Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Wild-type mice are resistant to ANG II-induced renal injury and hence form an attractive model to study renal defense against ANG II. The present study tested whether ANG II induces expression of antioxidative genes via the AT2 receptor in renal cortex and thereby counteracts prooxidative forces. ANG II was infused in female C57BL/6J mice for 28 days and a subgroup received AT2 receptor antagonist (PD-123,319) for the last 3 days. ANG II induced hypertension and aortic hypertrophy; proteinuria and renal injury were absent. Urinary nitric oxide metabolites (NOx) were decreased, and lipid peroxide (TBARS) excretion remained unchanged. Expression of NADPH oxidase components was decreased in renal cortex but induced in aorta. Heme oxygenase-1 (HO-1) was induced in both renal cortex and aorta. In contrast, ANG II suggestively increased AT2 receptor expression in kidney but not in aorta. AT2 receptor blockade enhanced hypertension in ANG II-infused mice, reversed ANG II effects on NOx excretion, but did not affect TBARS. Despite its prohypertensive effect, expression of prooxidative genes in the renal cortex decreased rather than increased after short-term AT2 receptor blockade and renal HO-1 induction after ANG II was normalized. Thus chronic ANG II infusion in mice induces hypertension but not oxidative stress. In contrast to the response in aorta, gene expression of components of NADPH-oxidase was not enhanced in renal cortex. Although ANG II administration induced renal cortical AT2 receptor expression, blockade of that receptor did not unveil the AT2 receptor as intrarenal dampening factor of prooxidative forces.
 ...
PMID:Resistance to oxidative stress by chronic infusion of angiotensin II in mouse kidney is not mediated by the AT2 receptor. 1572 90

The gp91phox-containing NADPH oxidase is the major source of reactive oxygen species (ROS) in the cardiovascular system and inactivation of gp91phox has been reported to blunt hypertension and cardiac hypertrophy seen in angiotensin (Ang) II-infused animals. In the current study, we sought to determine the role of gp91phox-derived ROS on cardiovascular outcomes of chronic exposure to Ang II. The gp91phox-deficient mice were crossed with transgenic mice expressing active human renin in the liver (TTRhRen). TTRhRen mice exhibit chronic Ang II-dependent hypertension and frank cardiac hypertrophy by age 10 to 12 weeks. Four genotypes of mice were generated: control, TTRhRen trangenics (TTRhRen), gp91phox-deficient (gp91-), and TTRhRen transgenic gp91phox-deficient (TTRhRen/gp91-). Eight to 10 mice/group were studied. ROS levels were significantly reduced (P<0.05) in the heart and aorta of TTRhRen/gp91- and gp91-mice compared with control counterparts, and this was associated with reduced cardiac, aortic, and renal NADPH oxidase activity (P<0.05). Systolic blood pressure (SBP), cardiac mass, and cardiac fibrosis were increased in TTRhRen versus controls. In contrast to its action on ROS generation, gp91phox inactivation had no effect on development of hypertension or cardiac hypertrophy in TTRhRen mice, although interstitial fibrosis was reduced. Cardiac and renal expression of gp91phox homologues, Nox1 and Nox4, was not different between groups. Thus, although eliminating gp91phox-associated ROS production may be important in cardiovascular consequences in acute insult models, it does not prevent the development of hypertension and cardiac hypertrophy in a model in which the endogenous renin-angiotensin system is chronically upregulated.
Hypertension 2005 Apr
PMID:Angiotensin II-dependent chronic hypertension and cardiac hypertrophy are unaffected by gp91phox-containing NADPH oxidase. 1575 33

