Stress In Heart Failure Research Articles

Oxidative Stress in Heart Failure: What Are We Missing?

Over the past several decades, investigations in humans and animal models of heart failure (HF) have provided substantial evidence that oxidative stress is increased in HF and contributes to disease progression. The high metabolic activity of cardiac myocytes makes these cells active sources of reactive oxygen species. Work in cell and animal models clearly demonstrates that oxidative stress activates processes such as changes in gene expression and cell death that are now accepted components of myocardial remodeling and HF. Antioxidants prevent progressive remodeling and even improve cardiac function in animal models of HF. It is therefore disappointing that to date no antioxidant strategy has translated to a therapeutic in the HF clinic. Possible explanations, including inadequate appreciation of the critical disease-modifying sources of reactive oxygen species, the choice of the wrong antioxidant strategy, or incomplete understanding of individual variability in human antioxidant defenses in this brief review.

The role of stress in heart failure – ground for sex specific pathophysiology

In the last hundred years modern society went through numerous changes in life style, dietary habits, work load, physical activity and other environmental factors. As a species we are not well adapted to new de- mands. Higher levels of stress hormones provoke various effects, especially gradual change in the sensitivity of adrenergic, glucocorticoid and insulin receptors. All these changes are mutually associated and they gradually lead to metabolic syndrome, obesity, diabetes, heart failure and other types of pathology depending on genetic makeup and environmental factors. The aim of this paper is to summarize current knowledge concerning the impact of stress on cardiac function. Whereas stress response is sex specific we would emphasize a potential difference in pathophysiology of ischemic heart failure in men and women. Modern medicine has misinterpreted autonomous nervous system functions for years and this was reflected in heart failure (HF) and arterial hypertension therapy. Stress before the onset of menopause has a lesser effect on cardiac function compared to stress after menopause. Postmenopausal women have a significantly higher risk of heart disease, which is related to the diminished protection of the female hormonal cycle, but low doses of estrogen have not proven protective in postmenopausal women. Potential new targets of sex- specific cardiac therapy would come from better understanding of the molecular mechanisms exerted by nuclear receptors for steroid hormones, transcription factors involved in heart remodeling, cross-talk in adrenergic signaling pathways and their down-stream molecules.

Organ Protection from Oxidative Stress : a Role of Oxidative Stress in Heart Failure

心不全の発症機序については依然として不明な点が多い．近年，酸化ストレスマーカーと心不全重症度との相関の報告などにより，酸化ストレスの心不全発症への関与が示唆されるようになった．心臓での酸化ストレスの主因の一つと考えられる活性酸素種はスーパーオキシドである．スーパーオキシドは，スーパーオキシドディスムテース（SOD）と呼ばれる酵素により過酸化水素に代謝され，過酸化水素は，カタラーゼによりさらに酸素と水に代謝され無毒化される．このようにスーパーオキシドは各種活性酸素種の前駆体となる点でも重要である．最近では，その生体内産生機序として，NADPHオキシダーゼの役割が注目されている．スーパーオキシドレベルの相対的増大（＝酸化ストレス）の結果，心不全や心筋障害を発症するものと考えられる．現在までのところ，高血圧，糖尿病，肥満，炎症反応あるいは加齢など，一般に，心血管疾患のリスクファクターとなる病態でその可能性が明らかにされつつある．心臓での酸化ストレスを抑制する可能性がある薬剤として，スタチン，アンギオテンシンII受容体拮抗薬，ペルオキシゾーム増殖剤応答性受容体作用薬などがあげられる．しかしながら，麻酔薬が心臓への酸化ストレスを制御するか否かについては不明な点が多い．

Xanthine-oxidase inhibitors and statins in chronic heart failure: Effects on vascular and functional parameters

