Role of oxidative stress in cardiovascular diseases

Effects of purified herbal extract of Salvia miltiorrhiza on ischemic rat myocardium after acute myocardial infarction

In the current study, we compared purified Salvia miltiorrhiza extract (PSME) with Angiotensin-converting enzyme inhibitor, Ramipril, in in vitro experiments and also in vivo using animal model of myocardial infarction. PSME was found to have a significantly higher trolox equivalent antioxidant capacity which indicated a great capacity for scavenging free radicals. PSME could also prevent pyrogallo red bleaching and DNA damage. After 2 weeks treatment with PSME or Ramipril, survival rates of rats with experimental myocardial infarction were marginally increased (68.2% and 71.4%) compared with saline (61.5%). The ratios of infarct size to left ventricular size in both PSME-and Ramipril-treated rats were significantly less than that in the saline-treated group. Activity of cardiac antioxidant enzyme superoxide dismutase (SOD) was significant higher while level of Thiobarbituric acid-reactive substances (TBARs) was lower in the PSME treated group. Purified and standardized Chinese herb could provide an alternative regimen for the prevention of ischemic heart disease.

Heme oxygenase-2 products activate IKCa: role of CO and iron in guinea pig portal vein smooth muscle cells

Hemin (10 microM) and carbon monoxide (CO) increased iberiotoxin-blockable IKCa in portal vein smooth muscle cells. CO-induced IKCa activation was abolished by 10 microM ODQ, 10 microM cyclopiazonic acid and 1 microM KT5823. The hemin-induced effect on IKCa was abolished by pretreatment with Sn-protoporphyrin IX, a heme oxygenase inhibitor and Fe2+ chelator but was insensitive to inhibitors of soluble guanylate cyclase (GC) and cGMP-dependent protein kinase (PKG). There was no effect of hemin on IKCa in the presence of 3 microM dithiotreitol into the bath or 3 mM glutathione into the pipette solution. Superoxide dismutase (1000 U/ml) or catalase (3000 U/ml) added into the pipette solution also abolished the effect of hemin on IKCa in this tissue. Additionally, 10 microM hemin could not influence IKCa in Ca2+-free external solution or in the presence of 30 microM SKF 95356. It was concluded that CO increases IKCa via its "conventional" signaling pathway, which involves soluble GC and PKG activation and subsequent stimulation of sarcoplasmic reticulum Ca2+ pump activity resulting in Ca2+-dependent activation of IKCa due to the accumulation of Ca2+ into the space near the plasma membrane. On the other hand, internally produced CO could not yield the same IKCa increase, while Fe2+ derived from heme oxygenase 2-dependent degradation of hemin in portal vein smooth muscle cells gives rise to reactive oxygen species namely hydroxyl and superoxide radicals. Both radicals are responsible for the SKF 95356-sensitive non-selective cation channel activation, the Ca2+ influx and the subsequent increase of Ca2+ concentration near the plasma membrane that augments the KCa channel activity.

Oxidative stress in hypertension

Several experimental and clinical evidences have linked an enhanced production of reactive oxygen species (ROS) to certain diseases of the cardiovascular system including hypertension and diabetes. However, it has never been clearly established whether the enhanced oxidative stress observed in those conditions is primary or secondary to the pathological process. Our experimental studies have permitted to demonstrate that ROS, mainly through the production of superoxide anion, can cause important alterations in the cellular signal transduction systems characterized by an enhanced production of inositol triphosphate and a reduced production of cyclic GMP in cultured vascular smooth muscle cells (SMC), thus favouring the vasoconstriction. Since those effects were found to be increased in SMC from spontaneously hypertensive rats (SHR), this suggested a greater sensitivity of the vascular tissue of SHR to the oxidative stress. Moreover, we also have observed an increased production of superoxide anion in the aorta of rats made hypertensive according to the SHR, glucose or angiotensin-induced and DOCA-salt models during the development of hypertension. Since the superoxide anion production could be correlated with the level of blood pressure and since the development of hypertension could be either totally prevented or markedly attenuated by chronic treatment with potent antioxidative therapies such as alpha lipoic acid or aspirin, this suggested a major contribution of vascular superoxide anion production in the development of hypertension in those models. Moreover, the development of insulin resistance, which is associated to the model of glucose-induced hypertension, was also found to be prevented by chronic antioxidant therapies, thus suggesting that oxidative stress plays an important role as well in the development of insulin resistance and type 2 diabetes. In conclusion, it appears that oxidative stress may constitute a major pathogenic factor in the development of hypertension and type 2 diabetes. Moreover, our studies suggest that the chronic treatment with appropriate antioxidative therapies could prevent the development of hypertension and diabetes as well as their complications in various experimental models of hypertension.

Heart failure and statins—Why do we need a clinical trial?

The effect of statins to reduce mortality and morbidity in primary and secondary prevention as well as in acute coronary syndrome is well established. Recent data show that pleiotropic effects might also have direct effects on the myocardial cell. However, in chronic heart failure the outcome is inversely related to LDL-plasma concentrations and other pleiotropic effects might impair mitochondrial function. Since there are no safety data on the use of statins in chronic heart failure, a controlled randomized and placebo-controlled trial is urgently needed.

Antioxidants and ecto-5'-nucleotidase are not involved in the training-induced cardioprotection against ischaemia-reperfusion injury

Isolated Langendorff-perfused hearts from sedentary and prolonged (24 weeks) treadmill-trained rats were subjected to 30 min of normoxic perfusion either alone or followed by 20 min of global ischaemia, or by 20 min of global ischaemia and 15 min of normoxic reperfusion. Pre-ischaemic values of antioxidant enzyme activities and ecto-5'-nucleotidase activity were not different in sedentary and trained hearts but a 5-fold increase of 72-kDa heat shock protein (HSP72) levels was detected in trained myocardium. After ischaemia and reperfusion (I/R), metabolic recovery was better in trained than in sedentary hearts as indicated by higher ATP and creatine phosphate levels. However, antioxidant enzymatic activities, glutathione reductase, and total and mitochondrial superoxide dismutase decreased in trained rats after I/R, whereas they remained unchanged in the sedentary ones. Ecto-5'-nucleotidase activity was modified by I/R in sedentary as well as in trained hearts while HSP72 content did not change. Ecto-5'-nucleotidase activity and HSP72 content increased in parallel by the 30-min perfusion period. In conclusion, the cardioprotection induced by long-term training could be mediated by the exercise-induced increase in HSP72 levels and is not related to enhanced antioxidant systems or ecto-5'-NT activity.

Sarcoplasmic reticulum and cardiac oxidative stress: an emerging target for heart disease

The sarcoplasmic reticulum (SR) is a major player in maintaining cardiac function, as it is intimately involved in the regulation of Ca2+-movements on a beat-to-beat basis. SR dysfunction due to abnormalities in SR protein content has been reported in different cardiac diseases such as ischaemic heart disease, myocardial infarction, congestive heart failure and various cardiomyopathies; thus the genes expressing the SR Ca2+-pump, Ca2+-channels, calsequestrin, phospholamban and other regulatory proteins are considered important targets for drug development. In our experience, ischaemic preconditioning (IP) and pharmacological therapies, such as anti-oxidants, beta-adrenergic receptor blockers, angiotensin receptor (AT-1) blockers, angiotensin converting enzyme inhibitors (ACE-I) and angiotensin receptor blockers are effective therapies that improve cardiac performance in the failing heart by improving SR function. Accordingly, this paper is intended to shed light on the knowledge in the field of cardiac therapy targeted to improve and protect SR function.

Upregulation of beta-adrenergic receptors in heart failure due to volume overload

To examine the mechanisms of changes in beta-adrenergic signal transduction in heart failing due to volume overload, we studied the status of beta-adrenoceptors (beta-ARs), G protein-coupled receptor kinase (GRK), and beta-arrestin in heart failure due to aortocaval shunt (AVS). Heart failure in rats was induced by creating AVS for 16 wk, and beta-AR binding, GRK activity, as well as their protein content, and mRNA levels were determined in both left and right ventricles. The density and protein content for beta1-ARs, unlike those for beta2-ARs, were increased in the failing hearts. Furthermore, protein contents for GRK isoforms and beta-arrestin-1 were decreased in membranous fractions and increased in cytosolic fractions from the failing hearts. On the other hand, steady-state mRNA levels for beta1-ARs and GRK2, as well as protein content for Gbetagamma-subunits, did not change in the failing heart. Basal cardiac function was depressed; however, both in vivo and ex vivo positive inotropic responses of the failing hearts to isoproterenol were augmented. Treatment of AVS animals with imidapril (1 mg.kg(-1).day(-1)) or losartan (20 mg.kg(-1).day(-1)) retarded the progression of heart failure; partially prevented changes in beta1-ARs, GRKs, and beta-arrestin-1 in the failing myocardium; and attenuated the increase in positive inotropic effect of isoproterenol. These results indicate that upregulation of beta1-ARs is associated with subcellular redistribution of GRKs and beta-arrestin-1 in the failing heart due to volume overload. Furthermore, attenuation of alterations in beta-adrenergic system by imidapril or losartan may be due to blockade of the renin-angiotensin system in the AVS model of heart failure.

