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Rivarola V, Di Giusto G, Christensen MJ, Ford P, Capurro C. AQP2-Induced Acceleration of Renal Cell Proliferation Involves the Activation of a Regulatory Volume Increase Mechanism Dependent on NHE2. J Cell Biochem 2017; 118:967-978. [DOI: 10.1002/jcb.25602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 05/17/2016] [Indexed: 02/04/2023]
Affiliation(s)
- Valeria Rivarola
- Facultad de Medicina, Departamento de Ciencia Fisiológicas; Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Universidad de Buenos Aires; Buenos Aires Argentina
| | - Gisela Di Giusto
- Facultad de Medicina, Departamento de Ciencia Fisiológicas; Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Universidad de Buenos Aires; Buenos Aires Argentina
| | - María José Christensen
- Facultad de Medicina, Departamento de Ciencia Fisiológicas; Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Universidad de Buenos Aires; Buenos Aires Argentina
| | - Paula Ford
- Facultad de Medicina, Departamento de Ciencia Fisiológicas; Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Universidad de Buenos Aires; Buenos Aires Argentina
| | - Claudia Capurro
- Facultad de Medicina, Departamento de Ciencia Fisiológicas; Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Universidad de Buenos Aires; Buenos Aires Argentina
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2
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Kim KS, Abraham D, Williams B, Violin JD, Mao L, Rockman HA. β-Arrestin-biased AT1R stimulation promotes cell survival during acute cardiac injury. Am J Physiol Heart Circ Physiol 2012; 303:H1001-10. [PMID: 22886417 DOI: 10.1152/ajpheart.00475.2012] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Pharmacological blockade of the ANG II type 1 receptor (AT1R) is a common therapy for treatment of congestive heart failure and hypertension. Increasing evidence suggests that selective engagement of β-arrestin-mediated AT1R signaling, referred to as biased signaling, promotes cardioprotective signaling. Here, we tested the hypothesis that a β-arrestin-biased AT1R ligand TRV120023 would confer cardioprotection in response to acute cardiac injury compared with the traditional AT1R blocker (ARB), losartan. TRV120023 promotes cardiac contractility, assessed by pressure-volume loop analyses, while blocking the effects of endogenous ANG II. Compared with losartan, TRV120023 significantly activates MAPK and Akt signaling pathways. These hemodynamic and biochemical effects were lost in β-arrestin-2 knockout (KO) mice. In response to cardiac injury induced by ischemia reperfusion injury or mechanical stretch, pretreatment with TRV120023 significantly diminishes cell death compared with losartan, which did not appear to be cardioprotective. This cytoprotective effect was lost in β-arrestin-2 KO mice. The β-arrestin-biased AT1R ligand, TRV120023, has cardioprotective and functional properties in vivo, which are distinct from losartan. Our data suggest that this novel class of drugs may provide an advantage over conventional ARBs by supporting cardiac function and reducing cellular injury during acute cardiac injury.
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Affiliation(s)
- Ki-Seok Kim
- Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA
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3
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Muthusamy S, Shukla S, Amin MR, Cheng M, Orenuga T, Dudeja PK, Malakooti J. PKCδ-dependent activation of ERK1/2 leads to upregulation of the human NHE2 transcriptional activity in intestinal epithelial cell line C2BBe1. Am J Physiol Gastrointest Liver Physiol 2012; 302:G317-25. [PMID: 22052014 PMCID: PMC3287399 DOI: 10.1152/ajpgi.00363.2011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The apical Na+/H+ exchanger (NHE) isoform NHE2 is involved in transepithelial Na+ absorption in the intestine. Our earlier studies have shown that mitogenic agent phorbol 12-myristate 13-acetate (PMA) induces the expression of NHE2 through activation of transcription factor early growth response-1 (Egr-1) and its interactions with the NHE2 promoter. However, the signaling pathways involved in transcriptional stimulation of NHE2 in response to PMA in the intestinal epithelial cells are not known. Chemical inhibitors and genetic approaches were used to investigate the signaling pathways responsible for the stimulation of NHE2 expression by PMA via Egr-1 induction. We show that, in response to PMA, PKCδ, a member of novel PKC isozymes, and MEK-ERK1/2 pathway of mitogen-activated protein kinases stimulate the NHE2 expression in C2BBe1 intestinal epithelial cells. PMA rapidly and transiently induced activation of PKCδ. Small inhibitory RNA-mediated knockdown of PKCδ blocked the stimulatory effect of PMA on the NHE2 promoter activity. In addition, blockade of PKCδ by rottlerin, a PKCδ-specific inhibitor, and ERK1/2 by U0126, a MEK-ERK inhibitor, abrogated PMA-induced Egr-1 expression. Immunofluorescence studies revealed that inhibition of ERK1/2 activation prevents translocation of PMA-induced Egr-1 into the nucleus. Consistent with these data, PMA-induced Egr-1 interaction with the NHE2 promoter region was prevented in nuclear extracts from U0126-pretreated cells. In conclusion, our data provide the first evidence that the stimulatory effect of PMA on NHE2 expression is mediated through the initial activation of PKCδ, subsequent PKCδ-dependent activation of MEK-ERK1/2 signaling pathway, and stimulation of Egr-1 expression. Furthermore, we show that transcription factor Egr-1 acts as an intermediate effector molecule that links the upstream signaling cues to the long-term stimulation of NHE2 expression by PMA in C2BBe1 cells.