Increased oxidative stress in heart failure (HF) leads to inflammation and endothelial dysfunction (ED). Both statins and allopurinol have known anti-oxidant properties, but their utility in HF has not been fully assessed. This investigation was a prospective, double-blind, double-dummy study, performed between March 2007 and June 2009. Seventy-four HF patients, with New York Heart Association (NYHA) Class II or III status and left ventricular ejection fraction (LVEF) <40%, were included. Patients received placebo during 4 weeks and were then randomized to receive 4 weeks of either atorvastatin 20 mg/day plus placebo (ATV+PLA group) or atorvastatin 20 mg/day orally plus allopurinol 300 mg/day orally (ATV+ALLO group). Malondialdehyde (MDA), extracellular superoxide dismutase (ecSOD) activity and uric acid (UA) levels, among others, were determined at baseline and after 4 weeks of treatment. ED was assessed by flow-dependent endothelial-mediated vasodilation (FDD), and functional capacity by 6-minute walk test (6MWT). Thirty-two patients were randomized to ATV+PLA and 38 to ATV+ALLO. Mean age was 59 ± 2 years, 82% were male, and 22% had an ischemic etiology. Hypertension was present in 60% and diabetes in 15% of those studied. No significant differences were observed between baseline measurements and after placebo. After 4 weeks of treatment, both groups showed a significant decrease on MDA (0.9 ± 0.1 to 0.8 ± 0.1 and 1.0 ± 0.5 to 0.9 ± 0.1 μmol/liter, p = 0.88), UA (7.4 ± 0.4 to 6.8 ± 0.3 and 7.2 ± 0.4 to 5.0 ± 0.3 mg/dl, p < 0.01) and FDD (3.9 ± 0.2% to 5.6 ± 0.4% and 4.6 ± 0.3% to 7.1 ± 0.5%, p = 0.07) with increased ecSOD activity (109 ± 11 to 173 ± 13 and 98 ± 10 to 202 ± 16, U/ml/min, p = 0.41) and improved 6MWT (447 ± 18 to 487 ± 19 and 438 ± 17 to 481 ± 21 m, p = 0.83), with all values for ATV+PLA and ATV+ALLO, respectively; p-values are for comparison between groups after treatment. Short-term ATV treatment in heart failure (HF) patients reduces oxidative stress and improves FDD and functional capacity. These beneficial effects are not strengthened by the addition of allopurinol.

Predictors of oxidative stress in heart failure patients with Cheyne–Stokes respiration

Cheyne-Stokes respiration during sleep is associated with increased mortality in heart failure. The magnitude of oxidative stress is a marker of disease severity and a valuable predictor of mortality in heart failure. Increased oxidative stress associated with periodic breathing during Cheyne-Stokes respiration may mediate increased mortality in these patients. We hypothesized that the presence of Cheyne-Stokes respiration is associated with oxidative stress by increasing the formation of reactive oxygen species in patients with heart failure. Twenty-three patients with heart failure [left ventricular ejection fraction 30.2 ± 9% (mean ± standard deviation)] and 11 healthy controls underwent nocturnal polysomnography. Subjects with obstructive sleep apnea were excluded. The majority (88%) of patients with heart failure had Cheyne-Stokes respiration during sleep. The intensity of oxidative stress in neutrophils was greater in patients with heart failure (4,218 ± 1,706 mean fluorescence intensity/cell vs. 1,003 ± 348 for controls, p < 0.001) and correlated with the duration of Cheyne-Stokes respiration. Oxidative stress was negatively correlated with SaO(2) nadir during sleep (r = -0.43, p = 0.039). The duration of Cheyne-Stokes respiration predicted severity of oxidative stress in patients with heart failure (beta = 483 mean fluorescence intensity/cell, p < 0.02). Levels of oxidative stress are increased in patients with heart failure and Cheyne-Stokes respiration during sleep compared with healthy controls. The duration of Cheyne-Stokes respiration predicts the magnitude of oxidative stress in heart failure. Increased oxidative stress may mediate increased mortality associated with Cheyne-Stokes respiration in patients with heart failure.

Granulocyte colony‐stimulating factor in cardiac repair: time for a reappraisal?

