Adverse effects of free fatty acid associated with increased oxidative stress in postischemic isolated rat hearts

Free fatty acids: independent predictors of long-term adverse cardiovascular outcomes in heart failure patients

BACKGROUND

The association between plasma free fatty acid (FFA) and the outcomes in the heart failure (HF) patients remains unclear.

METHODS

A cohort study among HF patients was performed. Plasma FFA was analyzed as both a continuous and a categorical variable (grouped by tertiles) to assess its association with composite cardiovascular (CV) death and HF hospitalization (CV death & HHP), CV death alone, and all-cause mortality (ACM) using Cox regression models. Subgroup analyses of HF patients with preserved ejection fraction (HFpEF) and mildly reduced/reduced ejection fraction (HFmrEF/HFrEF) were performed. This work also assessed the effectiveness of combining FFA and NT-pro BNP biomarkers for risk stratification by calculating the concordance index (C-index).

RESULTS

Among the 4,109 HF patients, FFA levels exceeding 0.4-0.42 mmol/L were associated with increased risks of the three outcomes. Patients in the highest FFA tertile faced greater risks than those in the lowest tertile. Adjusted hazard ratios were 1.32 (95% CI: 1.11-1.58) for CV death & HHP, 1.45 (95% CI: 1.16-1.82) for CV death, and 1.39 (95% CI: 1.15-1.68) for ACM, with a maximum follow-up of 8 years (median: 25 months). Subgroup analyses revealed that elevated FFA levels consistently predicted worse outcomes in both HFmrEF/HFrEF and HFpEF patients. The C-index for predicting outcomes was significantly greater when NT-pro BNP and FFA were combined than when NT-pro BNP was used alone (P < 0.01).

CONCLUSION

Increased plasma FFA concentrations were independently associated with greater risks of CV death & HHP, CV death, and ACM among HF patients, irrespective of the ejection fraction. The combination of FFA and NT-pro BNP biomarkers significantly improved risk stratification in HF patients.

Association between Serum Free Fatty Acids and Clinical and Laboratory Parameters in Acute Heart Failure Patients

Very little is known about the association between individual serum free fatty acids (FFAs) and clinical and laboratory parameters (indicators of heart failure severity) in acute heart failure (AHF) patients. Here, the baseline serum levels of FFAs, 16:0 (palmitic acid), 16:1 (palmitoleic acid), 18:0 (stearic acid), 18:1 (oleic acid), 18:2 (linoleic acid), 18:3 (alpha-linolenic acid or gamma-linolenic acid), 20:4 (arachidonic acid), 20:5 (eicosapentaenoic acid), and 22:6 (docosahexaenoic acid), were determined in 304 AHF patients (94.7% belonged to New York Heart Association functional class IV) using gas chromatography. Spearman correlation coefficients were used to examine the associations between the individual and total (the sum of all FFAs) FFAs and clinical and laboratory parameters. After applying a Bonferroni correction to correct for multiple testing, the total FFAs, as well as the individual FFAs (except FFAs 18:0, 20:5, and 22:6), were found to be significantly positively correlated with serum albumin. Only a few additional associations were found: FFA 16:0 was significantly negatively correlated with systolic pulmonary artery pressure, FFA 18:3 was significantly negatively correlated with C-reactive protein and body mass index, and FFA 20:4 was significantly negatively correlated with blood urea nitrogen. Based on our results, we conclude that in patients with severe AHF, individual and total serum FFAs are slightly associated with established laboratory and clinical parameters, which are indicators of heart failure severity.

Regulatory effects of trimetazidine in cardiac ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury is a tissue damage during reperfusion after an ischemic condition. I/R injury is induced by pathological cases including stroke, myocardial infarction, circulatory arrest, sickle cell disease, acute kidney injury, trauma, and sleep apnea. It can lead to increased morbidity and mortality in the context of these processes. Mitochondrial dysfunction is one of the hallmarks of I/R insult, which is induced via reactive oxygen species (ROS) production, apoptosis, and autophagy. MicroRNAs (miRNAs, miRs) are non-coding RNAs that play a main regulatory role in gene expression. Recently, there are evidence, which miRNAs are the major modulators of cardiovascular diseases, especially myocardial I/R injury. Cardiovascular miRNAs, specifically miR-21, and probably miR-24 and miR-126 have protective effects on myocardial I/R injury. Trimetazidine (TMZ) is a new class of metabolic agents with an anti-ischemic activity. It has beneficial effects on chronic stable angina by suppressing mitochondrial permeability transition pore (mPTP) opening. The present review study addressed the different mechanistic effects of TMZ on cardiac I/R injury. Online databases including Scopus, PubMed, Web of Science, and Cochrane library were assessed for published studies between 1986 and 2021. TMZ, an antioxidant and metabolic agent, prevents the cardiac reperfusion injury by regulating AMP-activated protein kinase (AMPK), cystathionine-γ-lyase enzyme (CSE)/hydrogen sulfide (H2S), and miR-21. Therefore, TMZ protects the heart against I/R injury by inducing key regulators such as AMPK, CSE/H2S, and miR-21.

