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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Large clinical trials have demonstrated that angiotensin-converting-enzyme (ACE) inhibitors are associated with beneficial outcomes in patients with arterial hypertension, heart failure, coronary artery disease, or a combination of these conditions. Other reports have suggested that ACE inhibitors prevent the development or recurrence of atrial fibrillation (AF), a common arrhythmia. In the TRACE trial, in patients with reduced left ventricular function after myocardial infarction, trandolapril reduced the frequency of AF. In the SOLVD trial, a 78% reduction in the frequency of AF after infarction was noted with enalapril compared with placebo. Studies in patients with persistent AF undergoing cardioversion suggest that ACE inhibitors improve outcomes and prevent AF recurrences. The mechanism of AF prevention by ACE inhibitors is unclear, but experimental data show prevention or attenuation of pacing-induced atrial remodeling with ACE inhibitor use. ACE inhibitors decrease angiotensin II concentration; angiotension II stimulates mitogen-activated protein kinases, which in turn activate fibrosis formation and lead to conduction heterogeneity and induction of AF. On the other hand, AF induces atrial dilatation, atrial stretch and atrial secretion of ACE. Among other properties, ACE inhibitors have a sympatholytic effect and increase baroreceptor sensitivity. This review discusses the current data on the use of ACE inhibitors for AF prevention. Although these drugs represent a promising therapeutic option for AF patients, the data so far seem only supportive rather than definitive. Prospective trials are required to validate the benefit of ACE inhibitors and to investigate which patients are most likely to benefit from this pharmacological therapy.
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PMID:Drug Insight: angiotensin-converting-enzyme inhibitors and atrial fibrillation--indications and contraindications. 1656 31

The existence of a tissue renin-angiotensin (RAS) system independent of the circulating RAS has prompted the search for cellular binding sites for angiotensinogen and for renin in order to explain their tissue uptake. Two receptors that bind with similar affinity mature renin and prorenin were identified, the mannose-6-phosphate receptor (M6P-R) and a specific receptor. The M6P-R is a clearance receptor that binds exclusively the glycosylated forms of renin and prorenin. Binding of renin and prorenin to the M6P-R is followed by internalization and degradation, and the intracellular proteolysis of prorenin in mature renin did not provoke any generation of intracellular angiotensins. In contrast to the M6P-R, (pro)renin bound to the specific receptor was not degraded. Instead, receptor-bound renin showed increased catalytic activity, and receptor-bound prorenin exhibited full catalytic activity. This 'gain of activity' was explained by a conformational change of the (pro)renin molecule upon binding. Furthermore, (pro)renin binding provoked a rapid activation of the mitogen-activated protein kinases p44/p42, indicating that the receptor has mediated specific, angiotensin II-independent effects of (pro)renin. This receptor represents an elegant concept to explain the existence of active prorenin in vivo, and it provides a pathological role for prorenin in situations with paradoxical low renin and high prorenin concentrations such as in diabetes. Experimental models of rats overexpressing the receptor either in vascular smooth muscle cells and developing high blood pressure or with ubiquitous expression associated with glomerulosclerosis and proteinuria confirm a role for the receptor in cardiovascular and renal diseases.
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PMID:Renin/prorenin receptors. 1667 20

Diseases such as hypertension, atherosclerosis and diabetes are associated with vascular functional and structural changes including endothelial dysfunction, altered contractility and vascular remodeling. Cellular events underlying these processes involve changes in vascular smooth muscle cell (VSMC) growth, apoptosis/anoikis, cell migration, inflammation, and fibrosis. Many stimuli influence cellular changes, including mechanical forces, such as shear stress, and vasoactive agents, of which angiotensin II (Ang II) appears to be amongst the most important. Ang II mediates many of its pleiotropic vascular effects through NAD(P)H oxidase-derived reactive oxygen species (ROS). Mechanical forces, comprising both unidirectional laminar and oscillatory shear, are increasingly being recognized as important inducers of vascular NO and ROS generation. In general, laminar flow is associated with upregulation of eNOS and NO production and increased expression of antioxidants glutathione peroxidase and superoxide dismutase, thereby promoting a healthy vascular wall and protecting against oxidative vascular injury. On the other hand, oscillatory shear is linked to increased ROS production with consequent oxidative damage, as occurs in hypertension. ROS function as important intracellular and intercellular second messengers to modulate many downstream signaling molecules, such as protein tyrosine phosphatases, protein tyrosine kinases, transcription factors, mitogen-activated protein kinases, and ion channels. Induction of these signaling cascades leads to VSMC growth and migration, expression of pro-inflammatory mediators, and modification of extracellular matrix. In addition, ROS increase intracellular free Ca(2+) concentration, a major determinant of vascular reactivity. ROS influence signaling molecules by altering the intracellular redox state and by oxidative modification of proteins. In physiological conditions, low concentrations of intracellular ROS play an important role in normal redox signaling involved in maintaining vascular function and integrity. Under pathological conditions ROS contribute to vascular dysfunction and remodeling through oxidative damage. The present review describes some of the redox-sensitive signaling pathways that are involved in the functional and structural vascular changes associated with hypertension.
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PMID:Redox signaling in hypertension. 1676 37