This editorial refers to 'Granulocyte colony-stimulating factor attenuates left ventricular remodelling after acute anterior STEMI: results of the single-blind, randomized, placebo-controlled multicentre STem cEll Mobilization in Acute Myocardial Infarction (STEM-AMI) Trial' by F. Achilli et al., published in this issue on pages 1112―1122.

Cardiomyocyte NF-κB p65 promotes adverse remodelling, apoptosis, and endoplasmic reticulum stress in heart failure

the role of nuclear factor (NF)-κB in heart failure (HF) is not well defined. We sought to determine whether myocyte-localized NF-κB p65 activation in HF exacerbates post-infarction remodelling and promotes maladaptive endoplasmic reticulum (ER) stress. non-transgenic (NTg) and transgenic (Tg) mice with myocyte-restricted overexpression of a phosphorylation-resistant inhibitor of κBα (IκBα(S32A,S36A)) underwent coronary ligation (to induce HF) or sham operation. Over 4 weeks, the remote myocardium of ligated hearts exhibited robust NF-κB activation that was almost exclusively p65 beyond 24 h. Compared with sham at 4 weeks, NTg HF hearts were dilated and dysfunctional, and exhibited hypertrophy, fibrosis, up-regulation of inflammatory cytokines, increased apoptosis, down-regulation of ER protein chaperones, and up-regulation of the ER stress-activated pro-apoptotic factor CHOP. Compared with NTg HF, Tg-IκBα(S32A,S36A) HF mice exhibited: (i) improved survival, chamber remodelling, systolic function, and pulmonary congestion, (ii) markedly diminished NF-κB p65 activation, cytokine expression, and fibrosis, and (iii) a three-fold reduction in apoptosis. Moreover, Tg-IκBα(S32A,S36A) HF hearts exhibited maintained expression of ER chaperones and CHOP when compared with sham. In cardiomyocytes, NF-κB activation was required for ER stress-mediated apoptosis, whereas abrogation of myocyte NF-κB shifted the ER stress response to one of adaptation and survival. persistent myocyte NF-κB p65 activation in HF exacerbates cardiac remodelling by imparting pro-inflammatory, pro-fibrotic, and pro-apoptotic effects. p65 modulation of cell death in HF may occur in part from NF-κB-mediated transformation of the ER stress response from one of adaptation to one of apoptosis.

Hyperhomocystéinémie et stress oxydant chez les insuffisants cardiaques

Summary Background An imbalance between production of free radicals and oxidative protection in association with the coronary decease and their consequences such heart failure (HF). The aim of this study was to confirm the assumption of the impact of oxidative stress on patients with HF and hyperhomocyteinemia. Patient and method The study population included 60 patients with HF (71% were hyperhomocysteinemic) and 30 healthy controls subjects. Substances reacting with the acid thiobarbituric associated with the LDL (LDL TBARS) were determined by fluorimetric method, total status antioxidant (SAT) with colorimetric method and the glutathione peroxydase (GPx) was determined at 340 nm. Results Compared with healthy control subjects, patients with HF and hyperhomocyteinemia had statistically significant increase in the rate of LDL TBARS (p Conclusion Our study confirmed the hypothesis of implication of stress oxidative stress in HF with hyperhomocyteinemia.

Role of RAS Inhibition in the Regulation of Cu/Zn-SOD in the Cardiac and Peripheral Arterial Beds in Humans

