Oxygen free radicals and congestive heart failure

Functional alterations in NO, PGI2and EDHF pathways in the aortic endothelium after myocardial infarction in rats

BACKGROUND

Previous work on endothelial dysfunction in post-MI heart failure has shown conflicting results.

AIM

To analyze gender related alterations in NO-, PGI(2)- and EDHF-dependent endothelial function in the thoracic aorta 7 and 42 days after myocardial infarction (MI).

METHODS AND RESULTS

MI was induced by coronary artery ligation in female and male Sprague-Dawley rats. There was no gender related difference in infarct-size or in the impairment of fractional shortening of the left ventricle 42 days after coronary ligation. Neither acetylcholine-induced (Ach) vasodilation nor basal PGI(2) production in the aorta was modified by coronary ligation. Interestingly, 7 days after MI, basal NO production was impaired and the EDHF component of Ach-induced vasodilation was up-regulated, in both male and female rats. However, 42 days post-MI, basal NO was only impaired in male rats, while EDHF was only up-regulated in female rats.

CONCLUSION

MI induced impairment of functional activity of basal NO production and adaptive up-regulation of the EDHF component of Ach-induced relaxation. The above alterations in endothelial function in the aorta were gender-specific at 42 days but not 7 days after MI. Some of the previously reported discrepancies in the development of endothelial dysfunction in the post-MI period may be gender related differences.

Micronutrients and their supplementation in chronic cardiac failure. An update beyond theoretical perspectives

Physicians' use of micronutrients to improve symptoms or outcomes in chronic illness has until recently been guided by limited data on the actions of individual agents in vitro or in animal studies. However several recently published clinical trials have provided information about which groups of patients are likely to benefit from which combination of micronutrients. Patients with chronic cardiac failure (CCF), particularly elderly individuals, have several reasons to be deficient in micronutrients including reduced intake, impaired gastrointestinal absorption and increased losses on the background of increased utilisation due for example to increased oxidative stress. Studies of nutritional supplementation in CCF patients have usually concentrated on specific agents. However given that many micronutrients have synergistic influences upon metabolic processes this strategy might merely lead to a shifting of a limiting step. Rather, a strategy of increasing the availability of multiple agents at once might be more logical. The aim of this article is to briefly review the experimental rationale for each of the micronutrients of potential benefit in chronic heart failure and examine the current clinical trial evidence supporting their use.

Oxidant stress and antioxidant status among patients with nonalcoholic fatty liver disease (NAFLD)

BACKGROUND

One of the major pathogenic mechanisms for progression of nonalcoholic fatty liver disease (NAFLD) is oxidative stress. Recently, many studies have demonstrated the role of oxidative stress in NAFLD however, studies describing the antioxidant status in these patients are lacking.

AIM

To study the levels of oxidative stress and antioxidant status among patients with NAFLD.

PATIENTS AND METHODS

It was a prospective study in which 29 patients with NAFLD, 25 diseased controls with chronic viral hepatitis, and 23 healthy controls were enrolled. Apart from standard biochemical parameters, lipid peroxidation products were measured as thiobarbituric acid reactive substances. As measures of antioxidant capacity, superoxide dismutase, vitamin C levels and ferric reducing ability of plasma were measured.

RESULTS

Level of thiobarbituric acid reactive substances was significantly higher among NAFLD patients as compared with diseased [4.7 nmol/mL (1.0 to 10.2) vs. 2.4 nmol/mL (0.8 to 10.7); P=0.02] or healthy controls [4.7 nmol/mL (1.0 to 10.2) vs. 1.8 nmol/mL (0.5 to 4.1); P=0.0001]. FRAP was found to be significantly higher in patients with NAFLD as compared with healthy controls [450.3 (197.6 to 733.3) vs. 340.8 (141.6 to 697.5) mumol Fe liberated; P=0.04], even though it was similar between NAFLD and diseased controls. Among NAFLD patients, there was no significant correlation between histological grading or staging and levels of pro and antioxidants.

CONCLUSIONS

Products of lipid peroxidation are significantly increased among patients with NAFLD as compared with chronic viral hepatitis or healthy controls. Larger studies and newer markers of oxidative stress are required to clarify the association between oxidative stress and histological severity in NAFLD.

The effects of propofol on neutrophil function, lipid peroxidation and inflammatory response during elective coronary artery bypass grafting in patients with impaired ventricular function

BACKGROUND

Coronary artery bypass grafting (CABG) with cardiopulmonary bypass elicits a potent reperfusion injury and inflammatory response, more intense in patients with impaired myocardial function. Propofol has antioxidant properties which may attenuate such a response.

METHODS

In total, 27 patients with impaired left ventricular function undergoing CABG were randomly allocated to receive either target-controlled infusion propofol (P) or saline (S) immediately before aortic cross-clamp release until 4 h after reperfusion. Troponin-I, Urinary 8-epi PGF-2alpha isoprostane, coronary sinus and systemic malondialdehyde concentrations, Interleukin-6 (IL-6), -8 and -10 concentrations and leucocytes function studies (neutrophil respiratory burst, phagocytosis, CD-11b and CD-18 expression) were measured.

RESULTS

Propofol decreased MDA coronary sinus concentration at 1, 3 and 5 min after reperfusion (P<0.01); 60 min after reperfusion a significant difference between the two groups in systemic MDA concentrations was also seen. IL-6 concentration increases were significantly greater in Group S than Group P, 4 h after reperfusion [1118 (1333) pg ml(-1) vs 228 (105) pg ml(-1), P<0.01]. Serum IL-8 concentrations did not increase significantly in either group. Compared with baseline values IL-10 concentrations decreased after reperfusion but the values were higher in the propofol group than in the control group [22 (16) vs 11 (4) pg ml(-1), P<0.05]. No difference in leucocyte function or urinary isoprostane concentrations was demonstrated.

CONCLUSION

Propofol attenuates free-radical-mediated lipid peroxidation and systemic inflammation in patients with impaired myocardial function undergoing CABG.

Elevated levels of oxidative DNA damage in serum and myocardium of patients with heart failure

BACKGROUND

Oxidative stress has been implicated in the pathogenesis of chronic heart failure. The present study investigated whether the levels of 8-hydroxy-2-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, were elevated in the serum and myocardium of patients with dilated cardiomyopathy (DCM), and furthermore whether carvedilol, a vasodilating beta-blocker with antioxidant activity, could reduce the levels.

METHODS AND RESULTS

Serum levels of 8-OHdG were measured by enzyme immunoassay in 56 patients with DCM and in 20 control subjects. DCM patients had significantly elevated serum levels of 8-OHdG compared with control subjects. Endomyocardial biopsy samples obtained from 12 DCM patients and 5 control subjects with normal cardiac function were studied immunohistochemically for the expression of 8-OHdG. Positive 8-OHdG staining was found in the nuclei of cardiomyocytes from DCM patients but not in those from control subjects. After treatment with carvedilol, the serum levels of 8-OHdG in DCM patients significantly decreased by 19%, together with amelioration of heart failure.

CONCLUSIONS

Levels of 8-OHdG are elevated in the serum and myocardium of patients with heart failure. Treatment with carvedilol might be effective for decreasing the oxidative DNA damage.

Mitochondrial oxidative stress, DNA damage, and heart failure

Recent experimental and clinical studies have suggested that oxidative stress is enhanced in heart failure. The production of oxygen radicals is increased in the failing heart, whereas antioxidant enzyme activities are preserved as normal. Mitochondrial electron transport is an enzymatic source of oxygen radical generation and also a target of oxidant-induced damage. Chronic increases in oxygen radical production in the mitochondria can lead to a catastrophic cycle of mitochondrial DNA (mtDNA) damage as well as functional decline, further oxygen radical generation, and cellular injury. Reactive oxygen species induce myocyte hypertrophy, apoptosis, and interstitial fibrosis by activating matrix metalloproteinases. These cellular events play an important role in the development and progression of maladaptive cardiac remodeling and failure. Therefore, mitochondrial oxidative stress and mtDNA damage are good therapeutic targets. Overexpression of mitochondrial transcription factor A (TFAM) could ameliorate the decline in mtDNA copy number and preserve it at a normal level in failing hearts. Consistent with alterations in mtDNA, the decrease in oxidative capacities was also prevented. Therefore, the activation of TFAM expression could ameliorate the pathophysiologic processes seen in myocardial failure. Inhibition of mitochondrial oxidative stress and mtDNA damage could be novel and potentially very effective treatment strategies for heart failure.