Cardiovascular gene expression profiles of dioxin exposure in zebrafish embryos

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a widespread environmental contaminant that causes altered heart morphology, circulatory impairment, edema, hemorrhage, and early life stage mortality in fish. TCDD toxicity is dependent, in large part, on the aryl hydrocarbon receptor (AHR), but understanding of the molecular mechanism of cardiovascular embryotoxicity remains incomplete. To identify genes potentially involved in cardiovascular effects, we constructed custom cDNA microarrays consisting of 4896 zebrafish adult heart cDNA clones and over 200 genes with known developmental, toxicological and housekeeping roles. Gene expression profiles were obtained for 3-day-old zebrafish after early embryonic exposure to either 0.5 or 5.0 nM TCDD. In all, 516 clones were significantly differentially expressed (p < 0.005) under at least one treatment condition; 123 high-priority clones were selected for further investigation. Cytochromes P450 1A and 1B1, and other members of the AHR gene battery, were strongly and dose-dependently induced by TCDD. Importantly, altered expression of cardiac sarcomere components, including cardiac troponin T2 and multiple myosin isoforms, was consistent with the hypothesis that TCDD causes dilated cardiomyopathy. Observed increases in expression levels of mitochondrial energy transfer genes also may be related to cardiomyopathy. Other TCDD-responsive genes included fatty acid and steroid metabolism enzymes, ribosomal and signal-transduction proteins, and 18 expressed sequence tags (ESTs) with no known protein homologs. As the first broad-scale study of TCDD-modulated gene expression in a non-mammalian system, this work provides an important perspective on mechanisms of TCDD toxicity.

Alteration in some antioxidant enzymes in cardiac tissue upon monosodium glutamate [MSG] administration to adult male mice

4mg and 8mg monosodium glutamate per gram body weight was administered subcutaneously for 6 consecutive days to normal adult male mice and its effect was seen on 31(st) day after the last injection on some antioxidant enzymes in heart. A significant dose dependent increase in lipid peroxidation and xanthine oxidase level was observed, whereas the activity of free radical scavenging enzymes such as superoxide dismutase and catalase was decreased in both monosodium glutamate treated groups (Group-2 and Group-3). So, the present work suggested that monosodium glutamate at dose level of 4mg/g body weight and above induced oxidative stress in the cardiac tissue by changing the activity of free radical initiating enzyme such as xanthine oxidase and scavenging enzymes like superoxide dismutase and catalase.

HSP70 Binds to the Fast-twitch Skeletal Muscle Sarco(endo)plasmic Reticulum Ca2+-ATPase (SERCA1a) and Prevents Thermal Inactivation

This study examined whether HSP70 could bind to and protect against thermal inactivation of SERCA1a, the SERCA isoform expressed in adult fast-twitch skeletal muscle. Sarcoplasmic reticulum vesicles prepared from rat gastrocnemius muscle were incubated with purified HSP70 at both 37 and 41 degrees C for either 30, 60, or 120 min. Maximal SERCA1a activity (micromol/g protein/min) in the absence of HSP70 was reduced progressively with time, with greater reductions occurring at 41 degrees C compared with 37 degrees C. HSP70 protected against thermal inactivation of SERCA1a activity at 37 degrees C but not at 41 degrees C and only at 30 and 60 min but not at 120 min. HSP70 also protected against reductions in binding capacity for fluorescein isothiocyanate, a fluorescent probe that binds to Lys515 in the nucleotide binding domain of SERCA, at 30 and 60 min but not at 120 min, an effect that was independent of temperature. HEK-293 cells were co-transfected with cDNAs encoding rabbit SERCA1a and human HSP-EYFP and subjected to 40 degrees C for 1 h. Immunohistochemistry revealed nearly complete co-localization of SERCA1a with HSP70 under these conditions. Co-immunoprecipitation showed physical interaction between HSP70 and SERCA1a under all thermal conditions both in vitro and in HEK-293 cells. Modeling showed that the fluorescein isothiocyanate-binding site of intact SERCA1a in the E2 form lies in its close proximity to a potential interaction site between SERCA1a and HSP70. These results indicate that HSP70 can bind to SERCA1a and, depending on the severity of heat stress, protect SERCA1a function by stabilizing the nucleotide binding domain.

Inhibition of PLC improves postischemic recovery in isolated rat heart

The Ca2+-dependent PLC converts phosphatidylinositol 4,5-bisphosphate to diacylglycerol (DAG) and inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]. Because these products modulate Ca2+ movements in the myocardium, PLC may also contribute to a self-perpetuating cycle that exacerbates cardiomyocyte Ca2+-overload and subsequent cardiac dysfunction in ischemia-reperfusion (I/R). Although we have reported that I/R-induced changes in PLC isozymes might contribute to cardiac dysfunction, the present study was undertaken to examine the beneficial effects of the PLC inhibitor, U-73122, as well as determining the role of Ca2+ on the I/R-induced changes in PLC isozymes. Isolated rat hearts were subjected to global ischemia 30 min, followed by 5 or 30 min of reperfusion. Pretreatment of hearts with U-73122 (0.5 μM) significantly inhibited DAG and Ins(1,4,5)P3 production in I/R and was associated with enhanced recovery of cardiac function as indicated by measurement of left ventricular (LV) end-diastolic pressure (EDP), LV diastolic pressure (LVDP), maximum rate of pressure development (+dP/d tmax), and maximum rate of LV pressure decay (−dP/d tmax). Verapamil (0.1 μM) partially prevented the increase in sarcolemmal (SL) PLC-β1 activity in ischemia and the decrease in its activity during the reperfusion phase as well as elicited a partial protection of the depression in SL PLC-δ1 and PLC-γ1 activities during the ischemic phase and attenuated the increase during the reperfusion period. Although these changes were associated with an improved myocardial recovery after I/R, verapamil was less effective than U-73122. Perfusion with high Ca2+ resulted in the activation of the PLC isozymes studied and was associated with a markedly increased LVEDP and reduced LVDP, +dP/d tmax, and −dP/d tmax. These results suggest that inhibition of PLC improves myocardial recovery after I/R.

Vitamin C inhibits hypoxia-induced damage and apoptotic signaling pathways in cardiomyocytes and ischemic hearts

Reactive oxygen species play a central role in myocardial ischemic injury and are a target for therapeutic intervention. Vitamin C is an essential antioxidant yet difficult to deliver in pharmacologic concentration to the myocardium. We found that adult rat cardiomyocytes accumulate vitamin C by transporting dehydroascorbic acid (DHA), the oxidized form of vitamin C, but do not transport ascorbic acid. Loading cells with vitamin C by DHA treatment resulted in resistance to hypoxia- and hypoxia/reoxygenation-induced cell death associated with the quenching of reactive oxygen species. When rats were injected with DHA before coronary occlusion, the ascorbic acid content in the heart was six to eight times higher than in untreated controls and myocardial infarction was reduced by 62%. DHA also provided significant protection when administered intravenously 2 h after coronary occlusion. In cardiomyocytes subjected to hypoxia/reoxygenation, DHA treatment resulted in decreased apoptosis associated with inhibition of Bax expression, caspase-3 activation, and cytochrome c translocation into the cytoplasm. DHA treatment also inhibited Jak2, STAT1, and STAT5 phosphorylation, and increased STAT3 phosphorylation, in hypoxic cardiomyocytes and ischemic myocardial tissue. Our findings suggest that DHA may be useful as a cardioprotectant in ischemic heart disease.

Apheis: public health impact of PM10 in 19 European cities

STUDY OBJECTIVE

Apheis is a public health surveillance system that aims to provide European, national, regional, and local decision makers, environmental health professionals, and the general public with up to date and easy to use information on air pollution and public health. This study presents the health impact assessment done in 19 cities of Western and Eastern European countries.

DESIGN

Apheis developed guidelines for gathering and analysing data on air pollution and the impact on public health. Apheis has analysed the acute and chronic effects of fine particles on premature mortality using the estimates developed by Aphea2 study and two American cohort studies. This health impact assessment was performed for different scenarios on the health benefits of reducing levels of particles less than 10 microm in size (PM(10)).

MAIN RESULTS

PM(10) concentrations were measured in 19 cities (range: 14-73 microg/m(3)). The population covered in this health impact assessment includes nearly 32 million inhabitants. The age standardised mortality rates (per 100 000 people) range from 456 in Toulouse to 1127 in Bucharest. Reducing long term exposure to PM(10) concentrations by 5 microg/m(3) would have "prevented" between 3300 and 7700 early deaths annually, 500 to 1000 of which are associated with short term exposure.

CONCLUSIONS

Apheis shows that current levels of air pollution in urban Europe have a non-negligible impact on public health, and that preventive measures could reduce this impact, even in cities with low levels of air pollution.