Inhibition of the renin-angiotensin system (RAS) improves hemodynamics and may ameliorate oxidative stress in heart failure (HF). Through activation of nicotinamide adenine dinucleotide phosphate oxidase, angiotensin II induces superoxide, which is primarily cleared by cytosolic copper-zinc superoxide dismutase (Cu/Zn-SOD). We examined the interdependency of hemodynamics and levels of Cu/Zn-SOD and oxidized low-density lipoprotein (oxLDL) in HF patients, using a randomized, double-blinded, crossover design to compare (i) the outcomes of single-agent therapy with either benazepril or valsartan alone vs. the combination thereof and (ii) the outcome of single-agent treatment with benazepril vs. single-agent treatment with valsartan. After each treatment, arterial (ART) and coronary sinus (CS) blood samples were collected. Cu/Zn-SOD and oxLDL levels were higher in CS samples than in ART samples. Furthermore, patients under combined treatment exhibited the highest CS levels of Cu/Zn-SOD, whereas there was no significant difference between the groups on either benazepril or valsartan alone. This finding suggests an augmentation of the cardiac antioxidative potential under more complete RAS inhibition. Cu/Zn-SOD and oxLDL levels correlated with measures of afterload rather than preload, which in turn suggests a beneficial effect of afterload reduction on oxidative stress in HF.

MnSOD protects against COX1-mediated endothelial dysfunction in chronic heart failure

Endothelial function is impaired by oxidative stress in chronic heart failure (HF). Mechanisms that protect against increases in oxidative stress in HF are not clear. The goal of this study was to determine whether manganese superoxide dismutase (MnSOD) plays a key role in protecting against endothelial dysfunction in HF. Endothelial function and gene expression were examined in aorta from wild-type mice (MnSOD(+/+)) and mice deficient in MnSOD (MnSOD(+/-)) 12 wk after ligation of the left coronary artery (LCA). LCA ligation produced similar size myocardial infarctions in MnSOD(+/+) and MnSOD(+/-) mice and reduced ejection fraction to approximately 20% in both groups. Maximal relaxation in response to acetylcholine was 78 +/- 3% (mean +/- SE) and 66 +/- 8% in sham-operated MnSOD(+/+) and MnSOD(+/-) mice, respectively. Expression of antioxidant enzymes increased in MnSOD(+/+) mice with HF, and maximal relaxation to acetylcholine was slightly impaired (68 +/- 4%). Greater endothelial dysfunction was observed in MnSOD(+/-) mice with HF (46 +/- 5%, P < 0.05), which was significantly improved by polyethylene glycol-catalase but not Tempol. Incubation with the nonspecific cyclooxygenase (COX) inhibitor indomethacin or the COX1 inhibitor valeryl salicylate, but not the COX-2 inhibitor NS-398, significantly improved relaxation to acetylcholine in HF mice (maximum relaxation = 74 +/- 5, 91 +/- 1, and 58 +/- 5%). These data suggest that MnSOD plays a key role in protecting against endothelial dysfunction in HF. A novel mechanism was identified whereby chronic increases in oxidative stress, produced by mitochondrial SOD deficiency, impair vascular function via a hydrogen peroxide-dependent, COX1-dependent, endothelium-derived contracting factor.

Hypoxia, Not the Frequency of Sleep Apnea, Induces Acute Hemodynamic Stress in Patients With Chronic Heart Failure

This study was conducted to evaluate whether brain (B-type) natriuretic peptide (BNP) changes during sleep are associated with the frequency and severity of apneic/hypopneic episodes, intermittent arousals, and hypoxia. Sleep apnea is strongly associated with heart failure (HF) and could conceivably worsen HF through increased sympathetic activity, hemodynamic stress, hypoxemia, and oxidative stress. If apneic activity does cause acute stress in HF, it should increase BNP. Sixty-four HF patients with New York Heart Association functional class II and III HF and ejection fraction <40% underwent a baseline sleep study. Five patients with no sleep apnea and 12 with severe sleep apnea underwent repeat sleep studies, during which blood was collected every 20 min for the measurement of BNP. Patients with severe sleep apnea also underwent a third sleep study with frequent BNP measurements while they were administered oxygen. This provided 643 observations with which to relate apnea to BNP. The association of log BNP with each of 6 markers of apnea severity was evaluated with repeated measures regression models. There was no relationship between BNP and the number of apneic/hypopneic episodes or the number of arousals. However, the burden of hypoxemia (the time spent with oxygen saturation <90%) significantly predicted BNP concentrations; each 10% increase in duration of hypoxemia increased BNP by 9.6% (95% confidence interval: 1.5% to 17.7%, p = 0.02). Hypoxemia appears to be an important factor that underlies the impact of sleep abnormalities on hemodynamic stress in patients with HF. Prevention of hypoxia might be especially important for these patients.