Although diabetes is a major risk factor for vascular diseases, e.g., hypertension and atherosclerosis, mechanisms that underlie the "risky" aspects of diabetes remain obscure. The current study is intended to examine the notion that diabetic endothelial dysfunction stems from a heightened state of oxidative stress induced by an imbalance between vascular production and scavenging of reactive oxygen/nitrogen species. Goto-Kakizaki (GK) rats were used as a genetic animal model for non-obese type II diabetes. Nitric oxide (NO) bioavailability and O2- generation in aortic tissues of GK rats were assessed using the Griess reaction and a lucigenin-chemiluminescence-based technique, respectively. Organ chamber-based isometric tension studies revealed that aortas from GK rats had impaired relaxation responses to acetylcholine whereas a rightward shift in the dose-response curve was noticed in the endothelium-independent vasorelaxation exerted by the NO donor sodium nitroprusside. An enhancement in superoxide (O2-) production and a diminuation in NO bioavailability were evident in aortic tissues of GK diabetic rats. Immunoblotting and high-performance liquid chromatography (HPLC)-based techniques revealed, respectively, that the above inverse relationship between O2- and NO was associated with a marked increase in the protein expression of nitric oxide synthase (eNOS) and a decrease in the level of its cofactor tetrahydrobiopterin (BH4) in diabetic aortas. Endothelial denudation by rubbing or the addition of pharmacological inhibitors of eNOS (e.g. N(omega)-nitro-L-arginine methyl ester (L-NAME)), and NAD(P)H oxidase (e.g. diphenyleneiodonium, apocynin) strikingly reduced the diabetes-induced enhancement in vascular O2- production. Aortic contents of key markers of oxidative stress (isoprostane F2alpha III, protein-bound carbonyls, nitrosylated protein) in connection with the protein expression of superoxide generating enzyme NAD(P)H oxidase (e.g. p47phox, pg91phox), a major source of reactive oxygen species in vascular tissue, were elevated as a function of diabetes. In contrast, the process involves in the vascular inactivation of reactive oxygen species exemplified by the activity of CuZnSOD was reduced in this diseased state. Our studies suggest that diabetes produces a cascade of events involving production of reactive oxygen species from the NADPH oxidase leading to oxidation of BH4 and uncoupling of NOS. This promotes the oxidative inactivation of NO with subsequent formation of peroxynitrite. An alteration in the balance of these bioactive radicals in concert with a defect in the antioxidant defense counteracting mechanism may favor a heightened state of oxidative stress. This phenomenon could play a potentially important role in the pathogenesis of diabetic endothelial dysfunction.
 ...
PMID:Nitric oxide dynamics and endothelial dysfunction in type II model of genetic diabetes. 1577 79

Inflammation is associated with fibrosis. Angiotensin II-stimulated growth of fibroblasts and an increase in collagen type I synthesis are important component of the cardiac remodeling process in hypertension and chronic ischemia. AngII has been shown to enhance production of reactive oxygen species (ROS) via stimulation of nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase. Recent studies have proposed that stimulation of ROS production by AngII may constitute a means by which this humoral factor contributes to development of tissue injury in organs such as blood vessels, kidney, and the heart. Published studies have shown that PPARgamma ligands can attenuate the expression or activity of NADPH oxidase subunits. Furthermore, it has been shown that PPARs inhibits inflammation by blocking the activation of redox-sensitive transcription factor NFkappaB. Although there is much still to learn about the link of inflammation and fibrosis, PPARs are potential therapeutic targets for treating cardiac fibrosis and perivascular fibrosis.
 ...
PMID:[PPARs and fibrosis]. 1582 26

Endothelial dysfunction in the setting of cardiovascular risk factors, such as hypercholesterolemia, hypertension, diabetes mellitus, chronic smoking, as well as in the setting of heart failure, has been shown to be at least partly dependent on the production of reactive oxygen species (ROS), such as the superoxide radical, and the subsequent decrease in vascular bioavailability of nitric oxide (NO). Superoxide-producing enzymes involved in increased oxidative stress within vascular tissue include the NAD(P)H oxidase, the xanthine oxidase, and mitochondrial superoxide-producing enzymes. Superoxide produced by the NADPH oxidase may react with NO released by endothelial nitric oxide synthase (eNOS), thereby generating peroxynitrite. Peroxynitrite in turn has been shown to uncouple eNOS, thereby switching an antiatherosclerotic NO-producing enzyme to an enzyme that may initiate or even accelerate the atherosclerotic process by producing superoxide. Increased oxidative stress in the vasculature, however, is not restricted to the endothelium and has also been demonstrated to occur within the smooth muscle cell layer in the setting of hypercholesterolemia, diabetes mellitus, hypertension, congestive heart failure, and nitrate tolerance. Increased superoxide production by the endothelial and/or smooth muscle cells has important consequences with respect to signaling by the soluble guanylyl cyclase (sGC) and the cGMP-dependent protein kinase I (cGK-I), the activity and expression of which has been shown to be regulated in a redox-sensitive fashion. The present review summarizes current concepts concerning eNOS uncoupling and also focuses on the consequences for downstream signaling with respect to activity and expression of the sGC and cGK-I in various diseases.
 ...
PMID:Vascular consequences of endothelial nitric oxide synthase uncoupling for the activity and expression of the soluble guanylyl cyclase and the cGMP-dependent protein kinase. 1587 5