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Affiliation(s)
- Saminathan Muthusamy
- Section of Digestive Diseases and Nutrition, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Sagar Shukla
- Section of Digestive Diseases and Nutrition, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Md. Ruhul Amin
- Section of Digestive Diseases and Nutrition, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Ming Cheng
- Section of Digestive Diseases and Nutrition, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Temitope Orenuga
- Section of Digestive Diseases and Nutrition, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Pradeep K. Dudeja
- Section of Digestive Diseases and Nutrition, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Jaleh Malakooti
- Section of Digestive Diseases and Nutrition, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
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4
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Carll AP, Haykal-Coates N, Winsett DW, Hazari MS, Nyska A, Richards JH, Willis MS, Costa DL, Farraj AK. Dietary salt exacerbates isoproterenol-induced cardiomyopathy in rats. Toxicol Pathol 2011; 39:925-37. [PMID: 21878552 DOI: 10.1177/0192623311416373] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Spontaneously hypertensive heart failure rats (SHHFs) take longer to develop compensated heart failure (HF) and congestive decompensation than common surgical models of HF. Isoproterenol (ISO) infusion can accelerate cardiomyopathy in young SHHFs, while dietary salt loading in hypertensive rats induces cardiac fibrosis, hypertrophy, and--in a minority-congestive HF. By combining ISO with dietary salt loading in young SHHFs, the authors sought a nonsurgical model that is more time--and resource-efficient than any of these factors alone. The authors hypothesized that salt loading would enhance ISO-accelerated cardiomyopathy, promoting fibrosis, hypertrophy, and biochemical characteristics of HF. SHHFs (lean male, 90d) were infused for 4 wk with ISO (2.5 mg/kg/day) or saline. After 2 wk of infusion, a 6-wk high-salt diet (4%, 6%, or 8% NaCl) was initiated. Eight percent salt increased heart weight, HF markers (plasma B-type natriuretic peptide, IL-6), lung lymphocytes, and indicators of lung injury and edema (albumin and protein) relative to control diet, while increasing urine pro-atrial natriuretic peptide relative to ISO-only. High salt also exacerbated ISO-cardiomyopathy and fibrosis. Thus, combining ISO infusion with dietary salt loading in SHHFs holds promise for a new rat HF model that may help researchers to elucidate HF mechanisms and unearth effective treatments.
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Affiliation(s)
- Alex P Carll
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, North Carolina, USA
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5
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Gao C, Ye W, Li L. Three-dimension structure of ventricular myocardial fibers after myocardial infarction. J Cardiothorac Surg 2010; 5:116. [PMID: 21092295 PMCID: PMC2999601 DOI: 10.1186/1749-8090-5-116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Accepted: 11/23/2010] [Indexed: 11/10/2022] Open
Abstract
Background To explore the pathological changes of three-dimension structure of ventricular myocardial fibers after anterior myocardial infarction in dog heart. Methods Fourteen acute anterior myocardial infarction models were made from healthy dogs (mean weight 17.6 ± 2.5 kg). Six out of 14 dogs with old myocardial infarction were sacrificed, and their hearts were harvested after they survived the acute anterior myocardial infarction for 3 months. Each heart was dissected into ventricular myocardial band (VMB), morphological characters in infarction region were observed, and infarct size percents in descending segment and ascending segment were calculated. Results Six dog hearts were successfully dissected into VMB. Uncorresponding damages in myocardial fibers of descending segment and ascending segment were found in apical circle in anterior wall infarction. Infarct size percent in the ascending segment was significantly larger than that in the descending segment (23.36 ± 3.15 (SD) vs 30.69 ± 2.40%, P = 0.0033); the long axis of infarction area was perpendicular to the orientation of myocardial fibers in ascending segment; however, the long axis of the infarction area was parallel with the orientation of myocardial fibers in descending segment. Conclusions We found that damages were different in both morphology and size in ascending segment and descending segment in heart with myocardial infarction. This may provide an important insight for us to understand the mechanism of heart failure following coronary artery diseases.
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Affiliation(s)
- Changqing Gao
- Department of Cardiovascular Surgery, PLA General Hospital, 28 Fuxing Road, Beijing 100853, PR China.