Discovery of Antibacterial Contezolid Acefosamil: Innovative O-Acyl Phosphoramidate Prodrug for IV and Oral Therapies

New oral antibiotic contezolid (CZD) is effective against Gram-positive infections but unsuitable for intravenous (IV) administration due to its modest solubility. To address the medical need for an IV form of CZD, its isoxazol-3-yl phosphoramidate derivatives have been explored, and contezolid acefosamil (CZA, 8), the first representative of a novel O-acyl phosphoramidate prodrug class, has been identified. CZA exhibits high aqueous solubility (>200 mg/mL) and good hydrolytic stability at media pH suitable for IV administration. CZA rapidly converts into the active drug CZD in vivo. In a pharmacokinetic (PK) rat model, the exposure of active drug CZD after IV administration of the prodrug CZA was similar to or higher than that from the IV administration of CZD. The prodrug CZA is bioequivalent to or better than CZD in several preclinical infection models. CZA is likewise active upon its oral administration. To date, CZA has been evaluated in Phase 1 and Phase 2 clinical trials in the USA. It is advancing into further clinical studies including step-down therapy with in-hospital intravenous CZA administration followed by outpatient oral CZD treatment.

Serum concentrations of free fatty acids are associated with 3-month mortality in acute heart failure patients

Background

Plasma free fatty acids (FFA) are higher in heart failure (HF) patients compared to healthy controls. Considering that the extent of FFA elevation in HF might mirror the severity of HF, we hypothesized that the serum levels of FFA may be a useful prognostic indicator for 3-month mortality in acute heart failure (AHF).

Methods

We analyzed the serum samples of AHF patients obtained at admission to the emergency department. Serum levels of FFA were analyzed using an enzymatic reagent on an automatic analyzer.

Results

Out of 152 included AHF patients that were originally included, serum samples of 132 patients were available for the quantification of FFA. Of these, 35 (26.5%) died within 3 months of onset of AHF. These patients had significantly higher serum levels of FFA compared to AHF patients who were alive 3 months after onset of AHF. Univariable logistic regression analyses showed a significant positive association of FFA levels with 3-month mortality (odds ratio [OR] 2.76 [95% confidence interval 1.32–6.27], p = 0.010). Importantly, this association remained significant after adjusting for age and sex, as well as for further clinical and laboratory parameters that showed a significant association with 3-month mortality in the univariate analyses.

Conclusions

We conclude that the admission serum levels of FFA are associated with 3-month mortality in AHF patients. Therefore, measurements of circulating FFA levels may help identifying high-risk AHF patients.

Diet-induced obese mouse hearts tolerate an acute high-fatty acid exposure that also increases ischemic tolerance

An ischemic insult is accompanied by an acute increase in circulating fatty acid (FA) levels, which can induce adverse changes related to cardiac metabolism/energetics. Although chronic hyperlipidemia contributes to the pathogenesis of obesity-/diabetes-related cardiomyopathy, it is unclear how these hearts are affected by an acute high FA-load. We hypothesize that adaptation to chronic FA exposure enhances the obese hearts' ability to handle an acute high FA-load. Diet-induced obese (DIO) and age-matched control (CON) mouse hearts were perfused in the presence of low- or high FA-load (0.4 and 1.8 mM, respectively). Left ventricular (LV) function, FA oxidation rate, myocardial oxygen consumption, and mechanical efficiency were assessed, followed by analysis of myocardial oxidative stress, mitochondrial respiration, protein acetylation, and gene expression. Finally, ischemic tolerance was determined by examining LV functional recovery and infarct size. Under low-FA conditions, DIO hearts showed mild LV dysfunction, oxygen wasting, mechanical inefficiency, and reduced mitochondrial OxPhos. High FA-load increased FA oxidation rates in both groups, but this did not alter any of the above parameters in DIO hearts. In contrast, CON hearts showed FA-induced mechanical inefficiency, oxidative stress, and reduced OxPhos, as well as enhanced acetylation and activation of PPARα-dependent gene expression. While high FA-load did not alter functional recovery and infarct size in CON hearts, it increased ischemic tolerance in DIO hearts. Thus, this study demonstrates that acute FA-load affects normal and obese hearts differently and that chronically elevated circulating FA levels render the DIO heart less vulnerable to the disadvantageous effects of an acute FA-load.NEW & NOTEWORTHY An acute myocardial fat-load leads to oxidative stress, oxygen wasting, mechanical inefficiency, hyperacetylation, and impaired mitochondrial function, which can contribute to reduced ischemic tolerance. Following obesity/insulin resistance, hearts were less affected by a high fat-load, which subsequently also improved ischemic tolerance. This study highlights that an acute fat-load affects normal and obese hearts differently and that obesity renders hearts less vulnerable to the disadvantageous effects of an acute fat-load.