Isosorbide dinitrate and hydralazine hydrochloride: a review of efficacy and safety

In the USA alone, there are over 5,000,000 people diagnosed with heart failure. A disproportionate number of African-Americans are affected by this disease, with increased morbidity and mortality, yet they are tremendously under-represented in clinical trials. Several drugs have been approved for use in heart failure based on clinical trials, with percentages of African-American subjects as low as 1%. In the African-American Heart Failure Trial the use of BiDil, a drug combining isosorbide dinitrate and hydralazine hydrochloride, demonstrated a 43% decrease in overall mortality and a 39% decrease in first hospitalization. The combination consists of 20 mg of isosorbide and 37.5 mg hydralazine hydrochloride in a fixed dose that functions as a nitric oxide enhancer and an antioxidant, and helps to prevent tolerance to the prolonged use of nitrate. The hemodynamic effects of the combination drug in heart failure includes increased cardiac output. The US Food and Drug Administration approved the combination of isosorbide dinitrate based on the African-American Heart Failure Trial. Further clinical trials utilizing isosorbide dinitrate will hopefully determine the benefit of this combination in a larger population, including caucasians and other racial/ethnic groups.

Oxidative stress in chronic cardiopathy associated with Chagas disease

BACKGROUND

Chagas disease is characterized by chronic inflammation similar to autoimmune diseases. The imbalance between prooxidant and antioxidant defenses is known as oxidative stress, and is often associated with inflammatory processes of many diseases.

METHODS

The present work measured some components of the antioxidant system present in the blood of four groups of patients in different stages of chronic Chagas heart disease (n=10 each group), according to the modified Los Andes clinical-hemodynamic classification. Each group of chagasic patients was compared with four groups of healthy subjects, and chagasic group IV was compared to group V, characterized by rheumatic cardiac disease, giving a total of 90 subjects. Antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), and the contents of reduced (GSH), oxidized (GSSG) and total glutathione (TG) were assayed.

RESULTS

SOD, CAT and GR activities showed essentially no differences among the four groups, however, intraerythrocytic GSH concentrations showed decreased values parallel to the progression of the disease. In addition, the glutathione peroxidase (GPx) activities were higher in groups III and V and lower in groups I, II and IV, also suggesting an antioxidant depletion with progression of the disease. In contrast, except for SOD and CAT activities, patients from group V showed a generally higher antioxidant capacity compared to the chagasic group IV.

CONCLUSION

The results indicate a general increase of oxidative stress parallel to the progression of Chagas disease.

Contribution of reactive oxygen species to the pathogenesis of left ventricular failure in Dahl salt-sensitive hypertensive rats: effects of angiotensin II blockade

OBJECTIVE

We investigated the contribution of reduced nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase-dependent reactive oxygen species (ROS) generation to the pathogenesis of diastolic heart failure (DHF) in Dahl salt-sensitive (DS) hypertensive rats, with the aim of testing our hypothesis that the cardioprotective effects of angiotensin II (Ang II) blockade are provided by the suppression of this pathway.

METHODS

DS rats were maintained on high (H: 8.0% NaCl) or low (L: 0.3% NaCl) salt diets from age 7 to 17 weeks. DS/H rats were also treated with candesartan cilexetil (10 mg/kg per day, orally) or a superoxide dismutase mimetic, tempol (3 mmol/l in drinking water) from age 7 to 17 weeks.

RESULTS

DS/H rats represented hypertension, left ventricular (LV) relaxation abnormality and myocardial stiffening with preserved systolic heart function. As compared with DS/L rats, DS/H rats showed higher levels of transforming growth factor-beta (TGF-beta), connective tissue growth factor (CTGF), p22phox and gp91phox mRNA expression, NADPH oxidase activity and thiobarbituric acid-reactive substance (TBARS) contents in LV tissues. Gene expression of uncoupling protein-2 (UCP-2), an inner mitochondrial membrane proton transporter, was also 2.8 +/- 0.5-fold higher. In DS/H rats, treatment with candesartan did not alter blood pressure, but resulted in a marked improvement of the hemodynamic deterioration; these therapeutic effects were accompanied by decreases in myocardial NADPH oxidase activity, TBARS contents and the expression of TGF-beta, CTGF, p22phox, gp91phox and UCP-2. Similar therapeutic effects were provided by treatment with tempol in DS/H rats.

CONCLUSIONS

Our data suggest that NADPH oxidase-mediated ROS production contributes to the pathogenesis of DHF in DS hypertensive rats, and that the cardioprotective effects of AngII blockade are, at least partially, mediated through the suppression of this pathway.

Myocardial Antioxidant Status in Chronic Alcoholism

BACKGROUND

Excessive ethanol intake is one of the most frequent causes of acquired dilated cardiomyopathy in developed countries. The pathogenesis is multifactorial, with the antioxidant imbalance of cardiac muscle being a potential factor. The current study evaluates myocardial antioxidant status in ethanol consumers and its relation to cardiac damage.

METHODS

The authors assessed superoxide dismutase, glutathione peroxidase, and glutathione reductase enzyme activities as well as the total antioxidant status capacity in myocardial samples obtained from organ donors with sudden death of traumatic or neurological origin. They studied 23 high-dose chronic alcohol consumers, 27 individuals with long-standing hypertension, and 11 healthy controls. Cardiomyopathy was defined according to standard functional and histological criteria.

RESULTS

Patients with dilated cardiomyopathy, either of alcoholic or hypertensive origin, showed increased myocardial superoxide dismutase activities compared with patients without cardiomyopathy (p < 0.001, both) and controls (p < 0.05, both). Total antioxidant status capacity and the activity of glutathione peroxidase and glutathione reductase enzymes were similar in all groups. Superoxide dismutase activity was related to the presence of cardiac enlargement and the degree of cardiac histological damage. The amount and type of alcoholic beverages as well as the nutritional status of the patients were not related to myocardial antioxidant activity.

CONCLUSIONS

The presence of dilated cardiomyopathy, of either alcoholic or hypertensive origin, is related to an increase in myocardial superoxide dismutase activity.

Mitochondrial oxidative stress and heart failure

Recent experimental and clinical studies have suggested that oxidative stress is enhanced in heart failure. Chronic increases in oxygen radical production in the mitochondria can lead to a catastrophic cycle of mitochondrial DNA (mtDNA) damage as well as functional decline, further oxygen radical generation, and cellular injury. Reactive oxygen species induce myocyte hypertrophy, apoptosis, and interstitial fibrosis by activating matrix metalloproteinases. These cellular events play an important role in the development and progression of maladaptive cardiac remodeling and failure. Overexpression of mitochondrial transcription factor A (TFAM) could ameliorate the decline in mtDNA copy number and preserve it at a normal level in failing hearts. Consistent with alterations in mtDNA, the decrease in oxidative capacities was also prevented. Therefore, the activation of TFAM expression could ameliorate the pathophysiological processes seen in myocardial failure. Inhibition of mitochondrial oxidative stress and DNA damage could be the most effective and novel treatment strategies for heart failure.

Increased Gene Expression of Glutathione Peroxidase-3 in Diabetic Mouse Heart

Increased incidence of heart disease is reported in patients with diabetes. To elucidate a molecular profile of expressed genes during the progression of diabetes, a cDNA array was screened in the hearts of mice treated with streptozotocin (200 mg/kg, i.v.). Among the genes investigated, the plasma type glutathione peroxidase, GPX-3, was predominantly up-regulated in diabetic mice compared with control mice. In northern blot analysis, a significant increase in GPX-3 expression was observed as early as 5 d after the induction of hyperglycemia. On day 21, a nearly three-fold induction was demonstrated. Daily administration of insulin (0.2 U/d, s.c.) for 21 d almost completely abolished the increase in GPX-3 mRNA in streptozotocin-treated mice, suggesting that the expression level of the GPX-3 gene was dependent on insulin and serum glucose. Increased GPX-3 may play a significant role in protecting cardiomyocytes from oxidative stress caused by hyperglycemia.