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6
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Roy PP, Roy K. Exploring QSAR for CYP11B2 binding affinity and CYP11B2/CYP11B1 selectivity of diverse functional compounds using GFA and G/PLS techniques. J Enzyme Inhib Med Chem 2009; 25:354-69. [DOI: 10.3109/14756360903179476] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Partha P. Roy
- Pharmaceutical Technology, Jadavpur University, Kolkata, India
| | - Kunal Roy
- Pharmaceutical Technology, Jadavpur University, Kolkata, India
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7
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Heme Arginate Suppresses Cardiac Lesions and Hypertrophy in Deoxycorticosterone Acetate-Salt Hypertension. Exp Biol Med (Maywood) 2009; 234:764-78. [DOI: 10.3181/0810-rm-302] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In hypertension, elevated levels of oxidative/inflammatory mediators including nuclear factor kappaB (NF-κB), activating protein (AP-1), c-Jun-NH2-terminal kinase (JNK), and cell-regulatory proteins such as transforming growth factor beta (TGF-β), trigger the mobilization of extracellular matrix (ECM) leading to fibrosis, hypertrophy and impairment of cardiac function. Although the heme oxygenase (HO) system is cytoprotective, its effects on cardiac fibrosis and hypertrophy in deoxycorticosterone acetate (DOCA-salt) hypertension are not completely elucidated. Here, we report cardioprotection by the HO inducer, heme arginate against histopathological lesions in DOCA-hypertension. Treatment with heme arginate restored physiological blood pressure, and abated cardiac hypertrophy (3.75 ± 0.12 vs. 3.19 ± 0.09 g/kg body wt; n =16, P < 0.01), left-to-right ventricular ratio (6.67 ± 0.62 vs. 4.39 ± 0.63; n = 16, P < 0.01), left ventricular mass (2.48 ± 0.14 vs. 2.01 ± 0.09 g/kg body wt; n = 16, P < 0.01) and left-ventricular wall thickness (2.82 ± 0.16 vs. 1.98 ± 0.14 mm; n = 16, P < 0.01), whereas the HO inhibitor, chromium mesoporphyrin, exacerbated hypertrophy and cardiac lesions. The suppression of cardiac hypertrophy was accompanied by a robust increase in HO-1, HO activity, cyclic guanosine monophosphate (cGMP), ferritin and the total antioxidant capacity, whereas 8-isoprostane, NF-κB, JNK, AP-1, TGF-β, fibronectin and collagen-I were significantly abated. Correspondingly, histopathological parameters that depict progressive cardiac damage, including fibrosis, interstitial/perivascular collagen deposition, scarring, muscle-fiber thickness, muscular hypertrophy and coronary-arteriolar thickening were abated. Our study suggests that upregulating the HO system lowers blood pressure, potentiates the antioxidant status in tissues, suppresses oxidative stress/mediators such as NF-κB, AP-1 and cJNK, and suppresses the mobilization of ECM proteins like TGF-β, collagen and fibronectin, with corresponding reduction of cardiac histopathological lesion and hypertrophy.
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8
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Gens JS, Dou H, Tackett L, Kong SS, Chu S, Montrose MH. Different ionic conditions prompt NHE2 and NHE3 translocation to the plasma membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1023-35. [PMID: 17303069 PMCID: PMC1974857 DOI: 10.1016/j.bbamem.2007.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Revised: 12/31/2006] [Accepted: 01/04/2007] [Indexed: 11/29/2022]
Abstract
We tested whether NHE3 and NHE2 Na(+)/H(+) exchanger isoforms were recruited to the plasma membrane (PM) in response to changes in ion homeostasis. NHE2-CFP or NHE3-CFP fusion proteins were functional Na(+)/H(+) exchangers when transiently expressed in NHE-deficient PS120 fibroblasts. Confocal morphometry of cells whose PM was labeled with FM4-64 measured the fractional amount of fusion protein at the cell surface. In resting cells, 10-20% of CFP fluorescence was at PM and stable over time. A protocol commonly used to activate the Na(+)/H(+) exchange function (NH(4)-prepulse acid load sustained in Na(+)-free medium), increased PM percentages of PM NHE3-CFP and NHE2-CFP. Separation of cellular acidification from Na(+) removal revealed that only NHE3-CFP translocated when medium Na(+) was removed, and only NHE2-CFP translocated when the cell was acidified. NHE2/NHE3 chimeric proteins demonstrate that the Na(+)-removal response element resides predominantly in the NHE3 cytoplasmic tail and is distinct from the acidification response sequence of NHE2.
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Affiliation(s)
- J. Scott Gens
- Biocomplexity Institute, Indiana University, Bloomington, Indiana, 47405
| | - Hongwei Dou
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio 45267
| | - Lixuan Tackett
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5120
| | - Shen-Shen Kong
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5120
| | - Shaoyou Chu
- Eli Lilly and Company, Indianapolis, Indiana, 46225
| | - Marshall H. Montrose
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5120
- Corresponding Author: Marshall H. Montrose, Mail address: Department of Molecular and Cellular Physiology, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH 45267, Telephone number: (513)-558-5636, FAX number: (513)-558-5738, E-mail:
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9
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Thai H, Castellano L, Juneman E, Phan H, Do R, Gaballa MA, Goldman S. Pretreatment With Angiotensin Receptor Blockade Prevents Left Ventricular Dysfunction and Blunts Left Ventricular Remodeling Associated With Acute Myocardial Infarction. Circulation 2006; 114:1933-9. [PMID: 17060375 DOI: 10.1161/circulationaha.106.653329] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
This study was designed to determine the effects of pretreatment with an angiotensin receptor blocker on left ventricular (LV) function and remodeling during acute myocardial infarction (MI).