Effect of edaravone, a novel free radical scavenger, on endothelium-dependent vasodilation in smokers

The forearm blood flow (FBF) responses to acetylcholine and to sodium nitroprusside were evaluated before and after administration of edaravone in 10 smokers and 10 nonsmokers. FBF response to acetylcholine was lower in smokers than in nonsmokers. The vasodilatory effects of sodium nitroprusside were similar in both groups. Co-infusion of edaravone increased the FBF response to acetylcholine in smokers, but did not affect the FBF response to acetylcholine in nonsmokers. The administration of N(G)-monomethyl-l-arginine abolished edaravone-induced augmentation of the FBF response to acetylcholine in smokers. The antioxidative agent edaravone increases nitric oxide mediated vasodilation through a decrease in oxidative stress.

Increased efflux of glutathione conjugate in acutely diabetic cardiomyocytes

In diabetes, cell death and resultant cardiomyopathy have been linked to oxidative stress and depletion of antioxidants like glutathione (GSH). Although the de novo synthesis and recycling of GSH have been extensively studied in the chronically diabetic heart, their contribution in modulating cardiac oxidative stress in acute diabetes has been largely ignored. Additionally, the possible contribution of cellular efflux in regulating GSH levels during diabetes is unknown. We used streptozotocin to make Wistar rats acutely diabetic and after 4 days examined the different processes that regulate cardiac GSH. Reduction in myocyte GSH in diabetic rats was accompanied by increased oxidative stress, excessive reactive oxygen species, and an elevated apoptotic cell death. The effect on GSH was not associated with any change in either synthesis or recycling, as both γ-glutamylcysteine synthetase gene expression (responsible for bio syn thesis) and glutathione reductase activity (involved with GSH recycling) remained unchanged. However, gene expression of multidrug resistance protein 1, a transporter implicated in effluxing GSH during oxidative stress, was elevated. GSH conjugate efflux mediated by multidrug resistance protein 1 also increased in diabetic cardiomyocytes, an effect that was blocked using MK-571, a specific inhibitor of this transporter. As MK-571 also decreased oxidative stress in diabetic cardiomyocytes, an important role can be proposed for this transporter in GSH and reactive oxygen species homeostasis in the acutely diabetic heart. Key words: cardiomyocytes, apoptosis, multidrug resistance protein, reactive oxygen species.

Role of oxidative stress in ischemia-reperfusion-induced changes in Na+,K(+)-ATPase isoform expression in rat heart

The aim of this study was to assess whether depression of cardiac Na+,K(+)-ATPase activity during ischemia/reperfusion (I/R) is associated with alterations in Na+,K(+)-ATPase isoforms, and if oxidative stress participates in these I/R-induced changes. Na+,K(+)-ATPase alpha1, alpha2, alpha3, beta1, beta2, and beta3 isoform contents were measured in isolated rat hearts subjected to I/R (30 min of global ischemia followed by 60 min of reperfusion) in the presence or absence of superoxide dismutase plus catalase (SOD+CAT). Effects of oxidative stress on Na+,K(+)-ATPase isoforms were also examined by perfusing the hearts for 20 min with 300 microM hydrogen peroxide or 2 mM xanthine plus 0.03 U/ml xanthine oxidase (XXO). I/R significantly reduced the protein levels of all alpha and beta isoforms. Treatment of I/R hearts with SOD+CAT preserved the levels of alpha2, alpha3, beta1, beta2, and beta3 isoforms, but not that of the alpha1 isoform. Perfusion of hearts with hydrogen peroxide and XXO depressed all Na+,K(+)-ATPase alpha and beta isoforms, except for alpha1. These results indicate that the I/R-induced decrease in Na+,K(+)-ATPase may be due to changes in Na+,K(+)-ATPase isoform expression and that oxidative stress plays a role in this alteration. Antioxidant treatment attenuated the I/R-induced changes in expression of all isoforms except alpha1, which appears to be more resistant to oxidative stress.

Superoxide dismutase, catalase and glutathione peroxidase in the spontaneously hypertensive rat kidney

BACKGROUND AND OBJECTIVE

Earlier studies have shown increased production of reactive oxygen species (ROS) and upregulation of ROS-generating enzyme, nicotinamide adenine dinucleotide (phosphate) oxidase, in the kidney of spontaneously hypertensive rats (SHR). This study aimed to examine the activities and protein abundance of the main antioxidant enzymes [i.e. superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX)] in the kidney of SHR fed a regular or an antioxidant-rich diet.

METHODS

Pregnant SHR and their offspring were fed either a regular diet or an antioxidant-rich diet (alpha-tocopherol, ascorbic acid, zinc and selenium) and observed for 6 months. Wistar-Kyoto (WKY) rats fed a regular or antioxidant-fortified diet served as controls.

RESULTS

The untreated SHR showed severe hypertension and significant increases in plasma hydrogen peroxide and renal tissue nitrotyrosine abundance, indicating the presence of oxidative/nitrosative stress. Despite oxidative stress, Cu Zn SOD, CAT and GPX activities were unchanged in the cortex and medulla of untreated SHR. Immunodetectable Mn SOD was reduced in the medulla and elevated in the cortex, whereas, Cu Zn SOD protein was unchanged in the cortex and reduced in the medulla. By contrast, CAT protein abundance was increased in both cortex and medulla while GPX protein was elevated in the cortex and unchanged in the medulla. Comparison of protein abundance and activities of the antioxidant enzymes revealed significant discordance in the untreated SHR. Lifelong antioxidant therapy diminished the severity of hypertension, improved oxidative stress and ameliorated or reversed abnormalities of antioxidant enzyme expressions and activities. By contrast, antioxidant therapy had no effect on the measured parameters in the WKY rat controls.

CONCLUSIONS

Oxidative stress in SHR was associated with a lack of coordinate upregulation of the antioxidant enzymes and discordance between their protein abundance and enzymatic activity. These findings suggest an impaired antioxidant defense system and the presence of functionally abnormal enzymes in the SHR kidney. Lifelong antioxidant therapy improved expression, activity and activity-to-mass relationship of the measured enzymes. The latter suggests oxidative and nitrosative modification of these molecules in the SHR kidney.

Endothelium-Targeted Gene and Cell-Based Therapies for Cardiovascular Disease

Most common cardiovascular diseases are accompanied by endothelial dysfunction. Because of its predominant role in the pathogenesis of cardiovascular disease, the vascular endothelium is an attractive therapeutic target. The identification of promoter sequences capable of rendering endothelial-specific transgene expression together with the recent development of vectors with enhanced tropism for endothelium may offer opportunities for the design of new strategies for modulation of endothelial function. Such strategies may be useful in the treatment of chronic diseases such as hypertension, atherosclerosis, and ischemic artery disease, as well as in acute myocardial infarction and during open heart surgery for prevention of ischemia and reperfusion (I/R)-induced injury. The recent identification of putative endothelial progenitor cells in peripheral blood may allow the design of autologous cell-based strategies for neovascularization of ischemic tissues and for the repair of injured blood vessels and bioengineering of vascular prosthesis. "Proof-of-concept" for some of these strategies has been established in animal models of cardiovascular disease. However the successful translation of these novel strategies into clinical application will require further developments in vector and delivery technologies. Further characterization of the processes involved in mobilization, migration, homing, and incorporation of endothelial progenitor cells into the target tissues is necessary, and the optimal conditions for therapeutic application of these cells need to be defined and standardized.

Reactive oxygen species in vascular biology: implications in hypertension

Reactive oxygen species (ROS), including superoxide (*O2-), hydrogen peroxide (H2O2), and hydroxyl anion (OH-), and reactive nitrogen species, such as nitric oxide (NO) and peroxynitrite (ONOO-), are biologically important O2 derivatives that are increasingly recognized to be important in vascular biology through their oxidation/reduction (redox) potential. All vascular cell types (endothelial cells, vascular smooth muscle cells, and adventitial fibroblasts) produce ROS, primarily via cell membrane-associated NAD(P)H oxidase. Reactive oxygen species regulate vascular function by modulating cell growth, apoptosis/anoikis, migration, inflammation, secretion, and extracellular matrix protein production. An imbalance in redox state where pro-oxidants overwhelm anti-oxidant capacity results in oxidative stress. Oxidative stress and associated oxidative damage are mediators of vascular injury and inflammation in many cardiovascular diseases, including hypertension, hyperlipidemia, and diabetes. Increased generation of ROS has been demonstrated in experimental and human hypertension. Anti-oxidants and agents that interrupt NAD(P)H oxidase-driven *O2- production regress vascular remodeling, improve endothelial function, reduce inflammation, and decrease blood pressure in hypertensive models. This experimental evidence has evoked considerable interest because of the possibilities that therapies targeted against reactive oxygen intermediates, by decreasing generation of ROS and/or by increasing availability of antioxidants, may be useful in minimizing vascular injury and hypertensive end organ damage. The present chapter focuses on the importance of ROS in vascular biology and discusses the role of oxidative stress in vascular damage in hypertension.