Reduced oxidative stress in parallel to improved cardiac performance one year after selective removal of anti-beta 1-adrenoreceptor autoantibodies in patients with idiopathic dilated cardiomyopathy: data of a preliminary study

Patients with idiopathic dilated cardiomyopathy (IDC) were treated with selective immunoadsorption to remove anti-beta 1-adrenoreceptor autoantibodies (anti-beta1A-AB). After one year, the effect on cardiac performance and oxidative stress was tested. Extracorporeal immunoadsorption of the whole IgG class in IDC patients for the removal of anti-beta1A-AB reduced oxidative stress in parallel to an improvement of cardiac performance. However, the non-specificity of IgG adsorption means that these beneficial effects cannot be attributed exclusively to anti-beta1A-AB removal. In an open clinical pilot study enrolling 8 patients with IDC prior to and one year after selective immunoadsorption of anti-beta1A-AB, plasma markers for oxidative stress--thiobarbituric acid-reactive substances (TBARS), lipid peroxides (LPO) and anti-oxidized low-density lipoprotein autoantibodies (anti-oxLDL-AB)--were measured in parallel to evaluation of the left ventricular function using conventional echocardiography and wall motion analysis by tissue Doppler imaging. After one year, TBARS (Wilcoxon test with bootstrapping simulation for paired data: 95% confidence interval of the P value 0.020 to 0.029) and anti-oxLDL-AB (P = 0.025 to 0.035) were decreased in parallel to an improvement of the peak systolic wall motion velocity (P = 0.006 to 0.01) and left ventricular ejection fraction (P = 0.002 to 0.02). For changes over the study period, a direct correlation with borderline significance (P = 0.076) was calculated for TBARS to the left ventricular diameter in the diastole. One year after selective immunoadsorption for anti-beta1A-AB removal, patients with ICD show a reduction in oxidative stress and a parallel improvement in cardiac performance.

Correction of Defective Interdomain Interaction Within Ryanodine Receptor by Antioxidant Is a New Therapeutic Strategy Against Heart Failure

Background— Defective interdomain interaction within the ryanodine receptor (RyR2) seems to play a key role in the pathogenesis of heart failure, as shown in recent studies. In the present study we investigated the effect of oxidative stress on the interdomain interaction, its outcome in the cardiac function in heart failure, and the possibility of preventing the problem with antioxidants.

Methods and Results— Sarcoplasmic reticulum (SR) vesicles were isolated from dog left ventricular (LV) muscle (normal or rapid ventricular pacing for 4 weeks with or without the antioxidant edaravone). In the edaravone-treated paced dogs (EV+), but not in the untreated paced dogs (EV−), normal cardiac function was restored almost completely. In the SR vesicles isolated from the EV−, oxidative stress of the RyR2 (reduction in the number of free thiols) was severe, but it was negligible in EV+. The oxidative stress of the RyR2 destabilized interdomain interactions within the RyR2 (EV−), but its effect was reversed in EV+. Abnormal Ca 2+ leak through the RyR2 was found in EV− but not in EV+. The amount of the RyR2-bound FKBP12.6 was less in EV− than in normal dogs, whereas it was restored almost to a normal amount in EV+. The NO donor 3-morpholinosydnonimine (SIN-1) reproduced, in normal SR, several abnormal features seen in failing SR, such as defective interdomain interaction and abnormal Ca 2+ leak. Both cell shortening and Ca 2+ transients were impaired by SIN-1 in isolated normal myocytes, mimicking the pathophysiological conditions in failing myocytes. Incubation of failing myocytes with edaravone restored the normal properties.

Conclusions— During the development of heart failure, edaravone ameliorated the defective interdomain interaction of the RyR2. This prevented Ca 2+ leak and LV remodeling, leading to an improvement of cardiac function and an attenuation of LV remodeling.

MCI-186 (edaravone), a novel free radical scavenger, protects against acute autoimmune myocarditis in rats

In this study, we tested the hypothesis that MCI-186 (3-methyl-1-phenyl-2-pyrazolin-5-one; edaravone), a novel free radical scavenger, protects against acute experimental autoimmune myocarditis (EAM) in rats by the radical scavenging action associated with the suppression of cytotoxic myocardial injury. Recent evidence suggests that oxidative stress may play a role in myocarditis. We administered MCI-186 intraperitoneally at 1, 3, and 10 mg·kg−1·day−1 to rats with EAM for 3 wk. The results were compared with untreated rats with EAM. MCI-186 treatment did not affect hemodynamics. MCI-186 treatment (3 and 10 mg·kg−1·day−1) reduced the severity of myocarditis as assessed by comparing the heart-to-body weight ratio and pathological scores. Myocardial interleukin-1β (IL-1β)-positive cells and myocardial oxidative stress overload with DNA damage in rats with EAM given MCI-186 treatment were significantly less compared with those of the untreated rats with EAM. In addition, MCI-186 treatment decreased not only the myocardial protein carbonyl contents but also the myocardial thiobarbituric acid reactive substance products in rats with EAM. The formation of hydroxyl radicals in MCI-186-treated heart homogenates was decreased compared with untreated heart homogenates. Furthermore, cytotoxic activities of lymphocytes of rats with EAM treated with MCI-186 were significantly lower compared with those of the untreated rats with EAM. Hydroxyl radicals may be involved in the development of myocarditis. MCI-186 protects against acute EAM in rats associated with scavenging hydroxyl free radicals, resulting in the suppression of autoimmune-mediated myocardial damage associated with reduced oxidative stress state.

Lipid peroxidation is not increased in heart failure patients on modern pharmacological therapy

BACKGROUND

Previous studies support a role of oxygen-free radicals in the development of congestive heart failure (CHF). The aim of this study was to investigate whether lipid peroxidation is increased in CHF patients on modern pharmacological therapy and whether there is a positive correlation between plasma levels of markers of lipid peroxidation and severity of heart failure (HF). Plasma malondialdehyde (MDA) and isoprostanes are often used as markers of lipid peroxidation and oxidative stress. We also studied whether long-term treatment with isosorbide-5-mononitrate (IS-5-MN) in combination with standard HF therapy affects P-MDA levels in patients with evidence of left ventricular (LV) dysfunction following acute myocardial infarction (AMI).

MATERIALS AND METHODS

Ninety-two patients with clinical or echocardiographic evidence of LV-dysfunction following AMI were randomized to treatment with either IS-5-MN or placebo. In a subgroup of 83 patients with available plasma MDA, echocardiography, right-heart catherization, and plasma natriuretic peptides were evaluated. Control subjects were 80 healthy blood donors. A second study group consisted of 56 patients with CHF, evaluated with respect to LV function, brain natriuretic peptide and markers of oxidative stress (P-MDA and 8-isoprostane). The second control group comprised 50 healthy subjects.

RESULTS

Lipid peroxidation measured by P-MDA and 8-isoprostane was not increased in patients with LV dysfunction treated with standard HF therapy. No positive correlation was found to the severity of HF. Long-term IS-5-MN therapy did not influence P-MDA concentrations.

CONCLUSIONS

Although results from many experimental and clinical studies suggest that oxidative stress is increased in HF, this may not be true for patients treated with beta blockers and inhibitors of the renin-angiotensin system.