Methods and Results—
Sprague-Dawley rats were pretreated with candesartan (10 mg · kg
−1
· d
−1
) for 2 weeks and studied at 1, 3, and 6 minutes after MI. Compared with untreated rats, pretreatment with candesartan lowered (
P
<0.05) LV systolic pressure and the first derivative of LV pressure with respect to time but did not change LV end-diastolic pressure or improve LV regional function. With candesartan pretreatment, LV fractional shortening and ejection fraction increased (
P
<0.05) by 37% and 28%, and LV chamber dilation was attenuated (
P
<0.05). At 6 minutes after MI, LV endothelial nitric oxide synthase decreased in the infarcted and noninfarcted wall 47% (
P
=0.04) and 70% (
P
=0.002), and constitutive microtubulin increased 260% (
P
=0.0005) and 111% (
P
=0.003). Candesartan had no effect on LV tissue endothelial nitric oxide synthase levels but attenuated the increase in constitutive microtubulin by 77% (
P
=0.004) and 37% (
P
<0.05).
Conclusions—
Pretreatment with candesartan before an acute MI improves global LV function, prevents LV dilation, and blunts the increase in constitutive microtubulin, with minimal effects on LV hemodynamics, regional function, or tissue endothelial nitric oxide synthase. Thus, candesartan given before an MI attenuates LV remodeling and alters the cytoskeleton matrix of the left ventricle.
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Affiliation(s)
- Hoang Thai
- Cardiology Section, 1-111C, Southern Arizona VA Health Care System Hospital, 3601 S 6th Ave, Tucson, AZ 85723, USA.
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10
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Bureik M, Brück N, Hübel K, Bernhardt R. The human mineralocorticoid receptor only partially differentiates between different ligands after expression in fission yeast. FEMS Yeast Res 2005; 5:627-33. [PMID: 15780662 DOI: 10.1016/j.femsyr.2004.12.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2004] [Revised: 12/09/2004] [Accepted: 12/10/2004] [Indexed: 11/20/2022] Open
Abstract
Cardiac failure is a major health problem with increasing incidence due to aging of the population. Studies in both experimental animals and humans have suggested that aldosterone excess may have deleterious effects on cardiac function. In order to generate a novel screening system for the identification of aldosterone antagonists, we expressed the human mineralocorticoid receptor (MR) and the human glucocorticoid receptor (GR), respectively, in the fission yeast Schizosaccharomyces pombe. Reporter plasmids containing two hormone-responsive elements upstream of a fission yeast minimal promotor and either a lacZ gene (for quantification) or a neomycin gene (for survival screening) were constructed and cotransformed into fission yeast strains with expression plasmids for MR or GR. The functionality of the reporter systems was then tested using physiological ligands of both receptors as well as known inhibitors. Transactivating activity of MR could be stimulated by aldosterone, 11-deoxycorticosterone, 11-deoxycortisol, cortisol, cortisone, and spironolactone, but not by progesterone, while GR activity was stimulated by cortisol and cortisone, but also not by progesterone. Taken together, we have succeeded in establishing fission yeast-based screening systems that allow the identification of MR- or GR-interacting compounds. Moreover, our data show that after expression in fission yeast both receptors did not differentiate between steroids with different configurations at positions 11beta, 17 and 18. This finding suggests that only recognition of C-21 substituents may be accomplished by the receptor proteins alone, while the physiologically important selectivity towards other positions of the steroid ligand depends on other factors which are not conserved from fission yeast to man.
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Affiliation(s)
- Matthias Bureik
- Department of Biochemistry, Saarland University, Postfach 151150. D-66041 Saarbrücken, Germany.
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11
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Gill RK, Saksena S, Tyagi S, Alrefai WA, Malakooti J, Sarwar Z, Turner JR, Ramaswamy K, Dudeja PK. Serotonin inhibits Na+/H+ exchange activity via 5-HT4 receptors and activation of PKC alpha in human intestinal epithelial cells. Gastroenterology 2005; 128:962-74. [PMID: 15825078 DOI: 10.1053/j.gastro.2005.02.011] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Increased serotonin levels have been implicated in the pathophysiology of diarrhea associated with celiac and inflammatory diseases. However, the effects of serotonin on Na+ /H+ exchange (NHE) activity in the human intestine have not been investigated fully. The present studies examined the acute effects of 5-hydroxytryptamine (5-HT) on NHE activity using Caco-2 cells as an in vitro model. METHODS Caco-2 cells were treated with 5-HT (.1 micromol/L, 1 h) and NHE activity was measured as ethyl-isopropyl-amiloride (EIPA)-sensitive 22Na uptake. The effect of 5-HT receptor-specific agonists and antagonists was examined. The role of signaling intermediates in 5-HT-mediated effects on NHE activity was elucidated using pharmacologic inhibitors and immunoblotting. RESULTS NHE activity was inhibited significantly (approximately 50%-75%, P < .05) by .1 micromol/L 5-HT via inhibition of maximal velocity (Vmax) without any changes in apparent affinity (Km) for the substrate Na+ . NHE inhibition involved a decrease of both NHE2 and NHE3 activities. Studies using specific inhibitors and agonists showed that the effects of 5-HT were mediated by 5-HT4 receptors. 5-HT-mediated inhibition of NHE activity was dependent on phosphorylation of phospholipase C gamma 1 (PLC gamma 1) via activation of src-kinases. Signaling pathways downstream of PLC gamma 1 involved increase of intracellular Ca 2+ levels and subsequent activation of protein kinase C alpha (PKC alpha). The effects of 5-HT on NHE activity were not cell-line specific because T84 cells also showed NHE inhibition. CONCLUSIONS A better understanding of the regulation of Na+ absorption by 5-HT offers the potential for providing insights into molecular and cellular mechanisms involved in various diarrheal and inflammatory disorders.