Oxidative stress plays an important role in the pathophysiology of vascular diseases. Reactive oxygen species, especially superoxide anion and hydrogen peroxide, are important signalling molecules in cardiovascular cells. Enhanced superoxide production increases nitric oxide inactivation and leads to an accumulation of peroxynitrites and hydrogen peroxide. Reactive oxygen species participate in growth, apoptosis and migration of vascular smooth muscle cells, in the modulation of endothelial function, including endothelium-dependent relaxation and expression of proinflammatory phenotype, and in the modification of the extracellular matrix. All these events play important roles in vascular diseases such as hypertension, suggesting that the sources of reactive oxygen species and the signalling pathways that they modify may represent important therapeutic targets. Potential sources of vascular superoxide production include NADPH-dependent oxidases, xanthine oxidases, lipoxygenases, mitochondrial oxidases and nitric oxide synthases. Studies performed during the last decade have shown that NADPH oxidase is the most important source of superoxide anion in phagocytic and vascular cells. Evidence from experimental animal and human studies suggests a significant role of NADPH oxidase activation in the vascular remodelling and endothelial dysfunction found in cardiovascular diseases.
 ...
PMID:Oxidative stress and vascular remodelling. 1589 Jul 97

Insulin resistance and central obesity are often associated with hypertension. The metabolic syndrome is a cluster of these common clinical disorders, and is related with an increased risk for cardiovascular diseases. A number of pro-inflammatory cytokines derived from adipose tissues have been thought to contribute to the development of insulin resistance and accelerated atherosclerosis. Among them, TNF-alpha has been most widely studied; it not only suppresses the insulin signaling, but also elicits vascular inflammation. Indeed, inhibition of TNF-alpha was found to improve insulin resistance in obese rats and reduce the progression of atherosclerosis in apolipoprotein E knockout mice, respectively. These observations demonstrate that TNF-alpha could play a central role in the pathogenesis of insulin resistance and accelerated atherosclerosis in the metabolic syndrome. Considering that the primary goals of treatment for hypertensive patients with the metabolic syndrome are prevention of the development of diabetes and cardiovascular events, anti-hypertensive drugs that have abilities to block the TNF-alpha signaling would be desirable as a first-line therapy for these patients. In the process of the search for such a unique anti-hypertensive drug, we have recently found that azelnidipine, a newly developed and commercially used long-acting dihydropyridine-based calcium antagonist (DHP), inhibited TNF-alpha-induced activator protein-1 activation and interleukin-8 expression in human umbilical vein endothelial cells by suppressing NADPH oxidase-mediated reactive oxygen species generation. The concentration of azelnidipine that was found effective in these in vitro-experiments is well within the therapeutic range. Since endothelial cells do not possess voltage-operated L-type calcium channels, these observations suggest that the beneficial effects of azelnidipine are not likely due to calcium channel blocking property, but due to its unique anti-oxidative ability. Furthermore, we have very recently found that serum levels of monocyte chemoattractant protein-1, a biomarker for subclinical atherosclerosis, were significantly decreased by the treatment of azelnidipine in patients with essential hypertension. In this paper, we would like to hypothesize that due to its unique TNF-alpha signal modulatory, anti-oxidative property, azelnidipine may be a promising DHP that targets diabetes and cardiovascular diseases in hypertensive patients with the metabolic syndrome.
 ...
PMID:Unique atheroprotective property of azelnidipine, a dihydropyridine-based calcium antagonist. 1589 34

