Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P47989 (xanthine oxidase)
 8,633 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The plasma level of the uric acid is frequently elevated in heart failure, due to increased production and/or to reduced renal excretion of this antioxidant metabolite. The transformation of hypoxanthine to xanthine and the conversion of the latter into uric acid, which occur in purine catabolism, are catalysed by xanthine oxidoreductase. The constitutive xanthine dehydrogenase form of this enzyme generally uses NAD(+) as an electron acceptor, whereas the post-translational xanthine oxidase form uses molecular oxygen and yields four units of reactive oxygen species per unit of transformed substrate. Allopurinol and oxypurinol inhibit xanthine oxidoreductase and thus diminish the generation of reactive species and decrease plasma uric acid. In a recent study in patients with NHYA class II-III heart failure, add-on treatment with allopurinol 300 mg/day for 3 months lowered plasma uric acid but failed to improve laboratory exercise performance or the distance walked in 6 minutes. In another recent trial, which was carried out in patients with NHYA class III-IV heart failure, add-on treatment with oxypurinol 600 mg/day for 24 weeks decreased plasma uric acid concentration but did not change a composite of patient outcome and state. These results indicate that the reduction in plasma uric acid caused by allopurinol or oxypurinol does not benefit patients with heart failure. Moreover, the hypothesis that the diminution in the renal excretion of the antioxidant uric acid caused by diuretics may be salutary in cardiac failure is strengthened by the study results considered.
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PMID:Allopurinol or oxypurinol in heart failure therapy - a promising new development or end of story? 1638 92

The prototypical xanthine oxidase (XO) inhibitor allopurinol, has been the cornerstone of the clinical management of gout and conditions associated with hyperuricemia for several decades. More recent data indicate that XO also plays an important role in various forms of ischemic and other types of tissue and vascular injuries, inflammatory diseases, and chronic heart failure. Allopurinol and its active metabolite oxypurinol showed considerable promise in the treatment of these conditions both in experimental animals and in small-scale human clinical trials. Although some of the beneficial effects of these compounds may be unrelated to the inhibition of the XO, the encouraging findings rekindled significant interest in the development of additional, novel series of XO inhibitors for various therapeutic indications. Here we present a critical overview of the effects of XO inhibitors in various pathophysiological conditions and also review the various emerging therapeutic strategies offered by this approach.
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PMID:Therapeutic effects of xanthine oxidase inhibitors: renaissance half a century after the discovery of allopurinol. 1650 84

Myocardial oxidative stress and Ca2+ overload induced by ischemia-reperfusion may be involved in the development and progression of myocardial dysfunction in heart failure. Xanthine oxidase, which is capable of producing reactive oxygen species, is considered as a culprit regarding ischemia-reperfusion injury of cardiomyocytes. Even though inhibition of xanthine oxidase by allopurinol in failing hearts improves cardiac performance, the regulatory mechanisms are not known in detail. We therefore hypothesized that allopurinol may prevent the xanthine oxidase-induced reactive oxygen species production and Ca2+ overload, leading to decreased calcium-responsive signaling in myocardial dysfunction. Allopurinol reversed the increased xanthine oxidase activity in ischemia-reperfusion injury of neonatal rat hearts. Hypoxia-reoxygenation injury, which simulates ischemia-reperfusion injury, of neonatal rat cardiomyocytes resulted in activation of xanthine oxidase relative to that of the control, indicating that intracellular xanthine oxidase exists in neonatal rat cardiomyocytes and that hypoxia-reoxygenation induces xanthine oxidase activity. Allopurinol (10 microM) treatment suppressed xanthine oxidase activity induced by hypoxia-reoxygenation injury and the production of reactive oxygen species. Allopurinol also decreased the concentration of intracellular Ca2+ increased by enhanced xanthine oxidase activity. Enhanced xanthine oxidase activity resulted in decreased expression of protein kinase C and sarcoendoplasmic reticulum calcium ATPase and increased the phosphorylation of extracellular signal-regulated protein kinase and p38 kinase. Xanthine oxidase activity was increased in both ischemia-reperfusion-injured rat hearts and hypoxia-reoxygenation-injured cardiomyocytes, leading to reactive oxygen species production and intracellular Ca2+ overload through mechanisms involving p38 kinase and extracellular signal-regulated protein kinase (ERK) via sarcoendoplasmic reticulum calcium ATPase (SERCA) and protein kinase C (PKC). Xanthine oxidase inhibition with allopurinol modulates reactive oxygen species production and intracellular Ca2+ overload in hypoxia-reoxygenation-injured neonatal rat cardiomyocytes.
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PMID:Allopurinol modulates reactive oxygen species generation and Ca2+ overload in ischemia-reperfused heart and hypoxia-reoxygenated cardiomyocytes. 1651 85