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Affiliation(s)
- Ravinder K Gill
- Section of Digestive Diseases and Nutrition, University of Illinois at Chicago, Jesse Brown VA Medical Center, IL 60612, USA
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12
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Abstract
The sodium/hydrogen exchange (NHE) gene family plays an integral role in neutral sodium absorption in the mammalian intestine. The NHE gene family is comprised of nine members that are categorized by cellular localization (i.e., plasma membrane or intracellular). In the gastrointestinal (GI) tract of multiple species, there are resident plasma membrane isoforms including NHE1 (basolateral) and NHE2 (apical), recycling isoforms (NHE3), as well as intracellular isoforms (NHE6, 7, 9). NHE3 recycles between the endosomal compartment and the apical plasma membrane and functions in both locations. NHE3 regulation occurs during normal digestive processes and is often inhibited in diarrheal diseases. The C terminus of NHE3 binds multiple regulatory proteins to form large protein complexes that are involved in regulation of NHE3 trafficking to and from the plasma membrane, turnover number, and protein phosphorylation. NHE1 and NHE2 are not regulated by trafficking. NHE1 interacts with multiple regulatory proteins that affect phosphorylation; however, whether NHE1 exists in large multi-protein complexes is unknown. Although intestinal and colonic sodium absorption appear to involve at least NHE2 and NHE3, future studies are necessary to more accurately define their relative contributions to sodium absorption during human digestion and in pathophysiological conditions.
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Affiliation(s)
- Nicholas C Zachos
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2195, USA.
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13
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Chintalgattu V, Katwa LC. Role of Protein Kinase Cδ in Endothelin-Induced Type I Collagen Expression in Cardiac Myofibroblasts Isolated from the Site of Myocardial Infarction. J Pharmacol Exp Ther 2004; 311:691-9. [PMID: 15240825 DOI: 10.1124/jpet.104.070151] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The role of endothelin-1 (ET) in tissue remodeling/fibrogenesis has been demonstrated in various in vitro and in vivo models. Our previous studies have revealed ET-induced expression of type I collagen in cardiac myofibroblasts (myoFb). Here we report that protein kinase Cdelta (PKCdelta) and mitogen-activated protein kinase/extracellular signal-regulated kinase-1/2 (MAPK/ERK1/2) play a role in ET-induced type I collagen expression using specific pharmacological inhibitors. The present study also reveals the expression of various isoforms of PKC including PKCalpha, PKCbetaI, PKCbetaII, PKCgamma, PKCdelta, PKCepsilon, PKCeta, and PKCzeta in cardiac myoFb. Our results from mRNA and protein studies demonstrate that calphostin-C, a PKC inhibitor, decreased the ET-induced type I collagen expression suggesting a role for the PKC pathway. Further treatment with rottlerin, a PKCdelta isoform-specific inhibitor, demonstrated attenuation of 80 to 90% of type I collagen expression induced by ET. However, Go6976 [12-(2-cyanoethyl)-6,7,12,13-tetrahydro-13-methyl-5-oxo-5H-indolo[2,3-a]pyrrolo [3,4-c]carbazole]], an inhibitor of Ca(2+)-dependent PKC isoforms (PKCalpha and PKCbetaI), showed little to no effect on ET-stimulated type I collagen expression. Furthermore, the MAPK inhibitor PD98059 (2'-amino-3'-methoxyflavone) attenuated ET-dependent activation of p44/42 MAPK (pERK1/2) and also down-regulated type I collagen expression. Similarly, rottlerin inhibited the activation of p44/42 MAPK (pERK) implicating the involvement of PKC and MAPK/ERK1/2 in ET-induced type I collagen expression. Our protein/DNA array and reverse transcription-polymerase chain reaction results from ET-treated samples showed a significant increase in Sp1 expression. PD98059 and rottlerin decreased ET-induced Sp1 expression, suggesting a possible interaction of Sp1 with PKCdelta and MAPK in ET-induced type I collagen expression in cardiac myoFb.