A gallic acid derivative and polysaccharides with antioxidative activity from rose (Rosa rugosa) flowers

In this study, the major antioxidant components of rose flower were identified. An aqueous extract of rose flowers was chromatographed on CM-cellulose in ammonium acetate buffer (10 mM, pH 4.5) to yield three un-adsorbed peaks F1, F2 and F3. Each of these peaks was subjected to gel filtration on Sephadex G75. F1 yielded two peaks, whereas both F2 and F3 gave rise to only a single peak. Spectroscopic studies using NMR and FTIR revealed that F3 is a gallic acid derivative. It exhibited the highest antioxidative potency. F1-a derived from F1 by gel filtration is mainly a polysaccharide-peptide complex with less potent antioxidative activity. F2 is a polysaccharide also with reduced antioxidant activity. This study demonstrates, for the first time, the presence of both gallic acid derivatives and polysaccharides as major antioxidant principles of the aqueous extract of rose flowers.

Application of gas chromatography-mass spectrometry for analysis of isoprostanes: their role in cardiovascular disease

Cardiovascular disease (CVD) is the major cause of death in the Western hemisphere. Oxidative stress is involved in the pathophysiology of cancer, neurodegenerative conditions and CVD. Lipid peroxidation is one of the oxidative modifications possible in biological systems. The isoprostanes are derivatives of one specific lipid, i.e., arachidonic acid, after lipid peroxidation. Several isoprostanes have been identified in biological tissues and fluids, among them 8-iso prostaglandin F2alpha (8-iso-PGF2alpha, 8-epi-PGF2alpha, iPF2alpha-III, 15-F2t-IsoP) and its metabolite, 2,3-dinor-4,5-dihydro-8-iso-PGF2alpha. The isoprostanes are reliable in vivo markers of lipid peroxidation in humans: they are endogenously formed, characteristic in structure, ubiquitous in nature, stable in- and ex vivo and reliably quantitatable. In this Review, different analytical approaches will be discussed including immunologic, chromatographic and spectrometric techniques with the main emphasis on mass spectrometry. Analysis of isoprostanes applying radio immunoassay (RIA), enzyme immunoassay (EIA), high performance-liquid chromatography (HPLC), liquid chromatography-tandem mass spectrometry (LC-tandem MS), gas chromatography-mass spectrometry (GC-MS) and GC-tandem MS will be exemplified in the field of cardiovascular research. Results from several clinical studies are included indicating the validity of isoprostanes as surrogate parameters of oxidative stress in cardiovascular disease.

Streptozotocin directly impairs cardiac contractile function in isolated ventricular myocytes via a p38 map kinase-dependent oxidative stress mechanism

Streptozotocin (STZ) has long been used to induce experimental diabetes mellitus to study diabetic complications such as diabetic cardiomyopathy. However, direct impact of STZ on cardiac function is unknown. This study was designed to evaluate the cardiac contractile effect of STZ in isolated adult rat ventricular myocytes. Contractile properties were assessed with an IonOptix MyoCam system including peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR90), and maximal velocities of shortening/relengthening (+/-dL/dt). Intracellular Ca2+ handling was evaluated with the fluorescent dye fura-2. Acute exposure of STZ (10(-9)-10(-5) M) depressed PS, prolonged TR90, and decreased electrically stimulated intracellular Ca2+ rise in a concentration-dependent manner. TPS,+/-dL/dt, resting intracellular Ca2+ level, and intracellular Ca2+ clearing rate were unaffected. The STZ-induced mechanical alterations were alleviated by the antioxidant vitamin C (100 microM) and the p38 MAP kinase inhibitor SB203580 (1 microM). 2', 7'-Dichlorofluorescein diacetate staining revealed enhanced production of reactive oxygen species following STZ treatment, which was prevented by either vitamin C or SB203580. Collectively, our data provided convincing evidence that the tool drug for experimental diabetes STZ may itself cause deleterious cardiac contractile dysfunction via an oxidative stress and p38 MAP kinase-dependent mechanism. Thus, caution should be taken when assessing diabetic heart complications using STZ-induced diabetic models.

Reactive oxygen species mediate Endothelin-1-induced activation of ERK1/2, PKB, and Pyk2 signaling, as well as protein synthesis, in vascular smooth muscle cells

Reactive oxygen species (ROS) have been shown to mediate the effects of several growth factors and vasoactive peptides, such as epidermal growth factor, platelet-derived growth factor, and angiotensin II (AII). Endothelin-1 (ET-1) is a vasoactive peptide which also exhibits mitogenic activity in vascular smooth muscle cells (VSMCs), and is believed to contribute to the pathogenesis of vascular abnormalities such as atherosclerosis, hypertension, and restenosis after angioplasty. However, a possible role for ROS generation in mediating the ET-1 response on extracellular signal-regulated kinases 1 and 2 (ERK1/2), protein kinase B (PKB), and protein tyrosine kinase 2 (Pyk2), key components of the growth-promoting and proliferative signaling pathways, has not been examined in detail. Our aim was to investigate the involvement of ROS in ET-1-mediated activation of ERK1/2, PKB, and Pyk2 in A-10 VSMCs. ET-1 stimulated ERK1/2, PKB, and Pyk2 phosphorylation in a dose- and time-dependent manner. Pretreatment of A-10 VSMCs with diphenyleneiodonium (DPI), an inhibitor of reduced nicotinamide adenine dinucleotide phosphate oxidase, attenuated ET-1-enhanced ERK1/2, PKB, and Pyk2 phosphorylation. In addition, in parallel with an inhibitory effect on the above signaling components, DPI also blocked ET-1-induced protein synthesis. ET-1 was also found to increase ROS production, which was suppressed by DPI treatment. N-Acetylcysteine, a ROS scavenger, exhibited a response similar to that of DPI and inhibited ET-1-stimulated ERK1/2, PKB, and Pyk2 phosphorylation. These results demonstrate that ROS are critical mediators of ET-1-induced signaling events linked to growth-promoting proliferative and hypertrophic pathways in VSMCs.

Effect of manidipine on gene expression and protein level of oxidative stress-related proteins: p22phox and HO-1: relevance for antihypertensive and anti-remodeling effects

Oxidative stress (OxSt) is a major damaging factor in arterial hypertension and its long-term complications. This is why considerable attention is paid to the possible effects of antihypertensive drugs on OxSt. Manidipine is a dihydropiridine calcium channel blocker with reported nephroprotective activities, but no information is available on its effect on OxSt and related mechanisms. This study assessed the effect of manidipine on normal subjects' monocyte gene and protein expression of OxSt-related proteins such as p22(phox), a NAD(P)H oxidase system subunit, critical in generating O2-, and heme oxygenase-1 (HO-1), induced by and protective from OxSt, and compared manidipine with the ACE inhibitor captopril and the calcium channel blocker nifedipine, in the presence and absence of sodium arsenite (NaAsO2) as an inducer of OxSt.Co-incubation of manidipine with NaAsO2 dose-dependently decreased p22(phox) mRNA production from basal: 0.87 +/- 0.1 d.u., 0.69 +/- 0.06 and 0.66 +/- 0.09 at 100, 300 and 500 nM respectively versus 0.99 +/- 0.2, P < 0.04, while HO-1 mRNA production was increased by the same concentrations of the drug: 0.87 +/- 0.1 d.u., 0.92 +/- 0.1, 0.98 +/- 0.1 respectively versus 0.63 +/- 0.07; P < 0.03. Monocyte p22(phox) mRNA production was reduced both by manidipine and captopril: 0.48 +/- 0.04 d.u. and 0.43 +/- 0.08, respectively versus 0.58 +/- 0.07, P < 0.006, while no changes were induced by nifedipine (0.61 +/- 0.07, P = ns). Manidipine increased monocyte HO-1 mRNA production (1.6 +/- 0.4 versus 1.2 +/- 0.4, P < 0.008), while nifedipine and captopril showed no effect (1.2 +/- 0.3 and 1.1 +/- 0.3, respectively). The effects of M on p22(phox) and HO-1 gene expression in the presence of OxSt were also paralleled by the same effects at protein level. In conclusion, manidipine decreases p22(phox) and increases HO-1 mRNA production and protein level. The manidipine-induced increase of HO-1 gene and protein expression seems to be a peculiar effect of this drug since it is not observed with captopril and nifedipine. This effect, together with the reduction of p22(phox) mRNA production, could play a role in its protective mechanism against OxSt.

Correlation of NO metabolites and 8-iso-prostaglandin F2a with periventricular hyperintensity severity

OBJECTIVE

Oxidative stress and NO are thought to play important roles in arteriosclerosis pathogenesis, a major cause of white matter lesions in the brain. Therefore, we examined whether NO metabolites (NOx) and 8-iso-prostaglandin F(2alpha) (IsoP) levels in vivo correlated with the severity of periventricular hyperintensity (PVH) to evaluate potential roles of oxidative stress and NO in white matter lesions.