Substantial evidence suggests the involvement of oxidative stress in the pathophysiology of congestive heart failure and its antecedent conditions such as cardiac hypertrophy and adverse remodelling after MI. Oxidative stress describes an imbalance between antioxidant defences and the production of reactive oxygen species (ROS), which at high levels cause cell damage but at lower levels induce subtle changes in intracellular signalling pathways (termed redox signalling). ROS are derived from many sources including mitochondria, xanthine oxidase, uncoupled nitric oxide synthases and NADPH oxidases. The latter enzymes are especially important in redox signalling, being implicated in the pathophysiology of hypertension and atherosclerosis, and activated by diverse pathologically relevant stimuli. We review the contribution of ROS to heart failure pathophysiology and discuss potential therapies that may specifically target detrimental redox signalling. Indeed, drugs such as ACE inhibitors and statins may act in part through such mechanisms. A better understanding of redox signalling mechanisms may enable the development of new targeted therapeutic strategies rather than the non-specific antioxidant approaches that have to date been disappointing in clinical trials.
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PMID:Oxidative stress and redox signalling in cardiac hypertrophy and heart failure. 1667 Jan

Reactive oxygen species (ROS) contribute to the pathogenesis of cardiovascular diseases including hypertension, atherosclerosis, cardiac hypertrophy, heart failure and diabetes mellitus. Oxidative stress is resulted from excessive generation of ROS that outstrips the antioxidant system. Various agonists, pathological conditions and therapeutic interventions lead to modulated expression and function of oxidant and antioxidant enzymes, including NAD(P)H oxidase, endothelial nitric oxide synthase, xanthine oxidase, myeloperoxidase, superoxide dismutases, catalase and glutathione peroxidase. ROS formed in vascular wall target a wide range of signaling molecules and cellular pathways in both endothelium and vascular smooth muscle, such as transcription factors, protein tyrosine phosphatase, protein tyrosine kinase, mitogen-activated protein kinase, Ca(2+)-transporting system and protein modification. ROS also have distinct physiological and pathophysiological impacts on vascular cells. ROS contribute to vascular dysfunction and remodeling through oxidative damage by (1) reducing the bioavailability of NO, (2) impairing endothelium-dependent vasodilatation and endothelial cell growth, (3) causing apoptosis or anoikis, (4) stimulating endothelial cell migration, and (5) activating adhesion molecules and inflammatory reaction, leading to endothelial dysfunction, an initial episode progressing toward hypertension and atherosclerosis. Cellular events underlying these processes involve changes in vascular smooth muscle cell growth, apoptosis/anoikis, cell migration, inflammation, and vasoconstriction. The present communication focuses on the biology of ROS signaling in vascular cells, discusses how oxidative stress contributes to vascular damage, and the therapeutic strategies/biotic factors that can prevent or treat ROS-associated cardiovascular disorders.
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PMID:Reactive oxygen species in vascular wall. 1672 32