Biomarkers of Oxidative Stress in Heart Failure

Oxidative stress is the relative excess of reactive oxygen species (ROS) versus endogenous defense mechanisms. Abundant evidence has demonstrated the role of ROS, along with reactive nitrogen species (RNS), in the pathophysiology of cardiovascular disease, including heart failure. Many biomarkers of oxidative stress have been studied as surrogates of oxidative damage. Recently, markers of impaired nitric oxide signaling have also been identified. Many biomarkers have been associated with prognosis and mortality, and some may even be modified by therapy. However, the clinical utility is limited by less than optimal standardization techniques and the lack of sufficient large-sized, multimarker prospective trials.

4-Hydroxy-2-nonenal Induces Calcium Overload via the Generation of Reactive Oxygen Species in Isolated Rat Cardiac Myocytes

Background It has been reported that that the amount of 4-hydroxy-2-nonenal (HNE), which is a major lipid peroxidation product and a cytotoxic aldehyde, is increased in the human failing myocardium. This study was designed to determine whether HNE has a pro-oxidant effect in cardiac myocytes and whether HNE causes Ca 2+ overload. Methods and Results Exposure to HNE for 10 minutes in the presence of ferric nitrilotriacetate induced the production of hydroxyl radical (·OH) in the rat myocardium as assessed by electron spin resonance spectroscopy, and HNE induced the generation of reactive oxygen species (ROS) in a dose-dependent manner as assessed by 2′, 7′-dichlorofluorescein diacetate fluorescence. HNE increased intracellular Ca 2+ concentration ([Ca 2+] i) as assessed by fura-2 ratio in a dose- and time-dependent manner. After 20 minutes of HNE (400 μmol/L) exposure, hypercontracture was induced in 67% of the cells. Catalase, an antioxidative enzyme that can decompose hydrogen peroxide (H 2O 2), significantly attenuated the increase in [Ca 2+] i and completely inhibited hypercontracture. Carvedilol, a β-blocker with potent antioxidant activity, also significantly attenuated the increase in [Ca 2+] i and completely inhibited hypercontracture, but propranolol had no effect on either [Ca 2+] i increase or hypercontracture. Conclusions HNE induces the formation of ROS, especially H 2O 2 and ·OH, in cardiomyocytes and subsequently ROS cause intracellular Ca 2+ overload. HNE formation may play an important role as a mediator of oxidative stress in heart failure.

Redox Modification of Ryanodine Receptors Contributes to Sarcoplasmic Reticulum Ca 2+ Leak in Chronic Heart Failure

Abnormal cardiac ryanodine receptor (RyR2) function is recognized as an important factor in the pathogenesis of heart failure (HF). However, the specific molecular causes underlying RyR2 defects in HF remain poorly understood. In the present study, we used a canine model of chronic HF to test the hypothesis that the HF-related alterations in RyR2 function are caused by posttranslational modification by reactive oxygen species generated in the failing heart. Experimental approaches included imaging of cytosolic ([Ca(2+)](c)) and sarcoplasmic reticulum (SR) luminal Ca(2+) ([Ca(2+)]SR) in isolated intact and permeabilized ventricular myocytes and single RyR2 channel recording using the planar lipid bilayer technique. The ratio of reduced to oxidized glutathione, as well as the level of free thiols on RyR2 decreased markedly in failing versus control hearts consistent with increased oxidative stress in HF. RyR2-mediated SR Ca(2+) leak was significantly enhanced in permeabilized myocytes, resulting in reduced [Ca(2+)](SR) in HF compared to control cells. Both SR Ca(2+) leak and [Ca(2+)](SR) were partially normalized by treating HF myocytes with reducing agents. Conversely, oxidizing agents accelerated SR Ca(2+) leak and decreased [Ca(2+)](SR) in cells from normal hearts. Moreover, exposure to antioxidants significantly improved intracellular Ca(2+)-handling parameters in intact HF myocytes. Single RyR2 channel activity was significantly higher in HF versus control because of increased sensitivity to activation by luminal Ca(2+) and was partially normalized by reducing agents through restoring luminal Ca(2+) sensitivity oxidation of control RyR2s enhanced their luminal Ca(2+) sensitivity, thus reproducing the HF phenotype. These findings suggest that redox modification contributes to abnormal function of RyR2s in HF, presenting a potential therapeutic target for treating HF.