Long-chain free fatty acids inhibit ischaemic preconditioning of the isolated rat heart

We recently reported that non-preconditioned hearts from diet-induced obese rats showed, compared to controls, a significant reduction in infarct size after ischaemia/reperfusion, whilst ischaemic preconditioning was without effect. In view of the high circulating FFA concentration in diet rats, the aims of the present study were to: (i) compare the effect of palmitate on the preconditioning potential of hearts from age-matched controls and diet rats (ii) elucidate the effects of substrate manipulation on ischaemic preconditioning. Substrate manipulation was done with dichloroacetate (DCA), which enhances glucose oxidation and decreases fatty acid oxidation. Isolated hearts from diet rats, age-matched controls or young rats, were perfused in the working mode using the following substrates: glucose (10 mM); palmitate (1.2 mM)/3% albumin) + glucose (10 mM) (HiFA + G); palmitate (1.2 mM/3% albumin) (HiFA); palmitate (0.4 mM/3% albumin) + glucose(10 mM) (LoFA + G); palmitate (0.4 mM/3% albumin) (LoFA). Hearts were preconditioned with 3 × 5 min ischaemia/reperfusion, followed by 35 min coronary ligation and 60 min reperfusion for infarct size determination (tetrazolium method) or 20 min global ischaemia/10 or 30 min reperfusion for Western blotting (ERKp44/42, PKB/Akt). Preconditioning of glucose-perfused hearts from age-matched control (but not diet) rats reduced infarct size, activated ERKp44/42 and PKB/Akt and improved functional recovery during reperfusion (ii) perfusion with HiFA + G abolished preconditioning and activation of ERKp44/42 (iii) DCA pretreatment largely reversed the harmful effects of HiFA. Hearts from non-preconditioned diet rats exhibited smaller infarcts, but could not be preconditioned, regardless of the substrate. Similar results were obtained upon substrate manipulation of hearts from young rats. Abolishment of preconditioning in diet rats may be due to altered myocardial metabolic patterns resulting from changes in circulating FA. The harmful effects of HiFA were attenuated by stimulation of glycolysis and inhibition of FA oxidation.

Significance of plasma free fatty acid level for assessing and diagnosing acute myocardial infarction

Aim: To clarify the diagnostic value of the circulating free fatty acid (FFA) level for acute myocardial infarction (AMI) in coronary heart disease patients. Methods & results: A total of 1776 patients were screened by coronary angiography from October 2014 to February 2016. The plasma FFA level was significantly higher in coronary heart disease patients with lesions in three or more vessels than those with lesions in one or two vessels. Moreover, an elevated FFA level was identified as an independent risk factor for AMI on multivariate regression analysis and shown to be a sensitive and specific indicator for AMI diagnosis by receiver operating characteristic curve analysis. Conclusion: An elevated FFA level is an independent risk factor and independent diagnostic marker for AMI.

Oxidative and endoplasmic reticulum stresses are involved in palmitic acid-induced H9c2 cell apoptosis

Palmitic acid (PA) is the most common saturated long-chain fatty acid that causes damage to heart muscle cells. However, the molecular mechanism of PA toxicity in myocardial cells is not fully understood. In the present study, we explored the effects of PA on proliferation and apoptosis of H9c2 cardiomyocytes, and uncovered the signaling pathways involved in PA toxicity. Our study revealed induction of both oxidative and endoplasmic reticulum (ER) stresses and exacerbation of apoptosis in PA-treated H9c2 cells. Inhibition of oxidative stress by N-acetylcysteine (NAC) reduced apoptosis and decreased ER stress in PA-treated H9c2 cells. Moreover, inhibition of ER stress by 4-phenyl butyric acid decreased apoptosis and attenuated oxidative stress. In summary, the present study demonstrated that oxidative stress coordinates with ER stress to play important roles in PA-induced H9c2 cell apoptosis.

Direct free radical scavenging effects of water-soluble HMG-CoA reductase inhibitors

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, statins, are widely used for preventing cardiovascular and cerebrovascular diseases by controlling blood cholesterol level. Additionally, previous studies revealed the scavenging effects of statins on free radicals. We assessed direct scavenging activities of two water-soluble statins, fluvastatin and pravastatin, on multiple free radicals using electron spin resonance spectrometry with spin trapping method. We estimated reaction rate constants (k_fv for fluvastatin, and k_pv for pravastatin). Superoxide anion was scavenged by fluvastatin and pravastatin with k_fv and k_pv of 4.82 M⁻¹s⁻¹ and 49.0 M⁻¹s⁻¹, respectively. Scavenging effects of fluvastatin and pravastatin on hydroxyl radical were comparable; both k_fv and k_pv were >10⁹ M⁻¹s⁻¹. Fluvastatin also eliminated tert-butyl peroxyl radical with relative k_fv of 2.63 to that of CYPMPO, whereas pravastatin did not affect tert-butyl peroxyl radical. Nitric oxide was scavenged by fluvastatin and pravastatin with k_fv and k_pv of 68.6 M⁻¹s⁻¹ and 701 M⁻¹s⁻¹, respectively. Both fluvastatin and pravastatin had scavenging effects on superoxide anion, hydroxyl radical and nitric oxide radical. On the other hand, tert-butyl peroxyl radical was scavenged only by fluvastatin, suggesting that fluvastatin might have more potential effect than pravastatin to prevent atherosclerosis and ischemia/reperfusion injury via inhibiting oxidation of lipids.