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Affiliation(s)
- Vishnu Chintalgattu
- Department of Physiology, 6N-98, Brody Medical Sciences Bldg., East Carolina University Brody School of Medicine, 600 Moye Blvd., Greenville, NC 27834, USA
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14
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Thai H, Wollmuth J, Goldman S, Gaballa M. Angiotensin subtype 1 rReceptor (AT1) blockade improves vasorelaxation in heart failure by up-regulation of endothelial nitric-oxide synthase via activation of the AT2 receptor. J Pharmacol Exp Ther 2003; 307:1171-8. [PMID: 14560036 DOI: 10.1124/jpet.103.054916] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To determine whether angiotensin receptor blockade decreases vascular tone in heart failure by improving endothelial-dependent vasorelaxation and increasing nitric oxide (NO) bioavailability, we treated infarcted adult male Sprague-Dawley rats with candesartan for 7 days or 8 weeks (10 mg/kg/day in drinking water). Candesartan, at both time points, lowered left ventricular (LV) systolic pressure (P < 0.05) (122 +/- 22 versus 74 +/- 16 and 73 +/- 10 mm Hg) and LV dP/dt (5914 +/- 1294 versus 2857 +/- 1672 versus 3175 +/- 769 mm Hg/s), but lowered LV end-diastolic pressure only at 8 weeks (16.9 +/- 9.7 versus 11.2 +/- 5.7 versus 6.9 +/- 5.3 mm Hg). The vasorelaxation response to acetylcholine (ACh) in thoracic aortic segments was decreased with infarction (P < 0.05), remained unchanged with 1 week of candesartan, but increased 84 and 86% at 10-4 and 10-5 M ACh (P < 0.05) at 8 weeks. The enhanced candesartan-induced vasorelaxation at 8 weeks was abolished with NG-nitro-l-arginine methyl ester (200 microM). In bovine pulmonary endothelial cells, 20 microM candesartan increased endothelial nitric-oxide synthase (eNOS) protein levels (P < 0.05) (28.9 +/- 2.6 versus 16.1 +/- 3.7 intensity units/microg of protein); the increased eNOS was abolished by a specific angiotensin subtype 2 (AT2) receptor antagonist, PD 123319. These data suggest that AT1 receptor blockade enhances vasorelaxation in heart failure by increasing NO bioavailability, in part via an AT2 receptor-mediated up-regulation of eNOS protein.
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MESH Headings
- Angiotensin II Type 1 Receptor Blockers
- Animals
- Arteries/drug effects
- Benzimidazoles/pharmacology
- Biphenyl Compounds
- Blotting, Western
- Cattle
- Cells, Cultured
- Enzyme Inhibitors/pharmacology
- Heart Failure/enzymology
- Heart Failure/physiopathology
- Hemodynamics/drug effects
- Male
- Muscle Relaxation/drug effects
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Myocardial Infarction/drug therapy
- Myocardial Infarction/physiopathology
- NG-Nitroarginine Methyl Ester/pharmacology
- Nitric Oxide/metabolism
- Nitric Oxide Synthase/antagonists & inhibitors
- Nitric Oxide Synthase/biosynthesis
- Nitric Oxide Synthase Type III
- Rats
- Rats, Sprague-Dawley
- Receptor, Angiotensin, Type 2/agonists
- Tetrazoles/pharmacology
- Up-Regulation/drug effects
- Vascular Resistance/drug effects
- Ventricular Function, Left/drug effects
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Affiliation(s)
- Hoang Thai
- Cardiology Section, 1-111C, Southern Arizona Veterans Affairs Health Care System Hospital, 3601 S. 6th Avenue, Tucson, AZ 85723, USA.
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15
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Abstract
Major advances have been made during the last decade in our understanding of adrenal steroid hormone biosynthesis. Two key players in these pathways are the human mitochondrial cytochrome P450 enzymes CYP11B1 and CYP11B2, which catalyze the final steps in the biosynthesis of cortisol and aldosterone. Using data from mutations found in patients suffering from steroid hormone-related diseases, from mutagenesis studies and from the construction of three-dimensional models of these enzymes, structural information could be deduced that provide a clue to the stereo- and regiospecific steroid hydroxylation reactions carried out by these enzymes. In this review, we summarize the current knowledge on the physiological function and the biochemistry of these enzymes. Furthermore, the pharmacological and toxicological importance of these steroid hydroxylases, the means for the identification of their potential inhibitors and possible biotechnological applications are discussed.
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Affiliation(s)
- Matthias Bureik
- Universität des Saarlandes, FR 8.8 Biochemie, Postfach 151150, D-66041 Saarbrücken, Germany
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16
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Ammarguellat F, Larouche I, Schiffrin EL. Myocardial fibrosis in DOCA-salt hypertensive rats: effect of endothelin ET(A) receptor antagonism. Circulation 2001; 103:319-24. [PMID: 11208696 DOI: 10.1161/01.cir.103.2.319] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND To test the hypothesis that endothelin-1 contributes to cardiac fibrosis, cardiac collagen deposition was studied in deoxycorticosterone acetate-salt (DOCA-salt) hypertensive rats, in which the endothelin system is activated. The effects of the ET(A)-selective endothelin receptor antagonist A-127722 were evaluated. METHODS AND RESULTS A-127722 (30 mg/kg per day) was administered for 4 weeks. Myocardial fibrosis was evaluated after Sirius red F3BA staining. Systolic blood pressure was 103+/-1.6 mm Hg in unilaterally nephrectomized rats (Uni-Nx), 202+/-3.2 mm Hg in DOCA-salt rats (P:<0.01 versus Uni-Nx), and 182+/-3.1 mm Hg in ET(A) antagonist-treated DOCA-salt rats (P:<0.01 versus DOCA-salt or Uni-Nx). In DOCA-salt rats, interstitial and perivascular collagen density was increased in the subendocardial and midmyocardial regions of the left ventricle (3- to 4-fold, P:<0.05), whereas in subepicardial myocardium, the increase was predominantly perivascular. The ET(A) antagonist prevented cardiac fibrosis in DOCA-salt rats. Procollagen I and III mRNA, which were increased in hearts of DOCA-salt rats, were normalized by ET(A) antagonist treatment. TGF-beta(1) mRNA and TGF-beta(1) protein increased at 1 week in DOCA-salt rats and were lowered in ET(A) antagonist-treated rats. CONCLUSIONS ET(A) receptor-mediated collagen deposition in hearts of DOCA-salt rats results from increased procollagen synthesis associated with an initial increment in expression of TGF-beta(1). These results support the hypothesis of a role for endothelin-1 in cardiac collagen deposition in mineralocorticoid hypertension, which may have pathophysiological and pharmacological implications in hypertensive heart disease.