The African American Heart Failure Trial: a clinical trial update

Progressive vascular and myocardial remodeling in heart failure is effectively slowed by therapy with neurohormonal antagonists, including angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, aldosterone antagonists, and adrenergic-receptor blockers. These therapies, along with the correction of hemodynamic abnormalities, have dramatically reduced morbidity and mortality in patients with heart failure. Endothelial dysfunction, increased oxidative stress, and decreased bioavailability of nitric oxide (NO) also occur in heart failure. Data suggest that endothelial dysfunction and reduced NO bioavailability may be more prevalent in populations who self-identify as African Americans. Thus, differences observed in the African American population with respect to prevalence of heart failure, etiology, outcomes, and response to medication may in part be explained by differences in the relative contributions of neurohormonal activation and diminished NO bioavailability to the progression of heart failure. The African American Heart Failure Trial (A-HeFT) was designed to assess the benefit of fixed-dose combination isosorbide dinitrate-hydralazine (ISDN-HYD) in an African American population with advanced heart failure. The A-HeFT enrolled 1,050 African American patients with New York Heart Association (NYHA) class III-IV heart failure with dilated ventricles and low ejection fractions. Patients were randomized to receive either a fixed-dose combination of ISDN-HYD or placebo added to standard neurohormonal blockade. The primary end point was a composite score in which mortality, hospitalization, and quality of life were weighted. On July 19, 2004, the independent Data Safety Monitoring Committee recommended early termination of the trial because of a significant mortality benefit in the cohort receiving fixed-dose ISDN-HYD. The A-HeFT confirms the benefit of fixed-dose ISDN-HYD, which may enhance NO bioavailability in African American patients with NYHA class III-IV heart failure and suggests that NO-enhancing therapy is an effective new treatment strategy for heart failure. In addition, the A-HeFT affirms the critical importance of the inclusion of population subgroups in clinical trials both as a way to probe for pathophysiologic mechanisms of disease and to devise optimal treatment strategies. The rich and unique A-HeFT database will provide new opportunities to understand the pathophysiology and management of heart failure.

Muscle wasting in cardiac cachexia

Cardiac cachexia is a serious complication of chronic heart failure which is characterized by complex changes that overall lead to a catabolic/anabolic imbalance resulting in body wasting and a poor prognosis. The wasting process affects all body components, but particularly the skeletal musculature, causing extreme fatigue and weakness, especially in cachectic heart failure patients. Available evidence suggests that several pathophysiologic pathways play a role in the muscle wasting process. Metabolic, neurohormonal, and immune abnormalities lead to an altered regulation of proliferation, differentiation, apoptosis, and metabolism in skeletal muscle, finally resulting in deterioration of the underlying cause with symptomatic exercise intolerance. Possible treatment strategies against muscle wasting and cachexia in chronic heart failure are also described here. As there is no validated therapy for cardiac cachexia yet, further research is necessary to find more therapeutic options for the wasting process.

Diaphragmatic free radical generation increases in an animal model of heart failure

Heart failure evokes diaphragm weakness, but the mechanism(s) by which this occurs are not known. We postulated that heart failure increases diaphragm free radical generation and that free radicals trigger diaphragm dysfunction in this condition. The purpose of the present study was to test this hypothesis. Experiments were performed using halothane-anesthetized sham-operated control rats and rats in which myocardial infarction was induced by ligation of the left anterior descending coronary artery. Animals were killed 6 wk after surgery, the diaphragms were removed, and the following were assessed: 1) mitochondrial hydrogen peroxide (H2O2) generation, 2) free radical generation in resting and contracting intact diaphragm using a fluorescent-indicator technique, 3) 8-isoprostane and protein carbonyls (indexes of free radical-induced lipid and protein oxidation), and 4) the diaphragm force-frequency relationship. In additional experiments, a group of coronary ligation animals were treated with polyethylene glycol-superoxide dismutase (PEG-SOD, 2,000 units·kg−1·day−1) for 4 wk. We found that coronary ligation evoked an increase in free radical formation by the intact diaphragm, increased diaphragm mitochondrial H2O2 generation, increased diaphragm protein carbonyl levels, and increased diaphragm 8-isoprostane levels compared with controls ( P < 0.001 for the first 3 comparisons, P < 0.05 for 8-isoprostane levels). Force generated in response to 20-Hz stimulation was reduced by coronary ligation ( P < 0.05); PEG-SOD administration restored force to control levels ( P < 0.03). These findings indicate that cardiac dysfunction due to coronary ligation increases diaphragm free radical generation and that free radicals evoke reductions in diaphragm force generation.

Does contrast echocardiography induce increases in markers of myocardial necrosis, inflammation and oxidative stress suggesting myocardial injury?

Background

Contrast echocardiography is a precise tool for the non-invasive assessment of myocardial function and perfusion. Side effects of contrast echocardiography resulting from contrast-agent induced myocardial micro-lesions have been found in animals. The goal of this study is to measure markers of myocardial necrosis, inflammation and oxidative stress in humans to evaluate potential side-effects of contrast echocardiography.

Methods

20 patients who underwent contrast echocardiography with Optison as the contrast medium were investigated. To evaluate myocardial micro-necrosis, inflammation and oxidative stress, cardiac troponin I (cTnI), tumor necrosis factor-α (TNF-α), interleukin (IL)-6, -8 and thiobarbituric acid reactive substances (TBARS) were measured at baseline and at 2, 4, 8 and 24 hours after contrast echocardiography.

Results

At baseline, 50% of the patients had cTnI and TBARS values outside the reference range. TNF-α, IL-6, IL-8 levels were within the reference range. Patients with cTnI above the RR clustered to significantly higher levels of TNF-α and IL-6. After contrast echocardiography, no statistically significant increase of cTnI, cytokines and TBARS was found. However, for nearly 50% of the patients, the intra-individual cTnI kinetics crossed the critical difference (threefold of methodical variation) which indicates a marker increase. This was neither predicted by the baseline levels of the cytokines nor the markers of oxidative stress.

Conclusion

There are no clinically relevant increases in serum markers for micro-necrosis, inflammation and oxidative stress in humans after contrast echocardiography. Future studies have to address whether cTnI increase in some patients represent a subset with increased risk for side effects after contrast echocardiography.

Increased reactive oxygen species production and functional alterations in antioxidant enzymes in human failing myocardium

BACKGROUND

The nature of oxidative stress and the activity of antioxidant enzyme systems are incompletely characterized in the failing human heart.

METHODS AND RESULTS

We obtained ventricular myocardium from failing, explanted human hearts in patients with nonischemic dilated cardiomyopathy at the time of heart transplant to examine whether reactive oxygen species (ROS) production and antioxidant enzyme activity or expression were altered in end-stage human heart failure. Nonfailing myocardium was obtained from organ donors who were not eligible for transplantation. Electroparamagnetic resonance (EPR) with the O(2)(-) spin trap 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide demonstrated that formation of superoxide anion was increased more than 2-fold in the failing (P < .001 vs. nonfailing) myocardium. Manganese superoxide dismutase (MnSOD) mRNA and catalase mRNA expression were increased by 52% (P=.05) and 116% (P < .05), respectively, in failing vs. nonfailing hearts. Copper-zinc superoxide dismutase (CuZnSOD) mRNA and glutathione peroxidase-1 (GPx-1) mRNA were unchanged. The expression of MnSOD, CuZnSOD, and catalase mRNA showed moderate correlation, suggesting coordinate regulation of gene expression. Activity was no different with regard to catalase, GPx-1, and glucose-6-phosphate dehydrogenase. MnSOD activity accounted for approximately 90% of total SOD activity, and was markedly decreased in failing hearts (by 61%, P < .05). MnSOD protein expression by western blot analysis was decreased in the failing group (P < .05 vs. nonfailing).

CONCLUSION

The decrease in MnSOD activity in failing myocardium, in the setting of increased mRNA expression, may reflect decreased translation or processing, or a posttranslational modification of MnSOD. The increase in MnSOD mRNA in failing hearts is consistent with the thesis that there is increased oxidative stress in failing myocardium that leads to increase transcription of antioxidant enzymes. The source of this direct measure of ROS is likely superoxide. These observations have implications for the pathophysiology and treatment of heart failure.

Relationship between oxidative stress and systolic dysfunction in patients with hypertrophic cardiomyopathy

BACKGROUND

Progression of hypertrophic cardiomyopathy (HCM) to left ventricular dilatation and systolic dysfunction sometimes occurs. However, the mechanism is not known. We examined whether oxidative stress was elevated in myocardia of HCM patients and whether the levels were correlated with left ventricular dilatation and systolic dysfunction.