Renal oxygen tension is substantially lower in the medulla than in the cortex and is reduced in hypertensive rats, a model of oxidative stress. Expression of NADPH oxidase, the primary source for superoxide anion (O(2)(-)*) in the kidney, is elevated in hypertension. Because molecular oxygen (O(2)) is required for O(2)(-)* formation, we tested the hypothesis that renal NADPH oxidase activity is limited by low O(2). O(2)(-)* production by rat kidney tissue or cultured cells exposed to levels of Po(2) that mimics those in the kidney was assessed by lucigenin-enhanced chemiluminescence. NADPH-dependent O(2)(-)* production by kidney homogenates decreased reversibly by 60-90% after graded reductions of ambient O(2) from 10 to 0% (76 to 2 mmHg Po(2)). The NADPH-dependent O(2)(-)* production by the kidney homogenate was reduced by decreasing Po(2) below approximately 30 mmHg. The response of tissue homogenates to low Po(2) was not different between normotensive and hypertensive rats. Similarly, NADPH-dependent O(2)(-)* production was lower during 2% O(2) compared with 10% O(2) in rat proximal tubule cells (-57 +/- 1%), vascular smooth muscle (-42 +/- 5%), cardiomyocytes (-57 +/- 1%), and mouse inner medulla collecting duct cells (-58 +/- 3%). We conclude that O(2)(-)* production by NADPH oxidase is dependent on availability of O(2). Therefore, O(2)(-)* generation may be limited in the kidney, both in the normal renal medulla and in the cortex of hypertensive kidneys.
 ...
PMID:Oxygen availability limits renal NADPH-dependent superoxide production. 1594 50

Oxidative stress underlies many forms of vascular disease as well as tissue injury following ischemia and reperfusion. The major source of oxidative stress in the artery wall is an NADPH oxidase. This enzyme complex as expressed in vascular cells differs from that in phagocytic leucocytes both in biochemical structure and functions. The crucial flavin-containing catalytic subunits, Nox1 and Nox4, are not found in leucocytes, but are highly expressed in vascular cells and upregulated with vascular remodeling, such as that found in hypertension and atherosclerosis. The difference in catalytic subunits offers the opportunity to develop "vascular specific" NADPH oxidase inhibitors that do not compromise the essential physiological signaling and phagocytic functions carried out by reactive oxygen and nitrogen species. Nitric oxide and targeted inhibitors of NADPH oxidase that block the source of oxidative stress in the vasculature are more likely to prevent the deterioration of vascular function that leads to stroke and heart attack, than are conventional antioxidants. The roles of Nox isoforms in other inflammatory conditions are yet to be explored.
 ...
PMID:Mechanisms for suppressing NADPH oxidase in the vascular wall. 1596 5

The major risk factors for intracerebral hemorrhage (ICH) are hypertension and aging. A fundamental mechanism for hypertension- and aging-induced vascular injury is oxidative stress. We hypothesize that oxidative stress has a crucial role in ICH. To test our hypothesis, we used bacterial collagenase to produce ICH in wild-type C57BL/6 and gp91phox knockout (gp91phox KO) mice (deficient in gp91phox subunit of the superoxide-producing enzyme NADPH oxidase). All animals were studied at 20-35 weeks of age, resembling an older patient population. We found that collagenase produced less bleeding in gp91phox KO mice than wild-type mice. Total oxidative product was lower in gp91phox KO mice than in wild-type mice, both under basal conditions and after ICH. Consistent with the ICH volume, brain edema formation, neurological deficit and a high mortality rate was noted in wild-type but not in gp91phox KO mice. This ICH-induced brain injury in wild-type mice is associated with enhanced expression of the gp91phox subunit of NADPH oxidase. In conclusion, the oxidative stress resulting from activation of NADPH oxidase contributes to ICH induced by collagenase and promotes brain injury.
 ...
PMID:Role of NADPH oxidase in the brain injury of intracerebral hemorrhage. 1601 43


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>