METHODS AND RESULTS

Participants (687 males and 528 females) of a health-screening examination were recruited into the study. The plasma NOx and urinary IsoP levels were measured using the Griess method and ELISA, respectively. PVH was diagnosed on the basis of MRIs. In nonparametric univariate trend analyses, plasma NOx as well as aging, presence of hypertension and of lacunes, mean blood pressure, and high-density lipoprotein cholesterol showed highly significant monotone correlation with PVH severity (P</=0.01). By the multivariate ordinal regression analysis, the plasma NOx (P=0.002) and urinary IsoP (P=0.01) levels were found to be independent factors influencing the severity of PVH together with aging (P<0.001), presence of hypertension (P<0.001) and lacunes (P<0.001), and mean blood pressure (P=0.001).

CONCLUSIONS

Oxidative stress and NO have a close correlation with PVH severity. Oxidative stress and NO levels were evaluated in a general population with or without mild periventricular hyperintensity under a cross-sectional study design. Serum NOx (NO metabolites) and urinary 8-iso-PG F2alpha (a marker for oxidative stress) correlated with the severity of periventricular hyperintensity in a multivariate analysis.

Oxidative stress: a theoretical model or a biological reality?

Although oxidative stress has been extensively studied the last fifteen years, many physicians and biologists are still sceptical concerning its interest in biology and medicine. This is probably due, in part, to the fact that this subject is a matter of biophysics, and the first studies reported were written using a physical language that inspired these people used to a more concrete problematic very little. Another problem is the difficulty to detect the species mediating oxidative stress, and to determine their role in biological processes. This review is aimed at presenting oxidative stress, as well as reactive oxygen species and free radicals--the molecules that mediate it--in a clear form able to convince all researchers involved in life sciences that these short-lived intermediates are indissociable from any aerobic organism. Moreover, if reactive oxygen species and free radicals are undoubtedly involved in many pathologies, they have physiological functions too.

Reduced myocardial ischemia-reperfusion injury in toll-like receptor 4-deficient mice

BACKGROUND

Myocardial ischemia and reperfusion-induced tissue injury involve a robust inflammatory response, but the proximal events in reperfusion injury remain incompletely defined. Toll-like receptor 4 (TLR4) is a proximal signaling receptor in innate immune responses to lipopolysaccharide of Gram-negative pathogens. TLR4 is also expressed in the heart and vasculature, but a role for TLR4 in the myocardial response to injury separate from microbial pathogens has not been examined. This study assessed the role of TLR4 in myocardial infarction and inflammation in a murine model of ischemia-reperfusion injury.

METHODS AND RESULTS

Myocardial ischemia-reperfusion (MIR) was performed on 2 strains of TLR4-deficient mice (C57/BL10 ScCr and C3H/HeJ) and controls (C57/BL10 ScSn and C3H/OuJ). Mice were subjected to 1 hour of coronary ligation, followed by 24 hours of reperfusion. TLR4-deficient mice sustained significantly smaller infarctions compared with control mice given similar areas at risk. Fewer neutrophils infiltrated the myocardium of TLR4-deficient Cr mice after MIR, indicated by less myeloperoxidase activity and fewer CD45/GR1-positive cells. The myocardium of TLR4-deficient Cr mice contained fewer lipid peroxides and less complement deposition compared with control mice after MIR. Serum levels of interleukin-12, interferon-gamma, and endotoxin were not increased after ischemia-reperfusion. Neutrophil trafficking in the peritoneum was similar in all strains after injection of thioglycollate.

CONCLUSIONS

TLR4-deficient mice sustain smaller infarctions and exhibit less inflammation after myocardial ischemia-reperfusion injury. The data suggest that in addition to its role in innate immune responses, TLR4 serves a proinflammatory role in murine myocardial ischemia-reperfusion injury.

The effects of iron dextran on the oxidative stress in cardiovascular tissues of rats with chronic renal failure

BACKGROUND

Redox-active iron can promote oxidative stress and tissue injury by catalyzing hydroxyl radical generation and lipid peroxidation. Intravenous iron preparations are routinely administered in conjunction with erythropoietin to treat anemia in patients with chronic renal failure (CRF), a condition that is marked by oxidative stress and inflammation. This treatment frequently elevates iron burden, which can potentially intensify oxidative stress and, thus, cardiovascular disease in this population.

METHODS

We studied renal function and oxidative stress parameters in the cardiovascular tissues of CRF (5/6 nephrectomized) and sham-operated control rats 3 months after a single intravenous infusion of iron dextran (500 mg/kg).

RESULTS

Arterial pressure was equally elevated and creatinine clearance was equally reduced in both iron-treated and -untreated CRF groups. Iron administration significantly raised the blood hemoglobin, serum iron concentration, and transferrin saturation in both CRF and control groups. Iron administration resulted in a significant rise in plasma concentration of lipid peroxidation product, malondialdehyde in the CRF rats, and an insignificant rise in the control group. Plasma oxidized low-density lipoprotein (LDL) concentration was increased in the CRF groups, and was not affected by iron administrations. Iron administration raised nitrotyrosine abundance in the aorta of CRF but not in the control group. Left ventricular tissue abundance of p22(phox) subunit of NAD(P)H oxidase was elevated in CRF group and was not affected, whereas p67(phox) subunit abundance was raised by prior iron administration. Iron administration insignificantly lowered aorta p22(phox), but had no effect on p67(phox) subunit abundance in the treated CRF group. Previous iron administration significantly lowered superoxide dismutase and catalase abundance in the aorta and glutathione peroxidase in the left ventricle of CRF animals, but did not significantly change these parameters in the iron-treated control animals.

CONCLUSION

A single intravenous injection of iron dextran increased oxidative stress in the cardiovascular tissues in the CRF group, but not the control rats, pointing to heightened susceptibility to iron-mediated toxicity in CRF. However, administration of iron dextran did not adversely affect kidney function, and favorably affected hemoglobin concentration in rats with CRF induced by renal mass reduction. Further studies are needed to explore the effects of other parenteral iron preparations, repeated intravenous iron administration, and presence of comorbid conditions such as diabetes.

Homocysteine and essential hypertension

The authors examine the available clinical and experimental data supporting the view that homocysteine, an alternative risk factor of cardiovascular disease, may play a role in the pathogenesis of essential hypertension. The mechanism of this disease has not been elucidated, but it may be related to impairment of vascular endothelial and smooth muscle cell function. Therefore, the occurrence of endothelial dysfunction could contribute to alterations of the endothelium-dependent vasomotor regulation. Elevated homocysteinemia diminishes the vasodilation by nitric oxide, increases oxidative stress, stimulates the proliferation of vascular smooth muscle cells, and alters the elastic properties of the vascular wall. Thus, homocysteine contributes to elevate the blood pressure. Also it is known that elevated plasma levels of homocysteine could lead to oxidant injury to the endothelium. The correction of elevated homocysteinemia by administration of vitamins B12 and B6 plus folic acid, could be a useful adjuvant therapy of hypertension. However, further controlled randomized trials are necessary to establish the efficacy and tolerability of these potentially therapeutic agents.

Role of reactive oxygen species in ischemic preconditioning of subcellular organelles in the heart

Ischemic preconditioning (IPC) is an endogenous adaptive mechanism and is manifested by early and delayed phases of cardioprotection. Brief episodes of ischemia-reperfusion during IPC cause some subtle functional and structural alterations in sarcolemma, mitochondria, sarcoplasmic reticulum, myofibrils, glycocalyx, as well as nucleus, which render these subcellular organelles resistant to subsequent sustained ischemia-reperfusion insult. These changes occur in functional groups of various receptors, cation transporters, cation channels, and contractile and other proteins, and may explain the initial effects of IPC. On the other hand, induction of various transcriptional factors occurs to alter gene expression and structural changes in subcellular organelles and may be responsible for the delayed effects of IPC. Reactive oxygen species (ROS), which are formed during the IPC period, may cause these changes directly and indirectly and act as a trigger of IPC-induced cardioprotection. As ROS may be one of the several triggers proposed for IPC, this discussion is focused on the current knowledge of both ROS-dependent and ROS-independent mechanisms of IPC. Furthermore, some events, which are related to functional preservation of subcellular organelles, are described for a better understanding of the IPC phenomenon.