METHODS AND RESULTS

Endomyocardial biopsy samples obtained from the right ventricular side of the septum of 31 patients with HCM, and 10 control subjects were studied immunohistochemically for the expression of 4-hydroxy-2-nonenal (HNE)-modified protein, which is a major lipid peroxidation product. Expression of HNE-modified protein was found in all myocardial biopsy samples from patients with HCM. Expression was distinct in the cytosol of cardiomyocytes. The expression levels in patients with HCM were significantly increased compared with those in control subjects (P = .0005). The expression levels in patients with HCM were correlated with left ventricular end-diastolic diameter (r = 0.483, P = .0053) and end-systolic diameter (r = 0.500, P = .0037) determined by echocardiography. The expression levels were inversely correlated with left ventricular ejection fraction determined by left ventriculography (r = -0.640, P = .0001).

CONCLUSION

Oxidative stress was elevated in myocardia of HCM patients and the levels were correlated with left ventricular dilatation and systolic dysfunction. Oxidative stress is involved in the pathogenesis of heart failure in patients with HCM.

Home-based exercise training modulates pro-oxidant substrates in patients with chronic heart failure

BACKGROUND

In chronic heart failure, oxidative stress is thought to lead to endothelial dysfunction. In this study, we assessed the effect of home-based exercise training on variables of the NO and purine pathways.

METHODS AND RESULTS

Eighteen patients and nine controls were randomly assigned in cross-over design to 8 weeks of exercise training (5 days/week, submaximal bicycle ergometer training, 30 min/day; calisthenics 9 min/day) and 8 weeks of sedentary lifestyle. Hypoxanthine, xanthine, l-arginine, asymmetric dimethylarginine (ADMA), symmetric DMA (SDMA) and nitrite were measured. In patients, exercise training led to an increase in peak VO(2) (p<0.003). At baseline hypoxanthine-a pro-oxidant substrate and marker of hypoxia-was higher in patients than in controls (24.6+/-4.3 vs. 11.9+/-4.2 micromol/l; p<0.05). After training there was a reduction in hypoxanthine (p<0.01). Nitrite levels were lower in patients (416+/-31 micromol/l) than in healthy controls (583+/-35 micromol/l, p<0.001). Although nitrite levels were highest after exercise, the changes did not reach statistical significance (p=n.s.). l-Arginine, ADMA, and SDMA levels were not different between groups and were not altered by exercise training.

CONCLUSIONS

Chronic heart failure is associated with increased levels of hypoxanthine and decreased levels of nitrite. This imbalance can be beneficially modulated by chronic home-based exercise training.

Uric acid in chronic heart failure

The pathophysiologic understanding of chronic heart failure (CHF) has shifted from a mere hemodynamic disorder to a much more complex approach including changes and imbalances in neurohormonal, immune, and metabolic functions. Among metabolic abnormalities, hyperuricemia is a constant finding in CHF. The xanthine oxidase metabolic pathway increasingly is appreciated as an important contributor to both symptoms of CHF as well as progression of the disease. Recent data suggest hyperuricemia to be an independent marker of impaired prognosis in CHF. In this article, the significance of the xanthine oxidase metabolic pathway in CHF is discussed. Data on xanthine oxidase inhibition are reviewed, which suggest a beneficial effect of therapeutically targeting this enzymatic pathway.

What causes sudden death in heart failure?

Patients with heart failure experience a number of changes in the electrical function of the heart that predispose to potentially lethal cardiac arrhythmias. Action potential prolongation, the result of functional downregulation of K currents, and aberrant Ca2+ handling is a recurrent theme. Significant alterations in conduction and activation of a number of initially adaptive but ultimately maladaptive signaling cascades contribute to the generation of a highly arrhythmogenic substrate. We review the changes in active and passive membrane properties, neurohumoral signaling, and genetic determinants that predispose to sudden arrhythmic death in patients with heart failure and highlight the critical unanswered questions that are ripe for future investigation.

Ventricular Arrhythmias Following Exposure of Failing Hearts to Oxidative Stress in Vitro

INTRODUCTION

There is experimental evidence that heart failure (HF) is an oxidative stress and that HF myocytes may be damaged by oxygen-derived free radicals. However, the arrhythmogenicity of these radicals has not been studied in HF.

METHODS AND RESULTS

Isolated perfused hearts were obtained from sham-operated (SHAM, n = 6), and fast pacing (250 ms, 2 weeks)-induced heart failure porcines (HF, n = 8). Epicardial conduction was mapped in the longitudinal and transverse directions and ventricular arrhythmias were closely monitored after perfusion of 100, 300, and 1000 micromol/L H(2)O(2). Left ventricular epicardium was sampled for action potentials recordings in the same conditions. Myocardial levels of thiobarbituric acid reactive substances and antioxidant enzymatic capacity were also assessed. Epicardial conduction velocities were unaffected by H(2)O(2) in both groups. Isolated ventricular premature beats and runs of slow ventricular rhythm with H(2)O(2) more frequently occurred in HF compared to SHAM despite an increased antioxidant capacity including Cu/Zn and Mn superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase. Sustained arrhythmias were not observed. Higher thiobarbituric acid reactive substances levels were found in HF confirming endogenous oxidative stress. Action potential duration at plateau level was increased following H(2)O(2) in SHAM but not in HF epicardial fibers where a toxic effect developed at 1000 micromol/L.

CONCLUSION

Oxidative stress with concomitant increase in antioxidant capacity develops in this HF model. There is a greater proclivity to oxidative stress-mediated arrhythmias in HF. These arrhythmias are mainly extrasystoles or slow ventricular rhythms and not dependent on abnormal myocardial conduction.

MESENTERIC VASCULAR DYSFUNCTION AFTER CARDIOPULMONARY BYPASS WITH CARDIAC ARREST IS AGGRAVATED BY COEXISTENT HEART FAILURE

Although patients suffering from heart failure (HF) have an increased incidence of nonocclusive mesenteric ischemia after opened heart surgery, the impact of cardiopulmonary bypass with cardiac arrest (CPB) on mesenteric vascular circulation in such situation remains unexplored. Therefore, the present study investigates the effects of CPB on mesenteric vascular reactivity, regional metabolism, and oxidative stress in an experimental model of HF. Volume-overload HF was induced in six dogs by bilateral femoral arteriovenous fistula. Six sham-operated dogs were used as controls. Eight weeks later, the short-term effects of 90 min of CPB were assessed in vivo during acute experiments. The significant increase in left ventricular end-diastolic volume in HF animals did not influence the vasodilator response of the superior mesenteric artery to acetylcholine (ACH) and nitroprusside (SNP) under baseline conditions. However, reduced mesenteric oxygen delivery, increased oxygen extraction, and lactate release were found during CPB in the HF group. In addition, an increased free radical production was assessed in the HF group during (89 +/- 23 x 10 relative light units [RLU]) and after CPB (93 +/- 15 x 10 RLU) compared with controls (45 +/- 15 and 49 +/- 7 x 10 RLU, respectively). Finally, 90 min of CPB led to a more pronounced decrease of ACH- (-22% +/- 5% vs. -42% +/- 9%, P < 0.05) and SNP- (-14% +/- 4% vs. -50% +/- 7%, P < 0.002) induced mesenteric vasodilations in the HF group compared with controls. We conclude that coexistent HF significantly enhances the pathological effects of CPB on the mesenteric vascular circulation by additionally altering endothelial and smooth muscle vascular function consequent to augmented oxidative stress.

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.