Circulating white blood cells and platelets amplify oxidative stress in heart failure

Mitochondria of circulating white blood cells (WBC) and platelets sense oxidative stress during capillary passage and react by producing reactive oxygen species (ROS). Although evidence indicates that congestive heart failure (CHF) is associated with oxidative stress, the role of WBC and platelets as mediators in CHF has not been investigated. Patients with CHF (n = 15) and healthy volunteers (n = 9) were enrolled between 2006 and 2007 into this observational study. Arterial and venous blood samples from participants were incubated with probes to detect cytosolic and mitochondrial ROS. Fluorescence-activated cell sorting was used to measure the degree of fluorescence in WBC and platelets. Patients with CHF had a higher proportion of ROS-positive arterial WBC and platelets than did controls (67% +/- 47% versus 16% +/- 9%; P <0.005), as well as venous WBC and platelets (77% +/- 43% versus 38% +/- 13%; P <0.01). In the control group, the proportion of cytosolic ROS-positive arterial WBC and platelets was lower than that for ROS-positive venous WBC and platelets (16% +/- 9% versus 38% +/- 13%; P <0.005). CHF patients had a higher proportion of mitochondrial ROS-positive arterial and venous WBC and platelets than did controls. In CHF, the proportion of WBC and platelets that are ROS-positive is raised, possibly because cytosolic ROS-positive WBC and platelets are normally cleared in the lungs; this function is deficient in CHF while mitochondrial ROS production is increased. The raised numbers of circulating ROS-positive WBC and platelets amplify oxidative stress in CHF.

Retracted: The correlation between angiogenesis and abnormal expression of SERCA2a, phospholamban and the endothelin pathway in heart failure, and improvement by puerarin

Emerging evidence indicates that angiogenesis may be a potential new target in treating heart failure (HF). It was hypothesized that a lack of angiogenesis would correlate with an abnormal expression of sarco/endoplasmic reticulum ATPase 2a (SERCA2a) and phospholamban (PLB), and the activated endothelin (ET) pathway and oxidative stress in HF. If this is the case, such normal changes could be reversed by puerarin. HF was produced by coronary artery ligation for 4 weeks in rats. The rats were divided into three groups: sham, HF untreated and HF + puerarin (120 mg/kg per day, i.p.). Hemodynamic and echocardiographic changes, angiogenesis, cardiac morphology, serum biochemistry, mRNA and proteins of the angiogenesis pathway, the ET pathway and redox were measured. In the HF rats, hemodynamic and echocardiographic abnormalities, cardiac remodeling and histological changes with features of cardiac failure were associated with a lack of the angiogenesis pathway, accompanied by oxidative stress, an up-regulated ET pathway and abnormal SERCA2a and PLB expressions in HF rats. Puerarin significantly promoted angiogenesis and reversed the above changes. In conclusion, the absence of the angiogenesis pathway correlated with abnormal expression of SERCA2a and PLB and an activated ET-ROS (reactive oxygen species) system in the affected myocardium. Puerarin promoted the angiogenesis pathway, improved myocardial microcirculation and down-regulated the ET system, resulting in a reversal of the abnormalities of expression of SERCA2a and PLB, and the cardiac performance in HF.