Reactive oxygen species, in particular superoxide, have been closely linked to the underlying pathophysiology of ischemic cardiomyopathy: superoxide not only mediates mechanoenergetic uncoupling of the myocyte but also adversely impacts on myocardial perfusion by depleting endothelial-derived nitric oxide bioavailability. Xanthine oxidase generates superoxide upon oxidation of hypoxanthine and xanthine and has been detected in cardiac myocytes and coronary endothelial cells of patients with ischemic heart disease. Here we investigated the effects of oxypurinol, a xanthine oxidase inhibitor, on myocardial contractility in patients with ischemic cardiomyopathy. Twenty patients (19 males, 66+/-8 years) with stable coronary disease, severely suppressed systolic function (left ventricular ejection fraction 22+/-2%), and nonelevated uric acid plasma levels received a single intravenous dose of oxypurinol (400 mg). Cardiac MRI studies, performed before and 5.2+/-0.9 h after oxypurinol administration, revealed a reduction in end-systolic volumes (-9.7+/-4.2%; p=0.03) and an increase in left ventricular ejection fraction (+17.5+/-5.2%; p=0.003), whereas 6 patients (6 males, 63+/-3.8 years, ejection fraction 26+/-5%) who received vehicle only did not show significant changes in any of the parameters studied. Oxypurinol improves left ventricular function in patients with ischemic cardiomyopathy. These results underscore the significance of reactive oxygen species as important pathophysiological mediators in ischemic heart failure and point toward xanthine oxidase as an important source of reactive species that serve to modulate the myocardial redox state in this disease.
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PMID:Inhibition of xanthine oxidase improves myocardial contractility in patients with ischemic cardiomyopathy. 1701 75

Xanthine oxidase (XO) activity contributes to both abnormal excitation-contraction (EC) coupling and cardiac remodeling in heart failure (HF). beta-Adrenergic hyporesponsiveness and abnormalities in Ca(2+) cycling proteins are mechanistically linked features of the HF phenotype. Accordingly, we hypothesized that XO influences beta-adrenergic responsiveness and expression of genes whose products participate in deranged EC coupling. We measured inotropic (dP/dt(max)), lusitropic (tau), and vascular (elastance; E(a)) responses to beta-adrenergic (beta-AR) stimulation with dobutamine in conscious dogs administered allopurinol (100 mg po daily) or placebo during a 4-wk induction of pacing HF. With HF induction, the decreases in both baseline and dobutamine-stimulated inotropic responses were offset by allopurinol. Additionally, allopurinol converted a vasoconstrictor effect to dobutamine to a vasodilator response and enhanced both lusitropic and preload reducing effects. To assess molecular correlates for this phenotype, we measured myocardial sarcoplasmic reticulum Ca(2+)-ATPase 2a (SERCA), phospholamban (PLB), phosphorylated PLB (P-PLB), and Na(+)/Ca(2+) transporter (NCX) gene expression and protein. Although SERCA mRNA and protein concentrations did not change with HF, both PLB and NCX were upregulated (P < 0.05). Additionally, P-PLB and protein kinase A activity were greatly reduced. Allopurinol ameliorated all of these molecular alterations and preserved the PLB-to-SERCA ratio. Preventing maladaptive alterations of Ca(2+) cycling proteins represents a novel mechanism for XO inhibition-mediated preservation of cardiac function in HF, raising the possibility that anti-oxidant therapies for HF may ameliorate transcriptional changes associated with adverse cardiac remodeling and beta-adrenergic hyporesponsiveness.
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PMID:Chronic allopurinol administration ameliorates maladaptive alterations in Ca2+ cycling proteins and beta-adrenergic hyporesponsiveness in heart failure. 1707 24