Myocardial metabolism in heart failure: Purinergic signalling and other metabolic concepts

Despite significant therapeutic advances in heart failure (HF) therapy, the morbidity and mortality associated with this disease remains unacceptably high. The concept of metabolic dysfunction as an important underlying mechanism in HF is well established. Cardiac function is inextricably linked to metabolism, with dysregulation of cardiac metabolism pathways implicated in a range of cardiac complications, including HF. Modulation of cardiac metabolism has therefore become an attractive clinical target. Cardiac metabolism is based on the integration of adenosine triphosphate (ATP) production and utilization pathways. ATP itself impacts the heart not only by providing energy, but also represents a central element in the purinergic signaling pathway, which has received considerable attention in recent years. Furthermore, novel drugs that have received interest in HF include angiotensin receptor blocker-neprilysin inhibitor (ARNi) and sodium glucose cotransporter 2 (SGLT-2) inhibitors, whose favorable cardiovascular profile has been at least partly attributed to their effects on metabolism. This review, describes the major metabolic pathways and concepts of the healthy heart (including fatty acid oxidation, glycolysis, Krebs cycle, Randle cycle, and purinergic signaling) and their dysregulation in the progression to HF (including ketone and amino acid metabolism). The cardiac implications of HF comorbidities, including metabolic syndrome, diabetes mellitus and cachexia are also discussed. Finally, the impact of current HF and diabetes therapies on cardiac metabolism pathways and the relevance of this knowledge for current clinical practice is discussed. Targeting cardiac metabolism may have utility for the future treatment of patients with HF, complementing current approaches.

Cellular and molecular approaches to enhance myocardial recovery after myocardial infarction

Reperfusion therapy has resulted in significant improvement in post-myocardial infarction morbidity and mortality in over the last 4 decades. Nonetheless, it is well recognized that simply restoring patency of the epicardial artery may not stop or reverse damage at microvascular level, and myocardial salvage is often suboptimal. Numerous efforts have been undertaken to elucidate the mechanisms underlying extensive myonecrosis to facilitate the discovery of therapies to provide additional and incremental benefits over current therapeutic pathways. To date, conclusively effective strategies to promote myocardial recovery have not yet been established. Novel approaches are investigating the foundational cellular and molecular bases of myocardial ischemia and irreversible injury. Herein, we review the emerging concepts and proposed therapies that may improve myocardial protection and reduce infarct size. We examine the preclinical and clinical evidence for reduced infarct size with these strategies, including anti-inflammatory agents, intracellular ion channel modulators, agents affecting the reperfusion injury salvage kinase (RISK) and nitric oxide signaling pathways, modulators of mitochondrial function, anti-apoptotic agents, and stem cell and gene therapy. We review the potential reasons of failures to date and the potential for new strategies to further promote myocardial recovery and improve prognosis.

Gingival Periodontal Disease (PD) Level-Butyric Acid Affects the Systemic Blood and Brain Organ: Insights Into the Systemic Inflammation of Periodontal Disease

Butyric acid (BA) is produced by periodontopathic bacterial pathogens and contributes to periodontal disease (PD) induction. Moreover, PD has been associated with detrimental effects which subsequently may lead to systemic disease (SD) development affecting certain organs. Surprisingly, the potential systemic manifestations and organ-localized effects of BA have never been elucidated. Here, we simulated BA-based oral infection among young (20-week-old) rats and isolated blood cytosol to determine BA effects on stress network-related signals [total heme, hydrogen peroxide (H₂O₂), catalase (CAT), glutathione reductase (GR), free fatty acid (FFA), NADP/NADPH], inflammation-associated signals [caspases (CASP12 and CASP1), IL-1β, TNF-α, metallomatrix proteinase-9 (MMP-9), and toll-like receptor-2 (TLR2)], and neurological blood biomarkers [presenilin (PS1 and PS2) and amyloid precursor protein (APP)]. Similarly, we extracted the brain from both control and BA-treated rats, isolated the major regions (hippocampus, pineal gland, hypothalamus, cerebrum, and cerebellum), and, subsequently, measured stress network-related signals [oxidative stress: total heme, NADPH, H₂O₂, GR, and FFA; ER stress: GADD153, calcium, CASP1, and CASP3] and a brain neurodegenerative biomarker (Tau). In the blood, we found that BA was no longer detectable. Nevertheless, oxidative stress and inflammation were induced. Interestingly, amounts of representative inflammatory signals (CASP12, CASP1, IL-1β, and TNF-α) decreased while MMP-9 levels increased which we believe would suggest that inflammation was MMP-9-modulated and would serve as an alternative inflammatory mechanism. Similarly, TLR2 activity was increased which would insinuate that neurological blood biomarkers (APP, PS1, and PS2) were likewise affected. In the brain, BA was not detected, however, we found that both oxidative and ER stresses were likewise altered in all brain regions. Interestingly, tau protein amounts were significantly affected in the cerebellar and hippocampal regions which coincidentally are the major brain regions affected in several neurological disorders. Taken together, we propose that gingival BA can potentially cause systemic inflammation ascribable to prolonged systemic manifestations in the blood and localized detrimental effects within the brain organ.