Cells in various anatomical locations are constantly exposed to mechanical forces from shear, tensile and compressional forces. These forces are significantly exaggerated in a number of pathological conditions arising from various etiologies e.g., hypertension, obstruction and hemodynamic overload. Increasingly persuasive evidence suggests that altered mechanical signals induce local production of soluble factors that interfere with the physiologic properties of tissues and compromise normal functioning of organ systems. Two immediate early gene-encoded members of the family of the Cyr61/CTGF/Nov proteins referred to as cysteine-rich protein 61 (Cyr61/CCN1) and connective tissue growth factor (CTGF/CCN2), are highly expressed in several mechanical stress-related pathologies, which result from either increased externally applied or internally generated forces by the actin cytoskeleton. Both Cyr61 and CTGF are structurally related but functionally distinct multimodular proteins that are expressed in many organs and tissues only during specific developmental or pathological events. In vitro assessment of their biological activities revealed that Cyr61 expression induces a genetic reprogramming of angiogenic, adhesive and structural proteins while CTGF promotes distinctively extracellular matrix accumulation (i.e., type I collagen) which is the principal hallmark of fibrotic diseases. At the molecular level, expression of the Cyr61 and CTGF genes is regulated by alteration of cytoskeletal actin dynamics orchestrated by various components of the signaling machinery, i.e., small Rho GTPases, mitogen-activated protein kinases, and actin binding proteins. This review discusses the mechanical regulation of the Cyr61 and CTGF in various tissues and cell culture models with a special attention to the cytoskeletally based mechanisms involved in such regulation.
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PMID:Mechanical regulation of the Cyr61/CCN1 and CTGF/CCN2 proteins. 1685 34

Adrenomedullin (AM) is a multifunctional peptide hormone, which plays a significant role in vasodilation and angiogenesis, implicating it in hypertension as well as in carcinogenesis. AM exerts its effects via the calcitonin receptor-like receptor (CRLR, now known as CL) complexed with either receptor activity modifying protein (RAMP) 2 or 3. We have investigated the effect of AM on immortalized human microvascular endothelial cells 1, since endothelial cells are a major source as well as a target of AM actions in vivo. Cells treated with AM showed elevated cAMP in a time (5-45 min)-dependent and dose (10(-6)-10(-14) M)-dependent manner. Pre-treatment with the AM receptor antagonist AM(22-52) partially suppressed the AM-induced increase in cAMP levels. An increase in extracellular signal-regulated kinase 1/2 phosphorylation was observed after 5 min of treatment with 10(-8) M AM. This phosphorylation was specific, since we were able to block the AM-induced effect with 1 microM U0126, a specific mitogen-activated protein/extracellular signal-regulated kinase kinase inhibitor. Using real-time PCR, we were able to show for the first time that AM upregulates peptide and mRNA expression of vascular endothelial growth factor (VEGF). However, AM treatment of cells did not result in increased cell proliferation. Instead, we observed that AM and VEGF induced cell migration, which could be inhibited by the AM(22-52) and anti-VEGF antibody respectively. AM also significantly elevated mRNA levels of CL (after 2 and 24 h treatment) and RAMP2 (after 1 and 24 h treatment). The upregulation of the AM receptor at two time points reflects possibly different cellular responses to short- and long-term exposure to AM.
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PMID:Adrenomedullin increases the expression of calcitonin-like receptor and receptor activity modifying protein 2 mRNA in human microvascular endothelial cells. 1689 83