We investigated whether xanthine oxidase inhibition with febuxostat enhances left ventricular (LV) function and improves myocardial high energy phosphates (HEP) in dogs with pacing-induced heart failure (CHF). Febuxostat (2.2 mg/kg over 10 minutes followed by 0.06 mg/kg/min) caused no change of LV function or myocardial oxygen consumption (MVO2) at rest or during treadmill exercise in normal dogs. In dogs with CHF, febuxostat increased LV dP/dtmax at rest and during heavy exercise (P < 0.05), indicating improved LV function with no change of MVO2. Myocardial adenosine triphosphate (ATP) and phosphocreatine (PCr) were examined using 31P nuclear magnetic resonance spectroscopy in the open chest state. In normal dogs, febuxostat increased PCr/ATP during basal conditions and during high workload produced by dobutamine + dopamine (P < 0.05). PCr/ATP was decreased in animals with CHF; in these animals, febuxostat (given after completing basal and high workload measurements with vehicle) tended to increase PCr/ATP during basal conditions with no effect during catecholamine stimulation. Thus, febuxostat improved LV performance in awake dogs with CHF, but caused only a trend toward increased PCr/ATP in the open chest state. It is possible that the antecedent high workload condition prior to drug administration blunted the effect of febuxostat on HEP in the CHF animals. Alternatively, beneficial effects of febuxostat on LV performance in the failing heart may not involve HEP.
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PMID:Acute effects of febuxostat, a nonpurine selective inhibitor of xanthine oxidase, in pacing induced heart failure. 1711 Aug 8

Accumulating evidence suggests a critical role of increased reactive oxygen species production for left ventricular (LV) remodeling and dysfunction after myocardial infarction (MI). An increased myocardial activity of the NAD(P)H oxidase, a major oxidant enzyme system, has been observed in human heart failure; however, the role of the NAD(P)H oxidase for LV remodeling and dysfunction after MI remains to be determined. MI was induced in wild-type (WT) mice (n=46) and mice lacking the cytosolic NAD(P)H oxidase component p47(phox) (p47(phox)-/- mice) (n=32). Infarct size was similar among the groups. NAD(P)H oxidase activity was markedly increased in remote LV myocardium of WT mice after MI as compared with sham-operated mice (83+/-8 versus 16.7+/-3.5 nmol of O(2)(-) x microg(-1) x min(-1); P<0.01) but not in p47(phox)-/- mice after MI (13.5+/-3.6 versus 15.5+/-3.5 nmol of O(2)(-) x microg(-1) x min(-1)), as assessed by electron-spin resonance spectroscopy using the spin probe CP-H. Furthermore, increased myocardial xanthine oxidase activity was observed in WT, but not in p47(phox)-/- mice after MI, suggesting NAD(P)H oxidase-dependent xanthine oxidase activation. Myocardial reactive oxygen species production was increased in WT mice, but not in p47(phox)-/- mice, after MI. LV cavity dilatation and dysfunction 4 weeks after MI were markedly attenuated in p47(phox)-/- mice as compared with WT mice, as assessed by echocardiography (LV end-diastolic diameter: 4.5+/-0.2 versus 6.3+/-0.3 mm, P<0.01; LV ejection fraction, 35.8+/-2.5 versus 22.6+/-4.4%, P<0.05). Furthermore, cardiomyocyte hypertrophy, apoptosis, and interstitial fibrosis were substantially reduced in p47(phox)-/- mice as compared with WT mice. Importantly, the survival rate was markedly higher in p47(phox)-/- mice as compared with WT mice after MI (72% versus 48%; P<0.05). These results suggest a pivotal role of NAD(P)H oxidase activation and its subunit p47(phox) for LV remodeling/dysfunction and survival after MI. The NAD(P)H oxidase system represents therefore a potential novel therapeutic target to prevent cardiac failure after MI.
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PMID:Critical role of the NAD(P)H oxidase subunit p47phox for left ventricular remodeling/dysfunction and survival after myocardial infarction. 1733 31

Adverse cardiac remodeling is a fundamental process in the progression to chronic heart failure. Although the mechanisms underlying cardiac remodeling are multi-factorial, a significant body of evidence points to the crucial roles of increased reactive oxygen species. This article reviews recent advances in delineating the different sources of production for reactive oxygen species (namely mitochondria, xanthine oxidase, uncoupled nitric oxide synthases, and NADPH oxidases) that may be involved in cardiac remodeling and the aspects of the remodeling process that they affect. These data could suggest new ways of targeting redox pathways for the prevention and treatment of adverse cardiac remodeling.
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PMID:Role of reactive oxygen species in myocardial remodeling. 1738 82


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