Novel pathophysiological insight and treatment strategies for heart failure--lessons from mice and patients--

The ultimate goal of heart failure (HF) treatment is to improve the prognosis of patients. Previous basic, clinical, and population studies have advanced the modern treatment of HF, but efficacy is still limited especially in 'real world' patients. There are 2 approaches to solve this crucial issue. First is the further development of novel therapeutic strategies based on new insight into the pathophysiology of myocardial remodeling and failure. Second is the improvement of the quality of care in routine clinical practice. The basic approach is to develop the treatment of myocardial remodeling by regulating mitochondrial oxidative stress. In the failing heart, oxygen radicals are the result of defects of mitochondrial electron transport, causing mitochondrial DNA damage and functional decline, and further production of oxygen radicals. Oxidative stress causes myocyte hypertrophy, apoptosis, and interstitial fibrosis by activating matrix metalloproteinases, all of which result in myocardial remodeling and failure. Therefore, mitochondrial oxidative stress and DNA damage are good therapeutic targets. The clinical approach is to develop effective strategies of HF management for the 'real world' patients. Readmission because of exacerbation is common in HF patients and further impairs their quality of life. Noncompliance with treatment is the most common precipitating factor for readmission. Regular medical follow-up and social support are important components that should be included in the disease management program of HF patients. These basic and clinical approaches are needed to establish new and effective treatment strategies for Japanese patients with HF.

Oxidative stress in atherogenesis and arterial thrombosis: the disconnect between cellular studies and clinical outcomes

Atherosclerosis is a multifactorial disease for which the molecular etiology of many of the risk factors is still unknown. As no single genetic marker or test accurately predicts cardiovascular death, phenotyping for markers of inflammation may identify the individuals at risk for vascular diseases. Reactive oxygen species (ROS) are key mediators of signaling pathways that underlie vascular inflammation in atherogenesis, starting from the initiation of fatty streak development through lesion progression to ultimate plaque rupture. Various animal models of atherosclerosis support the notion that ROS released from NAD(P)H oxidases, xanthine oxidase, lipoxygenases, and enhanced ROS production from dysfunctional mitochondrial respiratory chain indeed have a causatory role in atherosclerosis and other vascular diseases. Human investigations also support the oxidative stress hypothesis of atherogenesis. This is further supported by the observed impairment of vascular function and enhanced atherogenesis in animal models that have deficiencies in antioxidant enzymes. The importance of oxidative stress in atherosclerosis is further emphasized because of its role as a unifying mechanism across many vascular diseases. The main contraindicator for the role oxidative stress plays in atherosclerosis is the lack of effectiveness of antioxidants in reducing primary endpoints of cardiovascular death and morbidity. However, this lack of effectiveness by itself does not negate the existence or causatory role of oxidative stress in vascular disease. Lack of proven markers of oxidative stress, which could help to identify a subset of population that can benefit from antioxidant supplementation, and the complexity and subcellular localization of redox reactions, are among the factors responsible for the mixed outcomes in the use of antioxidants for the prevention of cardiovascular diseases. To better understand the role of oxidative stress in vascular diseases, future studies should be aimed at using advances in mouse and human genetics to define oxidative stress phenotypes and link phenotype with genotype.

Combination of isosorbide dinitrate and hydralazine in blacks with heart failure

BACKGROUND

We examined whether a fixed dose of both isosorbide dinitrate and hydralazine provides additional benefit in blacks with advanced heart failure, a subgroup previously noted to have a favorable response to this therapy.

METHODS

A total of 1050 black patients who had New York Heart Association class III or IV heart failure with dilated ventricles were randomly assigned to receive a fixed dose of isosorbide dinitrate plus hydralazine or placebo in addition to standard therapy for heart failure. The primary end point was a composite score made up of weighted values for death from any cause, a first hospitalization for heart failure, and change in the quality of life.

RESULTS

The study was terminated early owing to a significantly higher mortality rate in the placebo group than in the group given isosorbide dinitrate plus hydralazine (10.2 percent vs. 6.2 percent, P=0.02). The mean primary composite score was significantly better in the group given isosorbide dinitrate plus hydralazine than in the placebo group (-0.1+/-1.9 vs. -0.5+/-2.0, P=0.01; range of possible values, -6 to +2), as were its individual components (43 percent reduction in the rate of death from any cause [hazard ratio, 0.57; P=0.01] 33 percent relative reduction in the rate of first hospitalization for heart failure [16.4 percent vs. 22.4 percent, P=0.001], and an improvement in the quality of life [change in score, -5.6+/-20.6 vs. -2.7+/-21.2, with lower scores indicating better quality of life; P=0.02; range of possible values, 0 to 105]).

CONCLUSIONS

The addition of a fixed dose of isosorbide dinitrate plus hydralazine to standard therapy for heart failure including neurohormonal blockers is efficacious and increases survival among black patients with advanced heart failure.

Endothelial dysfunction and nitric oxide enhancing therapy: a new approach to the treatment of heart failure

Despite ethnic differences in heart failure prevalence, risk profiles, and outcomes, no clinical trials have been designed to prospectively examine the mechanisms responsible for these differences. The African-American Heart Failure Trial is the first prospective trial designed to test a novel therapy that enhances endothelial function and nitric oxide bioavailability in African-American patients with advanced heart failure.

Hydroxyl radical generation, levels of tumor necrosis factor-alpha, and progression to heart failure after acute myocardial infarction

OBJECTIVES

We used acetylsalicylic acid (ASA) as a probing agent to quantify hydroxyl radical ((*)OH) in Controls and patients with coronary artery disease and to prospectively investigate (*)OH production in patients with myocardial infarction (MI) complicated by heart failure (HF).

BACKGROUND

Oxidative stress status (OSS) is a mechanism for transition to HF in experimental heart injury models, but evidence for its causal role in humans is still limited.

METHODS

Thirty healthy subjects (Controls), 12 patients with stable angina (Group 1), and 74 patients with ST-segment elevation MI (Group 2) were enrolled. A dose of 250 mg Flectadol was given intravenously before each blood collection to determine the 2,3-dihydroxybenzoic acid/salicylic acid (DHBA/SA) ratio. We also quantified vitamin E and coenzyme Q(10) to monitor antioxidant reserve, as well as tumor necrosis factor (TNF)-alpha, TNF-soluble receptors, interleukin (IL)-6, and IL-1ra to assess inflammatory status. All measurements were repeated at month 6 in Group 2.

RESULTS

There were no differences between Controls and Group 1. Group 2 showed increased (*)OH production, peaking at 24 h, whereas vitamin E and coenzyme Q(10) progressively declined. Group 2 patients developing HF during hospitalization (Group 2Bi) presented with an increase of both (*)OH production at discharge and inflammatory status, as compared with patients without HF (Group 2Ai), persisting at month 6 in post-MI patients with HF (Group 2Bii).

CONCLUSIONS

We found a distinct pattern of (*)OH generation in post-MI patients who show progression to HF. The interplay between OSS and inflammatory status should be targeted as a possible mechanism of progression to post-MI left ventricular dysfunction.

Left ventricular mass increases with deteriorating glucose tolerance, especially in women: independence of increased arterial stiffness or decreased flow-mediated dilation: the Hoorn study

OBJECTIVE

Type 2 diabetes and impaired glucose metabolism (IGM) are associated with an increased cardiovascular disease (CVD) risk. Increased left ventricular mass (LVM) is thought to increase CVD risk through several unfavorable cardiac changes. Type 2 diabetes and IGM are associated with increased LVM, but the underlying mechanism is unclear. We investigated the association between glucose tolerance status (GTS) and LVM and explored whether any such association could be mediated through increased arterial stiffness, impaired endothelial function, or the presence of atherosclerosis.

RESEARCH DESIGN AND METHODS

We used ultrasound to measure LVM, carotid and femoral stiffness, carotid-femoral transit time, and flow-mediated vasodilation (FMD) and tonometry to estimate compliance and augmentation index. The study population (n = 780) consisted of 287 individuals with normal glucose metabolism (NGM), 179 with IGM, and 314 with type 2 diabetes, and the mean age was 68.4 years.

RESULTS

In women, after adjusting for age, height, BMI, and mean arterial pressure, LVM increased significantly with deteriorating GTS (LVM 157 g in NGM, 155 g in IGM, and 169 g in type 2 diabetes; P for trend <0.018). Additional adjustment for arterial stiffness, FMD, or the presence of atherosclerosis did not materially alter the results, even though these variables were significantly associated with both GTS and LVM. Indexes of hyperglycemia/-insulinemia or insulin resistance explained at most 7% of the association between GTS and LVM. In men, no statistically significant associations were observed.