The authors have previously shown that arterial wall strain mediates the development of vessel wall inflammation in experimental hypertension. The current studies explore the mechanoregulation of monocyte chemoattractant protein-1 (MCP-1), a potent pro-inflammatory chemokine, by mitogen-activated protein kinases (MAPK) and oxidative stress. Rat aortic smooth muscle (RASM) cells were subjected to cyclic strain on a uniform biaxial strain device. Strain rapidly activated both ERK1/2(MAPK) and p38(MAPK), with peak activation at 5 min. Strain induced a twofold increase in MCP-1 mRNA, which was attenuated by PD 98059, a specific ERK1/2(MAPK) inhibitor, and SB 203580, a specific p38(MAPK) inhibitor. Cyclic strain also increased production of superoxide anion via an NADPH oxidase-dependent mechanism. To assess the potential role of reactive oxygen species in MAPK activation, cells were stretched in the presence of N-acetylcysteine, which had no effect on p38(MAPK) activation, but significantly inhibited ERK1/2(MAPK) activation and MCP-1 expression. In conclusion, redox-sensitive activation of ERK1/2(MAPK) and redox-insensitive activation of p38(MAPK) regulate straininduced MCP-1 expression in RASM cells. These findings define a role for MAPK signal transduction in establishing a pro-inflammatory state in the arterial wall, and thus implicate a potential molecular link between arterial wall strain and atherosclerosis.
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PMID:Mechanoregulation of monocyte chemoattractant protein-1 expression in rat vascular smooth muscle cells. 1698 3

Reduced activity and expression of endothelial NO synthase (eNOS) is observed in cardiomyocytes from pressure-overloaded hearts with heart failure. The present study was aimed to investigate whether reduced eNOS-derived NO production contributes to the hypertrophic growth and phenotype of these cardiomyocytes. Cultured ventricular cardiomyocytes from adult rats were exposed to Nomega-nitro-l-arginine (l-NNA) to inhibit global NO formation, and cultured cardiomyocytes derived from eNOS-deficient mice were used as a model of genetic knockout of eNOS. Cell growth, formation of oxygen-derived radicals (reactive oxygen species [ROS]), activation of p38 mitogen-activated protein (MAP) kinase phosphorylation, and cytokine expression in cardiomyocytes were investigated. l-NNA caused a concentration-dependent acceleration of the rate of protein synthesis and an increase in cell size. This effect was sensitive to p38 MAP kinase inhibition or antioxidants. l-NNA induced a rapid increase in ROS formation, subsequent activation of p38 MAP kinase, and p38 MAP kinase-dependent increases in the expression of transforming growth factor-beta and tumor necrosis factor-alpha. Similar changes (increased ROS formation, p38 MAP kinase phosphorylation, and cytokine induction) were also observed in cardiomyocytes derived from eNOS+/+ mice when exposed to l-NNA. Cardiomyocytes from eNOS-/- mice displayed higher p38 MAP kinase phosphorylation and cytokine expression under basal conditions, but neither these 2 parameters nor ROS formation were increased in the presence of l-NNA. In conclusion, our data support the hypothesis that reduced eNOS activity in cardiomyocytes contributes to the onset of myocardial hypertrophy and increased cytokine expression, which are involved in the transition to heart failure.
Hypertension 2007 Jan
PMID:Lack of endothelial nitric oxide synthase-derived nitric oxide formation favors hypertrophy in adult ventricular cardiomyocytes. 1707 27

Cadmium (Cd) is frequently used in various industrial applications and is a ubiquitous environmental toxicant, also present in tobacco smoke. An important route of exposure is the circulatory system whereas blood vessels are considered to be main stream organs of Cd toxicity. Our previous results indicate that cadmium chloride (CdCl2) affects mean arterial blood pressure in hypertensive rats. We hypothesized that Cd alters the intracellular calcium transient mechanism, by cadmium-induced stimulation of MAPKs (ERK 1 & 2) which is mediated partially through calcium-dependent PKC mechanism. To investigate this hypothesis, we exposed primary cultures of vascular smooth muscle cells (VSMCs) from wistar kyoto (WKY) and spontaneously hypertensive rats (SHR) to increased concentrations of CdCl2 on cell viability, expression of mitogen-activated protein kinases (MAPKs/ERK 1 & 2), and protein kinase C (PKC) which are activated by Cd in several cell types. The results from these studies indicate that CdCl2 decreased cell viability of both SHR and WKY VSMCs in a concentration dependent-manner. Viability of both cell types decreased 33+/-5.3 (SHR) and 39+/-2.3% (WKY) when exposed to 1 microM CdCl2, whereas, 8 and 16 microM reduced viability by 66+/-3.1 and 62+/-4.5% in SHR cells. CdCl2 increased ERK 1 & 2 in a biphasic manner with maximum increase occurring when cells are exposed to 1 and 4 muM in SHR VSMCs, whereas, a reduction in ERK 1 and 2 is observed when WKY cells are treated with 2 microM. The results also indicate that CdCl2 increased PKC a/Beta in both SHR and WKY VSMCs with a greater increase in expression in SHR VSMCs. In addition, the [Ca2+]i chelator, BAPTA, suppressed the CdCl2 effect, whereas, the PKC inhibitor, GF109203X, reduced the CdCl2 induced-effect on PKC expression. The present studies support the hypothesis that Cd can be a risk factor of hypertension through dysfunction of vascular smooth muscle cells under certain conditions.
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PMID:Cadmium toxicity on arterioles vascular smooth muscle cells of spontaneously hypertensive rats. 1715 73

1. Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase (statins) manifest pleiotropic effects that may contribute to their therapeutic efficacy. However, the mechanism of the beneficial action of statins on cardiac hypertrophy and fibrosis remains unclear. We have now investigated this action of pitavastatin in Dahl salt-sensitive (DS) rats. 2. The DS rats progressively develop marked hypertension when fed a diet containing 8% NaCl from 7 weeks of age. These animals exhibited pronounced cardiac hypertrophy and fibrosis, as well as upregulation of fetal-type cardiac gene expression at 12 weeks of age, compared with DS rats fed a diet containing 0.3% NaCl. The abundance of mRNAs for collagen types I and III, angiotensin-converting enzyme, transforming growth factor-beta1 and connective tissue growth factor was also increased in the heart of rats on the high-salt diet. 3. Treatment of rats on the high-salt diet with a non-antihypertensive dose of pitavastatin (0.3 or 1 mg/kg per day) from 7 to 12 weeks of age attenuated the development of cardiac hypertrophy and fibrosis, as well as inhibiting the upregulation of cardiac gene expression. Pitavastatin also blocked the translocation of RhoA to the membrane fraction of the left ventricle and RhoA activation, as well as the phosphorylation of the mitogen-activated protein kinases extracellular signal-regulated kinase (ERK)-1 and ERK-2 and an increase in the DNA binding activity of serum response factor (SRF) in the heart induced by the high-salt diet. 4. These findings suggest that the effects of pitavastatin on load-induced cardiac hypertrophy and fibrosis are independent of its cholesterol-lowering action and may be mediated, at least in part, through inhibition of RhoA-ERK-SRF signalling.
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PMID:Attenuation of ventricular hypertrophy and fibrosis in rats by pitavastatin: potential role of the RhoA-extracellular signal-regulated kinase-serum response factor signalling pathway. 1718 96

The progression of renal disease displays several characteristics, including proteinuria, apoptosis, inflammation, and fibrosis. In this study, we investigated the effect of long-term infusion of kinin in protection against salt-induced renal damage in Dahl salt-sensitive rats. Dahl salt-sensitive rats were fed a high-salt diet for 2 weeks and were then infused with bradykinin (500 ng/h) via subcutaneously implanted minipumps for 3 weeks. Kinin infusion attenuated salt-induced impaired renal function as evidenced by reduced proteinuria, serum creatinine, and blood urea nitrogen levels without apparent effect on blood pressure. Morphological analysis indicated that kinin administration reduced salt-induced glomerular sclerosis, tubular dilatation, luminal protein cast formation, and interlobular arterial thickness. Kinin also significantly lowered collagen I, III, and IV deposition and their mRNA levels. Moreover, kinin reduced interstitial monocyte/macrophage accumulation, as well as tubular cell apoptosis and caspase-3 activity. Protection of renal injury by kinin was associated with increased renal NO levels and reduced nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate oxidase activities and superoxide generation. Suppression of oxidative stress by kinin was accompanied by reduced transforming growth factor-beta1 protein and mRNA levels, as well as decreased phosphorylation of mitogen-activated protein kinases. This is the first study to demonstrate that kinin infusion can directly protect against salt-induced renal injury without blood pressure reduction by inhibiting apoptosis, inflammation, and fibrosis via suppression of oxidative stress, transforming growth factor-beta1 expression, and mitogen-activated protein kinase activation.
Hypertension 2007 Mar
PMID:Kinin infusion prevents renal inflammation, apoptosis, and fibrosis via inhibition of oxidative stress and mitogen-activated protein kinase activity. 1722 75


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