High pre-ischemic fatty acid levels decrease cardiac recovery in an isolated rat heart model of donation after circulatory death

RATIONALE

Donation after circulatory death (DCD) could improve cardiac graft availability. However, strategies to optimize cardiac graft recovery remain to be established in DCD; these hearts would be expected to be exposed to high levels of circulatory fat immediately prior to the inevitable period of ischemia prior to procurement.

OBJECTIVE

We investigated whether acute exposure to high fat prior to warm, global ischemia affects subsequent hemodynamic and metabolic recovery in an isolated rat heart model of DCD.

METHODS AND RESULTS

Hearts of male Wistar rats underwent 20min baseline perfusion with glucose (11mM) and either high fat (1.2mM palmitate; HF) or no fat (NF), 27min global ischemia (37°C), and 60min reperfusion with glucose only (n=7-8 per group). Hemodynamic recovery was 50% lower in HF vs. NF hearts (34±30% vs. 78±8% (60min reperfusion value of peak systolic pressure*heart rate as percentage of mean baseline); p<0.01). During early reperfusion, glycolysis (0.3±0.3 vs. 0.7±0.3μmol*min^-1*g dry^-1, p<0.05), glucose oxidation (0.1±0.03 vs. 0.4±0.2μmol*min^-1*g dry^-1, p<0.01) and pyruvate dehydrogenase activity (1.8±0.6 vs. 3.6±0.5U*g protein^-1, p<0.01) were significantly reduced in HF vs. NF groups, respectively, while lactate release was significantly greater (1.8±0.9 vs. 0.6±0.2μmol*g wet^-1*min^-1; p<0.05).

CONCLUSIONS

Acute, pre-ischemic exposure to high fat significantly lowers post-ischemic cardiac recovery vs. no fat despite identical reperfusion conditions. These findings support the concept that oxidation of residual fatty acids is rapidly restored upon reperfusion and exacerbates ischemia-reperfusion (IR) injury. Strategies to optimize post-ischemic cardiac recovery should take pre-ischemic fat levels into consideration.

PET Radiotracers of the Cardiovascular System

Cardiovascular PET provides exquisite measurements of key aspects of the cardiovascular system and as a consequence it plays central role in cardiovascular investigation. Moreover, PET is now playing an ever increasing role in the management of the cardiac patient. Central to the success of PET is the development and use of novel radiotracers that permit measurements of key aspects of cardiovascular health such as myocardial perfusion, metabolism, and neuronal function. Moreover, the development of molecular imaging radiotracers is now permitting the interrogation of cellular and sub cellular processes. This article highlights these various radiotracers and their role in both cardiovascular research and potential clinical applications.

Inhibition of inflammation and oxidative stress by an imidazopyridine derivative X22 prevents heart injury from obesity

Inflammation and oxidative stress plays an important role in the development of obesity‐related complications and cardiovascular disease. Benzimidazole and imidazopyridine compounds are a class of compounds with a variety of activities, including anti‐inflammatory, antioxidant and anti‐cancer. X22 is an imidazopyridine derivative we synthesized and evaluated previously for anti‐inflammatory activity in lipopolysaccharide‐stimulated macrophages. However, its ability to alleviate obesity‐induced heart injury via its anti‐inflammatory actions was unclear. This study was designed to evaluate the cardioprotective effects of X22 using cell culture studies and a high‐fat diet rat model. We observed that palmitic acid treatment in cardiac‐derived H9c2 cells induced a significant increase in reactive oxygen species, inflammation, apoptosis, fibrosis and hypertrophy. All of these changes were inhibited by treatment with X22. Furthermore, oral administration of X22 suppressed high‐fat diet‐induced oxidative stress, inflammation, apoptosis, hypertrophy and fibrosis in rat heart tissues and decreased serum lipid concentration. We also found that the anti‐inflammatory and anti‐oxidative actions of X22 were associated with Nrf2 activation and nuclear factor‐kappaB (NF‐κB) inhibition, respectively, both in vitro and in vivo. The results of this study indicate that X22 may be a promising cardioprotective agent and that Nrf2 and NF‐κB may be important therapeutic targets for obesity‐related complications.