CONCLUSIONS

Our data expand the conceptual view of the pathogenesis of GTS-related changes in LVM because we show that the increase in LVM in women is independent of increased arterial stiffness, impaired FMD, or the presence of atherosclerosis. In addition, we show that this increase in LVM is only minimally explained by indexes of hyperglycemia/-insulinemia or insulin resistance. Our data may, in part, explain the increased CVD risk seen in women with deteriorating GTS.

Intense lipid peroxidation in premature clinical coronary atherosclerosis is associated with metabolic abnormalities

Increased oxidative stress is associated with rapid progression of atherosclerosis. In this study we sought to determine whether premature onset of clinical coronary atherosclerosis is associated with increased levels of lipid peroxidation. We measured plasma levels of malondialdehyde (MDA), using high-pressure liquid chromatography, in 42 male patients with early- (<56 years) or late-onset (>64 years) unstable angina and in 2 age-matched control groups (n=20). Plasma MDA levels were higher in the patients with unstable angina than in the control groups (1.57 +/- 0.07 vs 1.14 +/- 0.03 nmol/mL; P<.001). Patients with early-onset angina showed higher MDA levels than those in late-onset patients (1.75 +/- 0.11 vs 1.44 +/- 0.097 nmol/mL; P<.05), despite a similar prevalence of risk factors for atherothrombosis. The inflammatory component, measured with the use of a high-sensitivity enzyme-linked immunosorbent assay for C-reactive protein, and platelet activity, measured as prothrombin fragment 1+2, failed to predict MDA level. Fasting glucose (P<.05) was the best predictor of MDA level in patients with early-onset unstable angina; uric acid (P=.09) and body-mass index (P=.15) showed trends toward significant correlation with MDA level in the same group of patients. Metabolic abnormalities related to insulin resistance in patients with premature coronary atherosclerosis appear to be important mediators of major plasma oxidative damage.

Determinants of platelet responsiveness to nitric oxide in patients with chronic heart failure

Congestive heart failure (CHF) is associated with oxidative stress. Platelet responsiveness to nitric oxide (NO) donors, are impaired in patients with angina pectoris, possibly by increasing oxidative stress. We investigated the occurrence of platelet resistance to NO in patients, with ischaemic or non-ischaemic cardiomyopathy compared with normal subjects. Anti-aggregatory effects of sodium nitroprusside (SNP), oxidative stress and whole blood superoxide anion content were determined, with correlates of responsiveness to SNP. Inhibition of platelet aggregation by SNP was 65.4+/-3.55% in controls and 59.3+/-4.1% in CHF (P=ns) despite increased oxidative stress and post-aggregation O2- in CHF patients. However, subsets of CHF patients have NO-resistant platelets: this is associated with increasing age and/or increased oxidative stress (both p<0.05).

Cardiac cachexia

Chronic heart failure (CHF) remains an important and increasing public health care problem. It is a complex syndrome affecting many body systems. Body wasting (i.e., cardiac cachexia) has long been recognised as a serious complication of CHF. Cardiac cachexia is associated with poor prognosis, independently of functional disease severity, age, and measures of exercise capacity and cardiac function. Patients with cardiac cachexia suffer from a general loss of fat tissue, lean tissue, and bone tissue. Cachectic CHF patients are weaker and fatigue earlier, which is due to both reduced skeletal muscle mass and impaired muscle quality. The pathophysiologic alterations leading to cardiac cachexia remain unclear, but there is increasing evidence that metabolic, neurohormonal and immune abnormalities may play an important role. Cachectic CHF patients show raised plasma levels of epinephrine, norepinephrine, and cortisol, and they show high plasma renin activity and increased plasma aldosterone level. Several studies have also shown that cardiac cachexia is linked to raised plasma levels of tumour necrosis factor alpha and other inflammatory cytokines. The degree of body wasting is strongly correlated with neurohormonal and immune abnormalities. The available evidence suggests that cardiac cachexia is a multifactorial neuroendocrine and metabolic disorder with a poor prognosis. A complex imbalance of different body systems may cause the development of body wasting.

Interaction of regular exercise and chronic nitroglycerin treatment on blood pressure and rat aortic antioxidants

Many cardiac patients undergo exercise conditioning with or without medication. Therefore, we investigated the interaction of exercise training and chronic nitroglycerin treatment on blood pressure (BP), aortic nitric oxide (NO), oxidants and antioxidants in rats. Fisher 344 rats were divided into four groups and treated as follows: (1) sedentary control, (2) exercise training (ET) for 8 weeks, (3) nitroglycerin (15 mg/kg, s.c. for 8 weeks) and (4) ET+nitroglycerin. BP was monitored with tail-cuff method. The animals were sacrificed 24 h after the last treatments and thoracic aorta was isolated and analyzed. Exercise training on treadmill for 8 weeks significantly increased respiratory exchange ratio (RER), aortic NO levels, and endothelial nitric oxide synthase (eNOS) protein expression. Training significantly enhanced aortic glutathione (GSH), reduced to oxidized glutathione (GSH/GSSG) ratio, copper/zinc-superoxide dismutase (CuZn-SOD), Mn-SOD, catalase (CAT), glutathione peroxidase (GSH-Px) glutathione disulfide reductase (GR) activities and protein expressions. Training significantly depleted aortic malondialdehyde (MDA) and protein carbonyls without change in BP. Nitroglycerin administration for 8 weeks significantly increased aortic NO levels and eNOS protein expression. Nitroglycerin significantly enhanced aortic Mn-SOD, CAT, GR and glutathione-S-transferase (GST) activities and protein expressions with decreased MDA levels, protein carbonyls and BP. Interaction of training and nitroglycerin treatment significantly increased aortic NO levels, eNOS protein expression, GSH/GSSG ratio, antioxidant enzymes and normalized BP. The data suggest that the interaction of training and nitroglycerin maintained BP by up-regulating the aortic NO and antioxidants and reducing the oxidative stress in rats.

Interaction of exercise training and chronic NOS inhibition on blood pressure, heart rate, NO and antioxidants in plasma of rats

Many individuals with cardiovascular diseases undergo periodic exercise conditioning with or without medication. Therefore, the purpose of this study was to examine the effect of exercise training on BP and HR under the condition of NOS inhibition and to clarify the mechanism of the effect in regard to oxidative stress, antioxidant enzyme activity, and NO production in the plasma of the rat. Fisher 344 rats were divided into four groups: (1) sedentary control, (2) exercise training for 8 weeks, (3) nitro-L-arginine methyl ester (L-NAME) (10mg/kg, s.c. for 8 weeks) and (4) ET + L-NAME. Blood pressure (BP) and heart rate (HR) were monitored weekly for 8 weeks. The animals were sacrificed 24h after last treatments, plasma isolated and analyzed. The results show that exercise conditioning resulted in enhanced NO production (120% of control), GSH levels (110% of control), GSH/GSSG ratio (124% of control) and the up-regulation of catalase (CAT) (225% of control), glutathione peroxidase (GSH-Px) (161% of control), glutathione reductase (GR) (142% of control) and glutathione-S-transferase (GST) (189% of control) and depression of malondialdehyde (MDA) (90% of control) and lactate (75% of control) in plasma of the rat. These biochemical changes were accompanied by no significant change in BP but slight increase in HR. Chronic L-NAME administration resulted in depression of NO (84% of control), GSH (90% of control), GSH/GSSG ratio (76% of control), the down-regulation of superoxide dismutase (SOD) (67% of control), GST (74% of control), and GR (90% of control). Plasma CAT and GSH-Px activities, MDA and lactate levels were significantly increased in L-NAME treated rats. The biochemical changes were accompanied by increase in blood pressure and heart rate. Interaction of exercise training and chronic NOS inhibitor treatment resulted in normalization of plasma NO levels, GSH/GSSG ratio, SOD and GST activities, and the up-regulation of, CAT, GSH-Px, and GR activities. The interaction resulted in depletion of plasma MDA levels compared to L-NAME treated group. The biochemical changes were accompanied by decrease in BP and HR compared to L-NAME treated group. The data suggest that the exercise training attenuated the oxidative injury caused by NOS inhibitor by increasing the plasma NO levels, GSH/GSSG ratio and up-regulating the antioxidant enzyme and lowering the BP and HR in the rat.