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Affiliation(s)
- F Ammarguellat
- Multidisciplinary Research Group on Hypertension, Clinical Research Institute of Montreal, Montréal, Québec, Canada
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17
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Karim-Jimenez Z, Hernando N, Biber J, Murer H. A dibasic motif involved in parathyroid hormone-induced down-regulation of the type IIa NaPi cotransporter. Proc Natl Acad Sci U S A 2000; 97:12896-901. [PMID: 11050158 PMCID: PMC18861 DOI: 10.1073/pnas.220394197] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Type II NaPi cotransporters are expressed in the apical membrane of P(i)-(re)absorbing epithelia: the type IIa in renal proximal tubule and the type IIb in small intestine. Parathyroid hormone (PTH) leads to a retrieval from the apical membrane of the type IIa NaPi cotransporter. The type IIa cotransporter is also expressed in opossum kidney (OK) cells, and its expression is under the control of PTH. In the present study, we identified the molecular "domains" involved in the PTH-induced retrieval of the type IIa NaPi cotransporter. Wild-type mouse type IIa (mIIa) and type IIb (mIIb) as well as several mIIa-mIIb chimeras and site-directed mutants were fused to the enhanced green fluorescent protein and transfected into OK cells. We found that mIIa but not mIIb was internalized and degraded after incubation with 1-34 (or 3-34) PTH. Using chimeras, we found that the N and C termini were not required in this effect, whereas a "domain" located between residues 216 and 658 seemed to be necessary. This region contains two putative intracellular loops with highly conserved sequences between mIIa and mIIb; in the last intracellular loop, two charged amino acids of type IIa (K(503)R(504)) are replaced by uncharged residues in type IIb (N(520)I(521)). We generated two mutants in which these residues were interchanged: mIIaNI and mIIbKR. Similarly to mIIa, the mIIbKR mutant was endocytosed in response to 1-34 PTH; in contrast, mIIaNI behaved as mIIb and was not internalized. In conclusion, a dibasic amino acid motif (K(503)R(504)) located in the last intracellular loop of the type IIa NaPi cotransporter is essential for its PTH-induced retrieval.
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Affiliation(s)
- Z Karim-Jimenez
- Institute of Physiology, University of Zürich, Zürich CH-8057, Switzerland
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18
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Sakata Y, Masuyama T, Yamamoto K, Nishikawa N, Yamamoto H, Kondo H, Ono K, Otsu K, Kuzuya T, Miwa T, Takeda H, Miyamoto E, Hori M. Calcineurin inhibitor attenuates left ventricular hypertrophy, leading to prevention of heart failure in hypertensive rats. Circulation 2000; 102:2269-75. [PMID: 11056104 DOI: 10.1161/01.cir.102.18.2269] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND There is controversy regarding the contribution of calcineurin activation to the development of pressure-overload left ventricular (LV) hypertrophy and heart failure. The aim of this study was to explore whether the inhibition of calcineurin may prevent the transition to heart failure in hypertensive rats and, if so, to clarify in which developmental stage of LV hypertrophy calcineurin plays a key role. METHODS AND RESULTS Dahl salt-sensitive rats placed on an 8% NaCl diet from the age of 7 weeks (hypertensive rats) were randomized to no treatment (n=6) or treatment with the calcineurin inhibitor FK506 (1 mg x kg(-1) x d(-1)) from 8 weeks (FKE, n=7) or from 17 weeks (FKL, n=7). Rats placed on a 0.3% NaCl diet were defined as control rats (n=6). The administration of FK506 from 8 weeks attenuated, although it did not block, LV hypertrophy observed in the untreated rats and prevented the transition to heart failure. The development of LV fibrosis, however, was not attenuated by the administration of FK506 from 8 weeks. The administration of FK506 from 17 weeks brought no benefit for cardiac remodeling or LV function and failed to prevent heart failure. CONCLUSIONS Calcineurin inhibition, if started from the initial stage of pressure overload, attenuated the development of LV hypertrophy without any effect on LV fibrosis and prevented the transition to heart failure. The activation of calcineurin is involved in the development of LV hypertrophy but not of LV fibrosis, and this involvement may be crucial at the initial stage.