Berberine Pretreatment Confers Cardioprotection Against Ischemia-Reperfusion Injury in a Rat Model of Type 2 Diabetes

Preclinical and clinical studies have demonstrated that berberine (BBR) improves diabetic complications and reduces mortality of patients with congestive heart failure. The therapeutic effects of BBR have been reported to be mediated by its regulation of adenosine monophosphate (AMP)-activated protein kinase (AMPK). We previously reported that BBR protects against ischemia-reperfusion injury via regulating AMPK activity in both ischemic and nonischemic areas of the rat heart. Since diabetic hearts are more sensitive to ischemia-reperfusion injury, we examined whether BBR treatment exhibited cardioprotective effects in the diabetic heart. Type 2 diabetic rats were pretreated plus or minus BBR for 7 days and subjected to 30-minute ischemia followed by 120-minute reperfusion. Pretreatment of type 2 diabetic rats with BBR reduced ischemia-reperfusion injury infarct size and attenuated arrhythmia compared to untreated diabetic controls. Subsequent to ischemia-reperfusion, serum triglyceride, total cholesterol, and malondialdehyde levels were reduced by pretreatment of type 2 diabetic rats with BBR compared to untreated diabetic controls. In contrast, serum glucose and superoxide dismutase levels were unaltered. The mechanism for the BBR-mediated cardioprotective effect was examined. Pretreatment with BBR did not alter AMPK activity in ischemic areas at risk but increased AMPK activity in nonischemic areas compared to untreated diabetic controls. The increased AMPK activity in nonischemic areas was due an elevated ratio of AMP to adenosine triphosphate (ATP) and adenosine diphosphate to ATP. In addition, pretreatment with BBR increased protein kinase B (AKT) phosphorylation and reduced glycogen synthase kinase 3β (GSK3β) activity in nonischemic areas compared to untreated diabetic controls. These findings indicate that BBR protects the diabetic heart from ischemia-reperfusion injury. In addition, BBR may mediate this cardioprotective effect through AMPK activation, AKT phosphorylation, and GSK3β inhibition in the nonischemic areas of the diabetic heart.

Palmitate-induced endothelial dysfunction is attenuated by cyanidin-3-O-glucoside through modulation of Nrf2/Bach1 and NF-κB pathways

Free fatty acids (FFA), commonly elevated in diabetes and obesity, have been shown to impair endothelial functions and cause oxidative stress, inflammation, and insulin resistance. Anthocyanins represent one of the most important and interesting classes of flavonoids and seem to play a role in preventing cardiovascular diseases. Herein, we investigated the in vitro protective effects of cyanidin-3-O-glucoside (C3G) on cell signaling pathways in human umbilical vein endothelial cells (HUVECs) exposed to palmitic acid (PA), the most prevalent saturated FFA in circulation. Our data reported a significant augmentation of free radicals and oxidative stress in HUVECs exposed to PA for 3h, while C3G pretreatment improved intracellular redox status altered by FFA. Moreover, C3G significantly inhibited NF-κB proinflammatory pathway and adhesion molecules induced by PA, and these effects were attributed to the activation of Nrf2/EpRE pathway. In fact, C3G induced Nrf2 nuclear localization and activation of cellular antioxidant and cytoprotective genes at baseline and after PA exposure in endothelial cells. Our data confirm the hypothesis that natural Nrf2 inducers, such as C3G, might be a potential therapeutic strategy to protect vascular system against various stressors preventing several pathological conditions.

Inhibition of lipogenesis reduces inflammation and organ injury in sepsis

BACKGROUND

Sepsis is a life-threatening acute inflammatory condition associated with metabolic complications. Accumulation of free fatty acids (FFAs) induces inflammation and causes lipotoxic effects in the liver. Because fatty acid metabolism plays a role in the inflammatory response, we hypothesized that the administration of C75, a fatty acid synthase inhibitor, could alleviate the injury caused by sepsis.

METHODS

Male mice were subjected to sepsis by cecal ligation and puncture (CLP). At 4 h after CLP, different doses of C75 (1- or 5-mg/kg body weight) or vehicle (20% dimethyl sulfoxide in saline) were injected intraperitoneally. Blood and liver tissues were collected at 24 h after CLP.

RESULTS

C75 treatment with 1- and 5-mg/kg body weight significantly lowered FFA levels in the liver after CLP by 28% and 53%, respectively. Administration of C75 dose dependently reduced serum indexes of organ injury (aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase) and serum levels of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6). In the liver, C75 treatment reduced inflammation (TNF-α and IL-6) and oxidative stress (inducible nitric oxide synthase and cyclooxygenase 2) in a dose-dependent manner. The 5-mg dose improved the 10-d survival rate to 85% from that of 55% in the vehicle. In the presence of C75, TNF-α release in RAW 246.7 cells with 4-h lipopolysaccharide stimulation was also significantly reduced.

CONCLUSIONS

C75 effectively lowered FFA accumulation in the liver, which was associated with inhibition of inflammation and organ injury as well as improvement in survival rate after CLP. Thus, inhibition of FFA by C75 could ameliorate the hepatic dysfunction seen in sepsis.