Distinct roles of Ca2+, calmodulin, and protein kinase C in H2O2-induced activation of ERK1/2, p38 MAPK, and protein kinase B signaling in vascular smooth muscle cells

We have shown earlier that extracellular signal-regulated kinases 1 and 2 (ERK1/2) and protein kinase B (PKB), two key mediators of growth-promoting and proliferative responses, are activated by hydrogen peroxide (H(2)O(2)) in A10 vascular smooth muscle cells (VSMC). In the present studies, using a series of pharmacological inhibitors, we explored the upstream mechanisms responsible for their activation in response to H(2)O(2). H(2)O(2) treatment of VSMC stimulated ERK1/2, p38 mitogen-activated protein kinase (MAPK), and PKB phosphorylation in a dose- and time-dependent fashion. BAPTA-AM and EGTA, chelators of intracellular and extracellular Ca(2+), respectively, inhibited H(2)O(2)-stimulated ERK1/2, p38 MAPK, and PKB phosphorylation. Fluphenazine, an antagonist of the Ca(2+)-binding protein calmodulin, also suppressed the enhanced phosphorylation of ERK1/2, p38 MAPK, and PKB. In contrast, the protein kinase C (PKC) inhibitors Gö 6983 and Rö 31-8220 attenuated H(2)O(2)-induced ERK1/2 phosphorylation, but had no effect on p38 MAPK and PKB phosphorylation. Taken together, these data demonstrate that the activation of Ca(2+)/calmodulin-dependent pathways represents a key component mediating the stimulatory action of H(2)O(2) on ERK1/2, p38 MAPK, and PKB phosphorylation. On the other hand, PKC appears to be an upstream modulator of the increased ERK1/2 phosphorylation, but not of p38 MAPK and PKB in response to H(2)O(2) in VSMC.

High levels of myocardial antioxidant defense in aging nondiabetic normotensive Zucker obese rats

Chronic renal failure often induces left ventricular hypertrophy. We assessed whether the heart is affected in the Zucker obese rat, a model of chronic renal failure associated with obesity, glucose intolerance, and insulin resistance without hypertension or hyperglycemia. After systemic blood pressure measurement, the heart, the aorta, and the kidneys were removed from anesthetized 9- and 13-mo-old Zucker obese and lean control male rats ( n = 33, n = 24, n = 25, and n = 21, respectively). Determination of left ventricular geometry, quantification of myocardium collagen density, and measurement of heart antioxidant enzyme activity were made, as well as aorta and kidney parameters. Mean blood pressure remained at a normal range whatever the age and group considered. Whereas kidney structure and function were severely impaired, no sign of myocardial infarction or inflammatory process was noticed. A moderate left ventricular hypertrophy was observed in 13-mo-old obese rats. While heart malondialdehyde was stable with age and among groups, antioxidant enzyme activity was higher in obese rats. In conclusion, in the absence of hypertensive or hyperglycemic disorders, the heart seems to display a sufficient line of defense against oxidative stress during the development of cardiac hypertrophy.

Vitamin C improves attenuated angiotensin II-induced endothelium-dependent vasodilation in human forearm vessels

Endothelial dysfunction might be related to an increase in superoxide anion production in patients with hypertension, hypercholesterolemia, diabetes mellitus, and heart failure. Studies in animal models indicate that angiotensin II increases superoxide anion production by vascular tissues. We examined whether angiotensin II attenuates endothelium-dependent vasodilation via an increase in superoxide anion production in human forearm vessels in vivo. Forearm blood flow was measured in 23 healthy young men. We examined forearm vasodilator responses to an intra-arterial infusion of acetylcholine (4, 8, and 16 microg/min) and sodium nitroprusside (0.8, 1.6, and 3.2 microg/min) before and during an intra-arterial infusion of anglotensin II (n=8), angiotensin II plus vitamin C (n=8), and vitamin C alone (n=4). Angiotensin II attenuated the forearm vasodilatory response to acetylcholine (p<0.05), and this attenuated response was abolished by vitamin C. Angiotensin II did not alter the forearm vasodilatory response to sodium nitroprusside, and vitamin C infusion did not affect the forearm vasodilatory response to either acetylcholine or sodium nitroprusside. The forearm vasodilator response to acetylcholine did not change during infusion of norepinephrine (n=3), which reduced forearm blood flow to a degree similar to that by angiotensin II infusion. These results suggest that angiotensin II attenuates endothelium-dependent forearm vasodilation, and vitamin C improves this impairment. Thus, angiotensin II likely attenuates endothelium-dependent vasodilation via an increase of superoxide anion production in the human forearm in vivo.

Implications of oxidative stress and homocysteine in the pathophysiology of essential hypertension

The present review examines the clinical and experimental data to support the view that homocysteine and oxidative stress, two alternative risk factors of vascular disease, may play a role in the pathogenesis of primary or essential hypertension. Although the precise mechanism of this disease has not been elucidated, it may be related to impairment of vascular endothelial and smooth muscle cell function. Thus, the occurrence of endothelial dysfunction could contribute to alterations of the endothelium-dependent vasomotor regulation. Hyperhomocysteinemia limits the bioavailability of nitric oxide, increases oxidative stress, stimulates the proliferation of vascular smooth muscle cells, and alters the elastic properties of the vascular wall. The link between oxidative stress and hyperhomocysteinemia is also biologically plausible, because homocysteine promotes oxidant injury to the endothelium. Cumulated evidence suggests that the diminution of oxidative stress with antioxidants or the correction of hyperhomocysteinemia with vitamins-B plus folic acid, could be useful as an adjuvant therapy for essential hypertension. Further studies involving long-term trials could help to assess the tolerability and efficacy of the use of these therapeutic agents.

Urinary 8-iso-prostaglandin F2alpha as a risk marker in patients with coronary heart disease: a matched case-control study

BACKGROUND

Oxidative stress is involved in the pathophysiology of atherosclerosis, diabetes mellitus, hypertension, obesity, and cigarette smoking, all of these being risk factors for coronary heart disease (CHD). We tested the hypothesis that risk factors of CHD are associated with abundant systemic oxidative stress.

METHODS AND RESULTS

We conducted a case-control study with 93 CHD patients and 93 control subjects frequency-matched by age and sex. Urinary excretion of the F2-isoprostane 8-iso-prostaglandin (PG) F2alpha and its major urinary metabolite, 2,3-dinor-5,6-dihydro-8-iso-PGF2alpha, were measured by gas chromatography-tandem mass spectrometry. Body mass index, systolic blood pressure, and C-reactive protein were elevated in CHD patients (P<0.01). Urinary 8-iso-PGF2alpha and 2,3-dinor-5,6-dihydro-8-iso-PGF2alpha also differed, from 77 (interquartile range, 61-101) to 139 (93-231) pmol/mmol creatinine and from 120 (91-151) to 193 (140-275) pmol/mmol in control subjects and case subjects, respectively (P<0.001). 8-iso-PGF2alpha and its metabolite were highly correlated (Spearman's rho=0.664, P<0.001). HDL cholesterol was diminished in CHD patients (P<0.001). All of these characteristics predicted CHD in univariate analysis. In a multivariate model, the odds ratios were increased only for 8-iso-PGF2alpha (> or =131 pmol/mmol, P<0.001) and C-reactive protein (>3 mg/L, P<0.01), ie, by 30.8 (95% CI, 7.7-124) and 7.2 (1.9-27.6), respectively. 8-iso-PGF2alpha was found to be a novel marker in addition to known risk factors of CHD, ie, diabetes mellitus, hypercholesterolemia, hypertension, and smoking. Urinary excretion of 8-iso-PGF2alpha correlated with the number of risk factors for all subjects (P<0.001 for trend).

CONCLUSIONS

8-iso-PGF2alpha is a sensitive and independent risk marker of CHD.

Redox status and lipid peroxidation in alcoholic hypertensive patients and alcoholic hypertensive patients with diabetes

BACKGROUND

Free radical-mediated oxidative stress has been implicated in the progression of alcoholic hypertension and diabetic hypertension.

METHODS

The lipid peroxides and antioxidant status of plasma and erythrocytes were investigated in alcoholic hypertensive patients and alcoholic hypertensive patients with diabetes and compared with normal subjects.

RESULTS

A significant increase is observed in the levels of glucose, lipid peroxidation (P<0.05) in the alcoholic hypertensive patients with/without diabetes and the increase was significantly higher in alcoholic hypertensive patients with diabetes. The activities of erythrocyte antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and reduced glutathione (GSH) and plasma concentrations of GSH, vitamin C, vitamin E and beta-carotene decreased significantly and the level of ceruloplasmin increased in alcoholic hypertensive patients with/without diabetes when compared to normal subjects. Plasma GSH and vitamin E levels exhibited a further decrease in alcoholic hypertensive patients with diabetes.

CONCLUSIONS

An enhanced lipid peroxidation is observed in alcoholic hypertensive patients with diabetes and a more pronounced decrease in the levels of plasma GSH and vitamin E among antioxidants.

Oxidative stress - a link between endothelial injury, coagulation activation, and atherosclerosis in haemodialysis patients

BACKGROUND/AIM

Recently emerging evidence suggests that oxidative stress (SOX) may participate in atherogenesis. The aim of the present study was to establish whether enhanced SOX, involving endothelial injury, activation of coagulation, and inflammatory reaction, could be implicated in atherosclerotic diseases in haemodialysis (HD) patients.

METHODS

Markers of SOX, endothelial injury, coagulation, and cytokines, were measured in the plasma of HD patients with and without cardiovascular disease (CVD), and of healthy controls by ELISA methods. Remodeling of the carotid arteries was assessed by measuring the intima-media thickness (IMT) as a surrogate of atherosclerotic disease in all groups.

