B
2
receptor, contributes to maintenance of normotension and protects against salt-induced hypertension.
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46
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Abstract
A large body of literature accumulated over the past several years supports the notion that inhibition of the renin-angiotensin system protects the heart and other target organs from hypertensive complications. Various studies have shown that angiotensin-converting enzyme inhibitors reduce morbidity and mortality in the setting of ischemic heart disease and/or congestive heart failure. The improvement in survival has been attributed in part to a significant decrease in the incidence of sudden deaths, possibly due to a decrease in complex arrhythmia episodes. Recently, the angiotensin II type 1 receptor antagonist losartan was shown to reduce mortality by 46% compared with captopril in older patients with chronic congestive heart failure. This paper briefly reviews the arrhythmogenic properties of angiotensin II and the possible pharmacologic mechanisms for the antiarrhythmogenic potential of losartan.
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Affiliation(s)
- I Gavras
- Department of Medicine, Boston University School of Medicine, Massachusetts 02118, USA
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47
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Duka I, Gavras I, Johns C, Handy DE, Gavras H. Role of the postsynaptic alpha(2)-adrenergic receptor subtypes in catecholamine-induced vasoconstriction. Gen Pharmacol 2000; 34:101-6. [PMID: 10974417 DOI: 10.1016/s0306-3623(00)00051-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Catecholamines induce direct vasoconstriction mediated by postsynaptic alpha-adrenergic receptors (alpha-ARs) of both the alpha(1) and alpha(2) type. To evaluate the contribution of each alpha(2)-AR subtype (alpha(2A), alpha(2B), and alpha(2C)) to this function, we used groups of genetically engineered mice deficient for the gene to each one of these subtypes and compared their blood pressure (BP) responses to their wild-type counterparts. Blood pressure responses to a bolus of norepinephrine (NE) were assessed before and after sequential blockade of alpha(1)-ARs with prazosin and alpha(2)-ARs with yohimbine. The first NE bolus elicited a brief 32 to 44 mm Hg BP rise (p < 0.001 from baseline) in all six groups. Prazosin decreased BP by 23 to 33 mm Hg in all groups, establishing a new lower baseline. Repeat NE at that point elicited lesser but still significant (p < 0.001) brief pressor responses between 32% and 45% of the previous BP rise in five of the six groups. Only the alpha(2A)-AR gene knockouts differed, responding instead with a 20-mm Hg fall in BP, a significant change from baseline (p < 0.001) and different from the pressor response of their wild-type counterparts (p < 0.001). The addition of yohimbine produced no further BP change in the five groups, but it did produce a small 7. 5-mm Hg fall (p < 0.05) in the alpha(2A)-AR knockouts. Norepinephrine bolus during concurrent alpha(1) and alpha(2)-AR blockade produced significant (p < 0.001) hypotensive responses in all subgroups, presumably attributable to unopposed stimulation of beta(2)-vascular wall ARs. We conclude that the alpha(2)-AR-mediated vasoconstriction induced by catecholamines is attributable to the alpha(2A)-AR subtype because mice deficient in any one of the other subtypes retained the capacity for normal vasoconstrictive responses. However, the alpha(1)-ARs account for the major part (as much as 68%) of catecholamine-induced vasoconstriction.