Protective effects of extendin‑4 on hypoxia/reoxygenation‑induced injury in H9c2 cells

Glucagon-like peptide-1 (GLP-1) analogues are likely to exert cardioprotective effects via balancing the energy metabolism in cardiomyocytes following ischemic or hypoxic insults. The present study aimed to explore the protective effects and mechanism of exendin-4, a GLP-1 analogue, on cardiomyocyte glucose uptake using an in vitro model of hypoxia/reoxygenation (H/R) of H9c2 cardiomyocyte cells. Pre-treatment with exendin-4 (200 nM) prior to H/R increased the cell viability, decreased cell apoptosis, enhanced cardiomyocyte glucose uptake and increased the production of adenosine triphosphate. Exendin-4 also decreased the levels of lactate dehydrogenase and creatine kinase-MB in the culture medium. Furthermore, the activity of carnitine palmitoyltransferase-1 in the H9c2 cells was decreased, while the activity of phosphofructokinase-1 was increased following exendin-4 treatment. Moreover, pre-treatment with exendin-4 increased the expression of p38 mitogen-activated protein kinase (p38MAPK) γ and translocation of glucose transporter-1 in H9c2 cells subjected to H/R. However, these effects were attenuated by the p38MAPK inhibitors BIRB796 and SB203580. The results suggested that exendin-4 exerted significant cardioprotective effects against H/R-induced cell injury and restored the metabolic imbalance of cardiomyocytes by activating the p38MAPK signaling pathway in the H9c2 cell model. Importantly, p38MAPKγ, one subunit of p38MAPK, may have the most important function in this process. The results of the present study may be helpful in the development of novel drugs to treat patients with coronary heart disease.

Trimetazidine pretreatment inhibits myocardial apoptosis and improves cardiac function in a Swine model of coronary microembolization

OBJECTIVE

Trimetazidine (TMZ) is a well-known anti-ischemic agent; however, its efficacy and mechanism of cardioprotection on coronary microembolization (CME) are largely unknown. The present study was undertaken to determine whether TMZ pretreatment could attenuate myocardial apoptosis and improve cardiac function in a swine model of CME.

METHODS

Fifteen swine were randomly and equally divided into a sham-operated (control) group, CME group and CME plus TMZ (TMZ) group. CME was induced by injecting inert plastic microspheres (42 μm in diameter) into the left anterior descending artery. For the control group, the same dose of normal saline was substituted for the microspheres, and the TMZ group was pretreated with TMZ 30 min before microsphere injection. Cardiac function was assessed by echocardiography, myocardial apoptosis was detected by TUNEL staining, and the expression levels of cleaved caspase-9/3 were measured by Western blot 12 h after operation.

RESULTS

Compared to the control group, cardiac function in the CME group was significantly decreased (p < 0.05); however, TMZ pretreatment showed significantly improved cardiac function as compared to the CME group (p < 0.05). The myocardial apoptotic rate and the expression levels of cleaved caspase-9/3 increased remarkably in CME group as compared with the control group (p < 0.001). Again, TMZ pretreatment significantly reduced the apoptotic rate and also the expression levels of cleaved caspase-9/3 (p < 0.001).

CONCLUSION

The present study demonstrated that TMZ pretreatment could significantly inhibit CME-induced myocardial apoptosis and improve cardiac function, and that the cardioprotective effect appeared to be mediated by the blockade of the mitochondrial apoptotic pathway. These results emphasize the importance of TMZ pretreatment in the therapy of CME-induced myocardial injury.

Curcumin protects hearts from FFA-induced injury by activating Nrf2 and inactivating NF-κB both in vitro and in vivo

Obesity and increased free fatty acid (FFA) level are tightly linked, leading to the development of cardiovascular disorders. Curcumin is a natural product from Curcuma longa with multiple bioactivities and is known to have cardioprotective effects in several cellular and animal models. The current study was designed to evaluate the cardioprotective effects of curcumin and demonstrate the underlying mechanism in FFA-induced cardiac injury. Using cell culture studies and high fat in vivo model, we explored the mechanistic basis of anti-inflammatory and antioxidant activities of curcumin. We observed that palmitate (PA) treatment in cardiac derived H9C2 cells induced a marked increase in reactive oxygen species, inflammation, apoptosis and hypertrophy. All of these changes were effectively suppressed by curcumin treatment. In addition, oral administration of curcumin at 50mg/kg completely suppressed high fat diet-induced oxidative stress, inflammation, apoptosis, fibrosis, hypertrophy and tissue remodeling in mice. The beneficial actions of curcumin are closely associated with its ability to increase Nrf2 expression and inhibit NF-κB activation. Thus, both in vitro and in vivo studies showed a promising role of curcumin as a cardioprotective agent against palmitate and high fat diet mediated cardiac dysfunction. We indicated the regulatory roles of Nrf2 and NF-κB in obesity-induced heart injury, and suggested that they may be important therapeutic targets in the treatment of obesity-related disorders.