RESULTS

Markers of SOX, endothelial injury, and extrinsic coagulation pathway activation and IMT values were significantly elevated in HD patients, especially in those with CVD when compared with the control group. The von Willebrand factor antigen (vWF:Ag) levels were more increased in the patients with CVD than in those without. Furthermore, the plasma levels of tumour necrosis factor alpha, monocyte chemo-attractant protein 1, and macrophage inflammatory protein 1 beta were significantly higher only in the HD group with CVD when compared with the controls. The IMT was strongly and directly correlated with Cu/Zn superoxide dismutase. Both IMT and Cu/Zn superoxide dismutase were positively correlated with age, thrombomodulin, vWF:Ag, tissue factor, tissue factor pathway inhibitor, prothrombin fragment F1 + 2, monocte chemo-attractant protein 1, macrophage inflammatory protein 1 beta, and tumour necrosis factor alpha levels. Multivariate analysis identified vWF:Ag as the only independent variable significantly associated with an increased IMT.

CONCLUSIONS

The present study suggests that enhanced SOX, involved pro-atherogenic cytokine and chemokines levels, endothelial injury, and coagulation activation may constitute a pathway for accelerated atherosclerosis in HD patients. The significant, independent association between IMT and vWF:Ag should be assessed in future studies to determine whether vWF:Ag elevation is causative or a by-product of the increased IMT.

Up-regulation of kidney NAD(P)H oxidase and calcineurin in SHR: Reversal by lifelong antioxidant supplementation

BACKGROUND

Spontaneously hypertensive rats (SHR) are born normotensive and develop hypertension (HTN) later in life (age 4 to 5 weeks). HTN in SHR is associated with and caused in part, by oxidative stress and renal interstitial inflammation. This study tested the hypothesis that lifelong antioxidant supplementation beginning at prenatal period may delay the onset and reduce the severity of HTN in SHR. The study further sought to explore the effect of diet modification on renal tissue NAD(P)H oxidase and calcineurin abundance.

METHODS

Pregnant SHR and their offspring were fed either an antioxidant-fortified diet (a chow containing alpha-tocopherol 5000 IU/kg, ascorbic acid 500 ppm, selenium 2.76 ppm, and zinc 350 ppm) or regular diet (alpha-tocopherol 40 IU/kg, selenium 0.2 ppm, and zinc 70 ppm). Animals were observed for 24 weeks. Wistar-Kyoto rats fed either a regular or antioxidant diet served as control.

RESULTS

Onset of HTN was delayed and severity of HTN was reduced in antioxidant-treated compared with untreated SHR. Markers of oxidative stress (i.e., plasma hydrogen peroxide, renal tissue malondialdehyde, and nitrotyrosine abundance) were elevated in untreated but not in antioxidant-treated SHR. gp91phox and p22phox subunits of NAD(P)H oxidase were markedly elevated in the renal cortex of untreated SHR and partially restored in the treated SHR. Similarly, renal calcineurin Aalpha and B subunits were elevated in untreated SHR and were partially restored in the treated SHR. Antioxidant therapy had no effect on the measured parameters in the WKY control.

CONCLUSION

Lifelong consumption of antioxidant-rich diet ameliorates HTN and oxidative stress in SHR. This is associated with the reduction of superoxide-generating enzyme, NAD(P)H oxidase, and immunoregulatory factor calcineurin. Antioxidant-rich diet appears to attenuate oxidative stress, not only by fortifying antioxidant defense capacity but also by lowering NAD(P)H oxidase, which is a major source of reactive oxygen species.

Homocysteine and cardiovascular disease in renal disease. Review Article

Elevated homocysteine (hyperhomocysteinaemia) in renal patients is a major concern for physicians. Although cause and effect between homocysteine and cardiovascular disease (CVD) has not been established in either the general population or renal patients, there is much evidence that this relationship does exist. Purported mechanisms that may explain this effect include increases in endothelial injury, smooth muscle cell proliferation, low-density lipoprotein oxidation and changes in haemostatic balance. Renal patients have a much greater incidence of hyperhomocysteinaemia and this may be explained by decreases in either the renal or extrarenal metabolism of the compound. We conclude that data from long-term placebo-controlled trials are urgently required to determine whether hyperhomocysteinaemia in renal patients is a cause of CVD events and requires therapeutic targeting.

Cardiac mitochondrial NADP+-isocitrate dehydrogenase is inactivated through 4-hydroxynonenal adduct formation: an event that precedes hypertrophy development

Mitochondrial NADP+-isocitrate dehydrogenase activity is crucial for cardiomyocyte energy and redox status, but much remains to be learned about its role and regulation. We obtained data in spontaneously hypertensive rat hearts that indicated a partial inactivation of this enzyme before hypertrophy development. We tested the hypothesis that cardiac mitochondrial NADP+-isocitrate dehydrogenase is a target for modification by the lipid peroxidation product 4-hydroxynonenal, an aldehyde that reacts readily with protein sulfhydryl and amino groups. This hypothesis is supported by the following in vitro and in vivo evidence. In isolated rat heart mitochondria, enzyme inactivation occurred within a few minutes upon incubation with 4-hydroxynonenal and was paralleled by 4-hydroxynonenal/NADP+-isocitrate dehydrogenase adduct formation. Enzyme inactivation was prevented by the addition of its substrate isocitrate or a thiol, cysteine or glutathione, suggesting that 4-hydroxynonenal binds to a cysteine residue near the substrate's binding site. Using an immunoprecipitation approach, we demonstrated the formation of 4-hydroxynonenal/NADP+-isocitrate dehydrogenase adducts in the heart and their increased level (210%) in 7-week-old spontaneously hypertensive rats compared with control Wistar Kyoto rats. To the best of our knowledge, this is the first study to demonstrate that mitochondrial NADP+-isocitrate dehydrogenase is a target for inactivation by 4-hydroxynonenal binding. Furthermore, the pathophysiological significance of our finding is supported by in vivo evidence. Taken altogether, our results have implications that extend beyond mitochondrial NADP+-isocitrate dehydrogenase. Indeed, they emphasize the implication of post-translational modifications of mitochondrial metabolic enzymes by 4-hydroxynonenal in the early oxidative stress-related pathophysiological events linked to cardiac hypertrophy development.

Contrasting roles of NADPH oxidase isoforms in pressure-overload versus angiotensin II-induced cardiac hypertrophy

Increased production of reactive oxygen species (ROS) is implicated in the development of left ventricular hypertrophy (LVH). Phagocyte-type NADPH oxidases are major cardiovascular sources of ROS, and recent data indicate a pivotal role of a gp91phox-containing NADPH oxidase in angiotensin II (Ang II)-induced LVH. We investigated the role of this oxidase in pressure-overload LVH. gp91phox-/- mice and matched controls underwent chronic Ang II infusion or aortic constriction. Ang II-induced increases in NADPH oxidase activity, atrial natriuretic factor (ANF) expression, and cardiac mass were inhibited in gp91phox-/- mice, whereas aortic constriction-induced increases in cardiac mass and ANF expression were not inhibited. However, aortic constriction increased cardiac NADPH oxidase activity in both gp91phox-/- and wild-type mice. Myocardial expression of an alternative gp91phox isoform, Nox4, was upregulated after aortic constriction in gp91phox-/- mice. The antioxidant, N-acetyl-cysteine, inhibited pressure-overload-induced LVH in both gp91phox-/- and wild-type mice. These data suggest a differential response of the cardiac Nox isoforms, gp91phox and Nox4, to Ang II versus pressure overload.

Differential relaxing responses to particulate or soluble guanylyl cyclase activation on endothelial cells: a mechanism dependent on PKG-I alpha activation by NO/cGMP

cGMP is generated in endothelial cells after stimulation of soluble guanylyl cyclase (sGC) by nitric oxide (NO) or of particulate guanylyl cyclase (pGC) by natriuretic peptides (NP). We examined whether localized increases in cytosolic cGMP have distinct regulatory roles on the contraction induced by H2O2 treatment in human umbilical vein endothelial cells. cGMP concentrations and temporal dynamics were different upon NO stimulation of sGC or C-type NP (CNP) activation of pGC and did not correlate with their relaxing effects measured as planar cell surface area after H2O2 challenge. cGMP production due to sGC stimulation was always smaller and more brief than that induced by pGC stimulation with CNP, which was greater and remained elevated longer. The NO effects on cell relaxation were cGMP dependent because they were blocked by sGC inhibition with 1H-(1,2,4)Oxadiazolo(4,3-a)quinoxaline-1-one and mimicked by 8-Br-cGMP. An antagonist of the cGMP-dependent protein kinase type-I (PKG-I) also inhibited the NO-induced effects. The cell contraction induced by H2O2 produces myosin light chain (MLC) phosphorylation and NO prevented it completely, whereas CNP only produced a partial inhibition. Transfection with a dominant negative form of PKG type-I alpha completely reversed the NO-induced effects on MLC phosphorylation, whereas it only partially inhibited the effects due to CNP. Taken together, these results demonstrate that the NO/sGC/cGMP pathway induces endothelial cell relaxation in a more efficient manner than does CNP/pGC/cGMP pathway, an effect that might be related to a selective stimulation of PKG-1 alpha by NO-derived cGMP. Consequently, stimulated PKG-I alpha may phosphorylate important protein targets that are necessary to inhibit the endothelial contractile machinery activated by oxidative stress.