Intracellular devastation in heart failure

End-stage heart failure is characterized by a number of abnormalities at the cellular level, which include changes in excitation-contraction coupling, alterations in contractile proteins and activation/deactivation of signaling pathways. Even though many of these changes are adaptive to the high workload and stress in heart failure, a significant number of these alterations are deeply deleterious to the cardiac cell. In this article, we will review the changes in calcium cycling that occur in myopathic hearts and how they can be effectively targeted. We will also focus on protein misfolding in the setting of cardiac dysfunction.

Assessment and relevance of ventricular wall stress in heart failure

We read with great interest the article by De Simone et al. 1, published in the European Heart Journal . By using M-mode echocardiography, the authors examined the relationship between left ventricular (LV) mass and incident heart failure not attributable to myocardial infarction. LV hypertrophy (LVH) or ‘excess’ of LV mass was found to be an independent predictor of incident heart failure. To quantify this so-called ‘excess’ of LV mass, expected normal values were calculated based on body height, gender, and stroke work. The latter was defined by …

Contribution of brain nuclear factor‐kappa B to the pathogenesis of heart failure

Previous studies have shown nuclear factor kappa B (NF‐κB) is a major mediator facilitating the synthesis of proinflammatory cytokines (PIC) both in the peripheral and central nervous system. In this study we determined, whether blockade of brain NF‐κB attenuates PIC and oxidative stress in heart failure (HF) rats. Adult male Sprague‐Dawley rats were implanted with intracerebroventricular (ICV) cannulae and subjected to coronary artery ligation to induce HF or sham surgery (SHAM). Subsequently, animals were ICV treated with SN50 (2μg/hr), a membrane permeable peptide which inhibits nuclear translocation of NF‐κB, or vehicle (VEH) for 4 weeks. HF‐induced increases in the expression of NF‐κB, AT1‐R and NADPH oxidase gene in paraventricular nucleus (PVN) of hypothalamus, and TNF‐α, IL‐1β, IL‐6 and angiotensin type 1 receptor (AT1‐R) in hypothalamus compared with sham rats. The HF rats also had increased plasma norepinephrine (NE), an indirect indicator of sympathetic activity. In contrast, ICV treatment with SN50 attenuated the expression of PIC, NF‐κB, AT1‐R and oxidative stress gene in the PVN compared with VEH‐treated HF rats. Treatment with SN50 also reduced plasma levels of NE, angiotensin II (ANG II) and PIC, and lung weight to body weight ratio. These findings suggest NF‐κB may be one key mediator stimulating the synthesis of brain RAS and PIC in HF.

Enhanced myocardial vitamin C accumulation in left ventricular hypertrophy in rats is not attenuated with transition to heart failure

Indirect observations are compatible with cardiac vitamin C deficiency as one contributory factor to oxidative stress in heart failure, but data on ventricular vitamin C content are lacking. Here, we used the well established model of aortic-banded rats at the stage of compensated hypertrophy (6 weeks after banding) and at the transition to cardiac failure (22 weeks after banding) to analyze vitamin C, vitamin E, protein carbonyls and malondialdehyde tissue content together with the respective plasma concentrations. Furthermore, we investigated the expression of the vitamin C transporters SVCT1 and SVCT2 in the left ventricle (LV). Aortic-banded rats, independently from their age, had higher malondialdehyde and protein carbonyl levels in plasma and LV tissue compared to sham-operated animals indicating increased oxidative stress. Plasma vitamin C remained unaffected from cardiac overload, while LV vitamin C was elevated in both stages of hypertrophy together with an increased expression of the vitamin C transporter SVCT2 suggesting increased vitamin C uptake. The levels of antioxidants and lipid peroxides were similar 6 and 22 weeks after aortic banding. Therefore, the accumulation of vitamin C in compensated hypertrophy and in decompensated failure excludes cardiac vitamin C deficiency as a primary factor to oxidative stress in this model.