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Affiliation(s)
- I Duka
- Hypertension and Atherosclerosis Section, Department of Medicine, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
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48
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Nicolaou M, DeStefano AL, Gavras I, Cupples LA, Manolis AJ, Baldwin CT, Gavras H, Farrer LA. Genetic predisposition to stroke in relatives of hypertensives. Stroke 2000; 31:487-92. [PMID: 10657427 DOI: 10.1161/01.str.31.2.487] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE The genetic basis of stroke is poorly understood. We evaluated patterns of familial aggregation of hypertension and stroke to test the hypothesis that inherited susceptibility to these disorders may be determined by a common set of factors. METHODS Genealogical and medical history information was obtained for a cohort of 354 hypertensive probands ascertained in a clinic-based setting, their 1427 first-degree relatives, and 239 of their spouses. Risks of stroke and hypertension in biological and nonbiological relatives were compared with the logistic model of the generalized estimating equations adjusted for age and sex. RESULTS The risk of hypertension was higher for the parents and siblings of the probands than for spouses (odds ratio [OR]=2.4; 95% CI, 1.8 to 3.4; OR=2.2; 95% CI, 1.6 to 3.0, respectively). When the spouses were used as a reference group, the risk of stroke for parents of the hypertensive probands was 7.3 times higher (OR=7.3; 95% CI, 3.6 to 14.8), while a nonsignificant but slightly increased risk for siblings (OR=1.6; 95% CI, 0.8 to 3.3) was observed. Controlling for hypertension, obesity, smoking, coronary heart disease, diabetes, and cholesterol resulted in decreased estimates of the risk of stroke for parents and siblings (OR(parents)=5.4; 95% CI, 2.6 to 11.2; OR(siblings)=1.2; 95% CI, 0.6 to 2.5). The risk of stroke was significantly higher for hypertensive parents and siblings than for nonhypertensive parents (OR=5.2; 95% CI, 2.8 to 9. 7) and siblings (OR=5.8; 95% CI, 2.1 to 15.9). A history of hypertension was not associated with an increased risk for stroke in spouses (OR=0.7; 95% CI, 0.2 to 3.1). The risk of stroke in hypertensive relatives of probands with stroke was higher than that of the normotensive relatives (OR=13.4). A less elevated risk ratio was observed in the relatives of probands who did not have a stroke (OR=4.0). CONCLUSIONS Our data showing a higher occurrence of hypertension and stroke in parents of hypertensive probands compared with spouses suggest that some of the genetic factors predisposing to these conditions may be the same. The slightly increased risk to siblings compared with spouses was not significant, suggesting that elucidation of these factors through family studies of stroke may be difficult because of secular trends toward improved treatment for hypertension. Although a history of hypertension increases the risk of stroke among parents and siblings, multivariate analyses revealed a familial component to stroke independent of hypertension.
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Affiliation(s)
- M Nicolaou
- Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
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49
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Makaritsis KP, Johns C, Gavras I, Gavras H. Role of alpha(2)-adrenergic receptor subtypes in the acute hypertensive response to hypertonic saline infusion in anephric mice. Hypertension 2000; 35:609-13. [PMID: 10679505 DOI: 10.1161/01.hyp.35.2.609] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Experimental evidence suggests that the acute hypertensive response induced in anephric animals by infusion of a hypertonic saline solution is mediated by disinhibition of the presynaptic sympathoinhibitory alpha(2)-adrenergic receptors (alpha(2)-AR) of the central nervous system. The purpose of the present experiments was to dissect the role of the 3 distinct alpha(2)-AR subtypes (alpha(2A)-, alpha(2B), - and alpha(2C)-AR) in this response. Groups of genetically engineered mice deficient in each one of these alpha(2)-AR subtype genes were submitted to bilateral nephrectomy followed by a 0.4-mL infusion of 4% saline over a 2-hour period, with constant direct blood pressure (BP) monitoring. The alpha(2A)-AR-deficient and alpha(2C)-AR-deficient mice responded with significant BP elevations (by 11.8+/-2.5 and 16.7+/-1.7 mm Hg, respectively), and so did their wild-type counterparts (17.8+/-2.5 and 11.8+/-2.0 mm Hg, respectively) and the wild-type alpha(2B) +/+ (13.1+/-2.4 mm Hg). However, the alpha(2B)-AR-deficient mice were unable to raise their BP and had a slightly lowered BP (by -3.0+/-4. 0 mm Hg) at the end of the infusion period. All 6 groups exhibited elevated plasma norepinephrine levels ranging between 0.8 and 1.8 ng/mL at the end of the infusion. In all cases, the alpha(2)-AR-deficient groups tended to have higher norepinephrine levels than their wild-type counterparts. Surprisingly, this difference was significant only in the alpha(2B)-AR-deficient mice, which, despite the elevated norepinephrine, were unable to raise their BP. The data suggest that a full complement of the alpha(2B)-AR is needed to mediate the hypertensive response to acute saline load, even though its absence does not prevent the release of norepinephrine under these conditions.
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Affiliation(s)
- K P Makaritsis
- Hypertension and Atherosclerosis Section of the Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
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50
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Gavras I, Manolis AJ, Gavras H. The economics of therapeutic advances: the paradigm of sympathetic suppression in chronic heart failure. Arch Intern Med 1999; 159:2634-6. [PMID: 10597753 DOI: 10.1001/archinte.159.22.2634] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- I Gavras
- Department of Medicine, Boston University School of Medicine, MA 02118, USA
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