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.

Plasma thioredoxin levels and platelet aggregability in patients with acute myocardial infarction

BACKGROUND

Oxidative stress is thought to play an important role in atherosclerotic vascular disease. Recently, it has become possible to quantitatively measure thioredoxin, a marker of oxidative stress in human plasma. A platelet aggregometer that uses laser-light scattering enables minimal changes in platelet aggregability to be monitored; however, the relationship between oxidative stress and platelet aggregability in vivo is not well understood.

METHODS

We investigated plasma thioredoxin levels and platelet aggregability, in particular small platelet aggregates, in 45 patients with acute myocardial infarction (AMI); we compared the results with 33 patients with stable exertional angina (SEA) and 30 patients with chest pain syndrome (CPS).

RESULTS

The plasma thioredoxin levels and the degree of small platelet aggregates were higher in the AMI group than in the SEA and the CPS groups: in the AMI group, at 4 weeks after admission, both of those parameters were significantly decreased (P <.01), but they were still higher (P <.05) than in the SEA or the CPS group. There was a significant positive correlation between small platelet aggregates and plasma thioredoxin levels (rho = 0.354, P =.0002). We divided the AMI patients into 2 groups according to the 75 percentile of plasma thioredoxin levels on admission. At the chronic phase, the left ventricular ejection fraction was significantly higher in the lower thioredoxin group than in the higher thioredoxin group.

CONCLUSIONS

We showed that plasma thioredoxin levels and platelet aggregability increased concomitantly in patients with AMI. In these patients, increased plasma thioredoxin was associated with platelet hyperaggregability and lower left ventricular ejection fraction.

Increased myocardial NADPH oxidase activity in human heart failure

OBJECTIVES

This study was designed to investigate whether nicotinamide adenine dinucleotide 3-phosphate (reduced form) (NADPH) oxidase is expressed in the human heart and whether it contributes to reactive oxygen species (ROS) production in heart failure.

BACKGROUND

A phagocyte-type NADPH oxidase complex is a major source of ROS in the vasculature and is implicated in the pathophysiology of hypertension and atherosclerosis. An increase in myocardial oxidative stress due to excessive production of ROS may be involved in the pathophysiology of congestive heart failure. Recent studies have suggested an important role for myocardial NADPH oxidase in experimental models of cardiac disease. However, it is unknown whether NADPH oxidase is expressed in the human myocardium or if it has any role in human heart failure.

METHODS

Myocardium of explanted nonfailing (n = 9) and end-stage failing (n = 13) hearts was studied for the expression of NADPH oxidase subunits and oxidase activity.

RESULTS

The NADPH oxidase subunits p22(phox), gp91(phox), p67(phox), and p47(phox) were all expressed at messenger ribonucleic acid and protein level in cardiomyocytes of both nonfailing and failing hearts. NADPH oxidase activity was significantly increased in end-stage failing versus nonfailing myocardium (5.86 +/- 0.41 vs. 3.72 +/- 0.39 arbitrary units; p < 0.01). The overall level of oxidase subunit expression was unaltered in failing compared with nonfailing hearts. However, there was increased translocation of the regulatory subunit, p47(phox), to myocyte membranes in failing myocardium.

CONCLUSIONS

This is the first report of the presence of NADPH oxidase in human myocardium. The increase in NADPH oxidase activity in the failing heart may be important in the pathophysiology of cardiac dysfunction by contributing to increased oxidative stress.

Influence of vitamin C on baroreflex sensitivity in chronic heart failure

Chronic heart failure (CHF) reduces baroreflex sensitivity. Low baroreflex sensitivity, a risk factor for sudden death, could arise partly from CHF-dependent endothelial dysfunction. Vitamin C at high doses has a protective role against CHF-related endothelial damage. This study was conducted to investigate the effect of vitamin C on baroreflex sensitivity in CHF. A study group of 33 subjects with CHF secondary to postischemic dilated cardiomyopathy with an ejection fraction </=35% and a control group (11 subjects) underwent assessment of baroreflex sensitivity by the phenylephrine method and an autonomic nervous system study by power spectral analysis. Variables were assessed after infusion of placebo and high doses of vitamin C (2.5 mg). In subjects with CHF, baroreflex sensitivity was significantly higher after vitamin C than after placebo infusion (placebo: 4.1+/-0.4 versus vitamin C: 5.3+/-0.5 ms/mm Hg, P<0.001). Low-frequency of R-R (LFRR), expressed in normalized units (NU) (P<0.05); LF/high-frequency (HF) ratio (P<0.05), and LF of SBP (LFSBP) decreased significantly; HF power (P<0.05), and alpha-HF (P<0.001) increased. Conversely, in the control group, baroreflex sensitivity and other spectral variables measured at baseline, after placebo, and after vitamin C infusion remained statistically unchanged (placebo: 10.2+/-0.1 versus vitamin C: 10.0+/-0.2 ms/mm Hg, NS). Acute administration of vitamin C at high doses improves baroreflex sensitivity and vagal sinus modulation in patients with CHF. This finding could have notable clinical and therapeutic implications. Key issues to understand are whether the beneficial effect persists during chronic administration and whether it helps to improve survival.

Interaction of physical training and chronic nitroglycerin treatment on blood pressure and plasma oxidant/antioxidant systems in rats

Many individuals with cardiovascular diseases undergo periodic physical conditioning with or without medication. Therefore, this study investigated the interaction of exercise training and chronic nitroglycerin treatment on blood pressure (BP) and alterations in nitric oxide (NO), glutathione (GSH), antioxidant enzyme activities and lipid peroxidation in rats. Fisher 344 rats were divided into four groups: (1) sedentary control, (2) exercise training for 8 weeks, (3) nitroglycerin (15 mg/kg, s.c. for 8 weeks) and (4) training + nitroglycerin for 8 weeks. BP, heart rate (HR) and respiratory exchange ratio (RER) were monitored weekly for 8 weeks using tail-cuff method and oxygen/carbon dioxide analyzer, respectively. The animals were sacrificed 24 h after last treatments and plasma isolated and analyzed using HPLC, ELISA and UV-VIS spectrophotometric techniques. The results show that exercise conditioning significantly enhanced NO production (p < 0.001), GSH levels (p < 0.001), GSH/GSSG ratio (p < 0.05) and the up-regulation of the activities of catalase (CAT) (p < 0.05), glutathione peroxidase (GSH-Px) (p < 0.001), and glutathione reductase (GR) (p < 0.05), and depression of lactate levels (p < 0.001) in the plasma of the rat. These biochemical changes were accompanied by a significant increase in RER (p < 0.001) without a significant change in BP and HR. Chronic nitroglycerin administration significantly increased NO levels (p < 0.05), GSH levels (p < 0.001), superoxide dismutase (SOD) activity (p < 0.05), GST activity (p < 0.05), and decreased MDA levels (p < 0.05). These biochemical changes were accompanied by a significant decrease in BP (p < 0.05) and without any significant changes in HR and RER. Interaction of exercise training and chronic nitroglycerin treatment resulted in normalization of plasma NO, MDA, lactate levels, and CAT activity. The combination of exercise and nitroglycerin significantly enhanced GSH levels (p < 0.05), and the up-regulation of SOD (p < 0.001), GSH-Px (p < 0.05), GR (p < 0.05) and GST (p < 0.001) activities. These biochemical changes were accompanied by normalization of BP and a significant increased in RER (p < 0.001). The data suggest that the interaction of physical training and chronic nitroglycerin treatment resulted in the maintenance of BP and the up-regulation of plasma antioxidant enzyme activities and GSH levels in the rat.