Hydrogen peroxide increases the activity of rat sympathetic preganglionic neurons in vivo and in vitro

Reactive oxygen species (ROS) have been shown to modulate neuronal synaptic transmission and have also been implicated in cardiovascular diseases such as hypertension. The hypothesis that H(2)O(2) acting on sympathetic preganglionic neurons (SPNs) affects spinal sympathetic outflow was tested in the present study. H(2)O(2) was applied intrathecally via an implanted cannula to the T7-T9 segments of urethane-anesthetized rats. Blood pressure and heart rate were used as indices to evaluate the spinal sympathetic effects of H(2)O(2) in vivo. Intrathecal H(2)O(2) (100-1000 nmol) dose-dependently increased both the mean arterial pressure and heart rate. Reproducible pressor effects of H(2)O(2) (1000 nmol) applied consecutively at intervals of 30 min were observed. The pressor effects of intrathecal H(2)O(2) (1000 nmol) were attenuated by pretreatment with intrathecal administration of catalase (500 units), or N-acetyl-cysteine (1000 nmol). The pressor effects of intrathecal H(2)O(2) (1000 nmol) were also antagonized dose-dependently by prior intrathecal injection of AP-5 (DL-2-amino-5- phosphonovaleric acid, 10 and 30 nmol), or 6-cyano-7- nitroquinoxaline-2,3-dione, 10 and 30 nmol. In vitro electrophysiological study in spinal cord slices showed that superfusion of 1 mM H(2)O(2) for 3 min, which had no effect on membrane potential, caused an increase in amplitude of excitatory postsynaptic potentials in SPNs, but had little effect on that of inhibitory postsynaptic potentials. Taken together, these results demonstrated that oxidative stress in spinal cord may cause an increase in spinal sympathetic tone by acting on SPNs, which may contribute to ROS-induced cardiovascular dysfunction.

Effect of Vitamin C Supplementation on Oxidative DNA Damage in an Experimental Model of Lead-Induced Hypertension

AIMS

Chronic exposure to lead results in sustained hypertension in humans and experimental animals. We investigated the possible role of reactive oxygen species (ROS) and their impact on DNA damage in lead-induced hypertension. Further the effect of short-term supplementation of vitamin C is also demonstrated.

METHODS

Male Wistar rats were treated with either lead acetate (100 ppm) alone or lead acetate plus vitamin C (20 mg/rat/day). The control rats were fed regular rat chow. Blood pressure, antioxidants, total antioxidant status as measured by ferric-reducing antioxidant power, nitric oxide (NO) metabolites, malondialdehyde (MDA) and 8-hydroxy 2-deoxyguanosine were determined after 0, 1, 2 and 3 months.

RESULTS

The lead-exposed group showed a significant rise in blood pressure, lipid peroxidation (MDA) and a substantial oxidative damage to the DNA. A significant fall in NO metabolites, total antioxidant levels and ferric-reducing antioxidant power was also observed in this group. Concomitant administration of vitamin C ameliorated hypertension, normalized NO levels and abrogated lipid peroxidation. Also, it completely prevented oxidative damage to the DNA.

CONCLUSIONS

These findings point to enhanced ROS-mediated inactivation and sequestration of NO which can potentially contribute to hypertension, lipid peroxidation, reduced antioxidant status and oxidative DNA damage. The beneficial effects of vitamin C on these parameters support the role of increased ROS activity in the pathogenesis of these abnormalities in this model.

Oxygen free radical release in human failing myocardium is associated with increased activity of rac1-GTPase and represents a target for statin treatment

BACKGROUND

Reactive oxygen species (ROS) contribute to the development of heart failure. A potential source of myocardial ROS is the NADPH oxidase, which is regulated by the small GTP-binding protein rac1. Isoprenylation of rac1 can be inhibited by statin therapy. Thus, we examined ROS and rac1 in human failing myocardium and tested their regulation by statins in vivo.

METHODS AND RESULTS

In human left ventricular myocardium from patients with ischemic cardiomyopathy (ICM) or dilated cardiomyopathy (DCM), NADPH oxidase activity was increased 1.5-fold compared with nonfailing controls (P<0.05, n=8). In failing myocardium, increased oxidative stress determined by measurements of lipid peroxidation and aconitase activity was associated with increased translocation of rac1 from the cytosol to the membrane. Pull-down assays revealed a 3-fold increase of rac1-GTPase activity in ICM and DCM. In parallel, membrane expression of the NADPH oxidase subunit p47phox, but not p67phox, was upregulated in failing compared with nonfailing myocardium. In right atrial myocardium from patients undergoing cardiac surgery who were prospectively treated with atorvastatin or pravastatin (40 mg/d, 4 weeks), rac1-GTPase activity was decreased to 67.9+/-12% and 65.6+/-13.8% compared with patients without statin (P<0.05, n=8). Both atorvastatin and pravastatin significantly reduced angiotensin II-stimulated but not basal NADPH oxidase activity.

CONCLUSIONS

Failing myocardium of patients with DCM and ICM is characterized by upregulation of NADPH oxidase-mediated ROS release associated with increased rac1 activity. Oral statin treatment inhibits myocardial rac1-GTPase activity. These data suggest that extrahepatic effects of statins can be observed in humans and may be beneficial for patients with chronic heart failure.

Preconditioning attenuates ischemia-reperfusion-induced remodeling of Na+-K+-ATPase in hearts

The aim of this study was to determine whether changes in protein content and/or gene expression of Na+-K+-ATPase subunits underlie its decreased enzyme activity during ischemia and reperfusion. We measured protein and mRNA subunit levels in isolated rat hearts subjected to 30 min of ischemia and 30 min of reperfusion (I/R). The effect of ischemic preconditioning (IP), induced by three cycles of ischemia and reperfusion (10 min each), was also assessed on the molecular changes in Na+-K+-ATPase subunit composition due to I/R. I/R reduced the protein levels of the alpha2-, alpha3-, beta1-, and beta2-isoforms by 71%, 85%, 27%, and 65%, respectively, whereas the alpha1-isoform was decreased by <15%. A similar reduction in mRNA levels also occurred for the isoforms of Na+-K+-ATPase. IP attenuated the reduction in protein levels of Na+-K+-ATPase alpha2-, alpha3-, and beta2-isoforms induced by I/R, without affecting the alpha1- and beta1-isoforms. Furthermore, IP prevented the reduction in mRNA levels of Na+-K+-ATPase alpha2-, alpha3-, and beta1-isoforms following I/R. Similar alterations in protein contents and mRNA levels for the Na+/Ca2+ exchanger were seen due to I/R as well as IP. These findings indicate that remodeling of Na+-K+-ATPase may occur because of I/R injury, and this may partly explain the reduction in enzyme activity in ischemic heart disease. Furthermore, IP may produce beneficial effects by attenuating the remodeling of Na+-K+-ATPase and changes in Na+/Ca2+ exchanger in hearts after I/R.

Aorta of ApoE-deficient mice responds to atherogenic stimuli by a prelesional increase and subsequent decrease in the expression of antioxidant enzymes

Oxidative stress has been implicated in the development of atherosclerotic lesions. We evaluated the relationship between extent of atherosclerotic lesion formation and vascular expression of pro- and antioxidant enzymes in apoE-deficient mice. On normal chow, these mice showed elevated serum cholesterol levels (7.5- to 9.5-fold), and age-dependent, spontaneous development of all stages of atherosclerotic lesions, starting at the age of 12 weeks. RNA was extracted from the aortic arch and descending aorta, and mRNA expression of pro- and antioxidant enzymes was measured with real-time PCR. Local infiltration of monocytes/macrophages, reflected by increased vascular expression of CD68 mRNA (>10-fold), indicated that the arch was more susceptible than the descending aorta. The expression of catalase-1 and various isoforms of superoxide dismutase, glutathione peroxidase, and glutathione S-transferase alpha was significantly increased in the aortic arch, but not in the descending aorta, in the period preceding lesion formation (age 6 to 12 weeks). These expression levels were 1.5 to 5 times higher than in age-matched wild-type animals. Remarkably, there was an inverse relationship between extent of lesion formation and the mRNA levels of antioxidant enzymes, most of which started to decline after 12 weeks, as lesions developed. In contrast, inducible nitric oxide synthase expression increased 4-fold in the aortic arch over the course of the disease. Our results suggest that the arterial wall responds to increased serum levels of atherogenic lipoproteins by stimulating expression of antioxidant enzymes. The observed co-ordinate decline in expression of many of these protective systems may greatly accelerate the development of atherosclerosis.