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Affiliation(s)
- Y Sakata
- Department of Internal Medicine and Therapeutics, Osaka University Graduate School of Medicine, Yamadaoka, Suita 565-0871, Japan
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19
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Collazo R, Fan L, Hu MC, Zhao H, Wiederkehr MR, Moe OW. Acute regulation of Na+/H+ exchanger NHE3 by parathyroid hormone via NHE3 phosphorylation and dynamin-dependent endocytosis. J Biol Chem 2000; 275:31601-8. [PMID: 10866993 DOI: 10.1074/jbc.m000600200] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Parathyroid hormone (PTH) is a potent inhibitor of mammalian renal proximal tubule Na(+) transport via its action on the apical membrane Na(+)/H(+) exchanger NHE3. In the opossum kidney cell line, inhibition of NHE3 activity was detected from 5 to 45 min after PTH addition. Increase in NHE3 phosphorylation on multiple serines was evident after 5 min of PTH, but decrease in surface NHE3 antigen was not detectable until after 30 min of PTH. The decrease in surface NHE3 antigen was due to increased NHE3 endocytosis. When endocytic trafficking was arrested with a dominant negative dynamin mutant (K44A), the early inhibition (5 min) of NHE3 activity by PTH was not affected, whereas the late inhibition (30 min) and decreased surface NHE3 antigen induced by PTH were abrogated. We conclude that PTH acutely inhibits NHE3 activity in a biphasic fashion by NHE3 phosphorylation followed by dynamin-dependent endocytosis.
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Affiliation(s)
- R Collazo
- Medical Service, Department of Veterans Affairs Medical Center and Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75235, USA
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20
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Zornoff LA, Paiva SA, Matsubara BB, Matsubara LS, Spadaro J. Combination therapy with angiotensin converting enzyme inhibition and AT1 receptor inhibitor on ventricular remodeling after myocardial infarction in rats. J Cardiovasc Pharmacol Ther 2000; 5:203-9. [PMID: 11150409 DOI: 10.1054/jcpt.2000.7450] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND There are limited data regarding the effects of angiotensin II receptor blockade after myocardial infarction (MI). In addition, whether combined angiotensin converting enzyme (ACE) inhibitor and angiotensin II type I (AT(1)) receptor antagonist may be superior to either drug alone on ventricular remodeling remains unclear. The goal of this study was to determine if the cardiac effects of the combined administration of an ACE inhibitor and AT(1) receptor antagonist are greater than those produced by either of these agents administered individually after MI. METHODS AND RESULTS After MI, rats were divided into 4 groups: 1) untreated animals, 2) lisinopril treatment (20 mg/kg/day), 3) losartan treatment (20 mg/kg/day), and 4) lisinopril plus losartan treatment. After 3 months, the cardiac parameters studied were: mortality, fibrosis (hydroxyproline), hypertrophy (ventricular weight/body weight ratio [VW/BW]), left ventricular enlargement (volume at end-diastolic pressure equaled zero/body weight ratio [V0/BW]), and ventricular function (isovolumetric developed pressure, dp/dt, -dp/dt). A lowest mortality rate in the animals treated with the combination of both ACE inhibitor and AT(1) receptor antagonist was observed. Although lisinopril and losartan significantly decreased VW/BW ratio, when administered concomitantly, VW/BW ratio was lower than when either agent was administered individually. There were no differences in right ventricle hydroxyproline concentration. Only combination therapy decreased V0/BW ratio. The treatment with lisinopril plus losartan resulted in increases in the development of pressure versus untreated group; without alteration in dp/dt and -dp/dt. CONCLUSIONS The combination of the AT(1) receptor blockade and ACE inhibitor is more effective than individual treatment on ventricular remodeling and survival after MI in rats.
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Affiliation(s)
- L A Zornoff
- Departamento de Clínica Méedica, Faculdade de Medicina de Botucatu, Universidade Estadual Paulista-Brazil
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21
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Abstract
The renin angiotensin system was first described over 100 years ago and is still the focus of intense clinical and basic science investigation. The renin angiotensin system was demonstrated to play a major pathogenetic role in hypertension. The development of inhibitors of angiotensin-converting enzyme and specific receptor blockers for angiotensin-II represent a major advance in the treatment of elevated blood pressure. However, the renin angiotensin system is intimately involved in a number of conditions that increase the risk for atherosclerosis. Components of the renin angiotensin system have demonstrated to play a significant role in the initial phases of atherosclerosis. Additionally, plaque vulnerability and the potential for an acute atherosclerotic event are also modulated by the renin angiotensin system. Angiotensin-II plays a significant role in the balance between intravascular clot formation and fibrinolytic potential. Therefore, blocking the generation of angiotensin-II or inhibiting its binding to specific receptors may decrease the subsequent risk for unstable angina and acute myocardial infarction. Increased renin activity has been correlated as a statistical risk factor for coronary heart disease and converting enzyme inhibition has been demonstrated to decrease the incidence of acute ischemic events. This review will center on the role of modulation of the renin angiotensin system as a means to alter the clinical course of coronary atherosclerosis.
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Affiliation(s)
- J A Farmer
- Department of Internal Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
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22
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Chapter 12 Molecular physiology of mammalian epithelial Na+/H+ exchangers NHE2 and NHE3. CURRENT TOPICS IN MEMBRANES 2000. [DOI: 10.1016/s1063-5823(00)50014-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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