Mitochondria-mediated cardioprotection by trimetazidine in rabbit heart failure

Trimetazidine (TMZ) is used successfully for treatment of ischemic cardiomyopathy, however its therapeutic potential in heart failure (HF) remains to be established. While the cardioprotective action of TMZ has been linked to inhibition of free fatty acid oxidation (FAO) via 3-ketoacyl CoA thiolase (3-KAT), additional mechanisms have been suggested. The aim of this study was to evaluate systematically the effects of TMZ on calcium signaling and mitochondrial function in a rabbit model of non-ischemic HF and to determine the cellular mechanisms of the cardioprotective action of TMZ. TMZ protected HF ventricular myocytes from cytosolic Ca(2+) overload and subsequent hypercontracture, induced by electrical and ß-adrenergic (isoproterenol) stimulation. This effect was mediated by the ability of TMZ to protect HF myocytes against mitochondrial permeability transition pore (mPTP) opening via attenuation of reactive oxygen species (ROS) generation by the mitochondrial electron transport chain (ETC) and uncoupled mitochondrial nitric oxide synthase (mtNOS). The majority of ROS generated by the ETC in HF arose from enhanced complex II-mediated electron leak. TMZ inhibited the elevated electron leak at the level of mitochondrial ETC complex II and improved impaired activity of mitochondrial complex I, thereby restoring redox balance and mitochondrial membrane potential in HF. While TMZ decreased FAO by ~15%, the 3-KAT inhibitor 4-bromotiglic acid did not provide protection against palmitic acid-induced mPTP opening, indicating that TMZ effects were 3-KAT independent. Thus, the beneficial effect of TMZ in rabbit HF was not linked to FAO inhibition, but rather associated with reduced complex II- and uncoupled mtNOS-mediated oxidative stress and decreased propensity for mPTP opening.

Effects of fatty acids on cardioprotection by pre-ischaemic inhibition of the malate-aspartate shuttle

1. The malate-aspartate shuttle (MAS) is the main pathway for balancing extra- and intramitochondrial glucose metabolism. Pre-ischaemic shutdown of the MAS by aminooxyacetate (AOA) mimics ischaemic preconditioning (IPC) in rat glucose-perfused hearts. The aim of the present study was to determine the effects of fatty acids (FA) on cardioprotection by pre-ischaemic inhibition of the MAS. 2. Isolated rat hearts were divided into four groups (control; pre-ischaemic AOA (0.2 mmol/L); IPC; and AOA + IPC) and were perfused with 11 mmol/L glucose, 3% bovine serum albumin plus 0, 0.4 or 1.2 mmol/L FA. The perfusion protocol included 30 min global no-flow ischaemia and 120 min reperfusion. Infarct size (IS), haemodynamic recovery, glucose oxidation and lactate release were evaluated in all four groups. 3. Pre-ischaemic AOA reduced the IS of the left ventricle in hearts perfused with 0, 0.4 and 1.2 mmol/L FA compared with that in control hearts (26 ± 2% vs 53 ± 4%, 29 ± 3% vs 53 ± 4% and 61 ± 4% vs 81 ± 3%, respectively; P < 0.01 for all). After 2 h reperfusion, AOA improved haemodynamic recovery in the absence (52 ± 2 vs 27 ± 3 mmHg in the AOA and control groups, respectively; P < 0.001) but not in the presence, of FA. Both IPC and AOA + IPC reduced IS and improved haemodynamic recovery regardless of FA levels. Postischaemic glucose oxidation was suppressed by FA and did not differ significantly between the different groups. 4. In conclusion, the reduction in IS induced by pre-ischaemic MAS shutdown is not compromised by physiological FA concentrations. Transient MAS shutdown may be involved in IPC, but is not sufficient on its own as the underlying mechanism for IPC.

Rapamycin selectively alters serum chemistry in diabetic mice

The study was undertaken to explore the effect of rapamycin, an anti-inflammatory agent, on the metabolic profile of type 2 diabetic mice. Seven-month-old diabetic db/db mice and their lean littermate non-diabetic controls (db/m) were randomized to receive control chow or chow mixed with rapamycin (2.24 mg/kg/day) (each group n =20, males and females) for 4 months and sacrificed. Serum samples were analyzed for the measurement of glucose, creatinine, blood urea nitrogen (BUN), alkaline phosphatase (ALP), alanine aminotransferase (ALT), total cholesterol, total triglyceride, and total protein, using the automated dry chemistry analysis. Rapamycin elevated serum glucose in female diabetic mice. Serum creatinine tended to be higher in diabetic mice but was not affected by rapamycin; there was no difference in BUN levels among the groups. Serum ALP was elevated in diabetic mice and rapamycin lowered it only in female diabetic mice; serum ALT levels were increased in female diabetic mice, unaffected by rapamycin. Serum total protein was elevated in diabetic mice of both genders but was not affected by rapamycin. Diabetic mice from both genders had elevated serum cholesterol and triglycerides; rapamycin did not affect serum cholesterol but decreased serum total triglycerides in male diabetic mice. We conclude that rapamycin elicits complex metabolic responses in aging diabetic mice, worsening hyperglycemia in females but improving ALP in female diabetic and total triglycerides in male diabetic mice, respectively. The metabolic effects of rapamycin should be considered while performing studies with rapamycin in mice.

Antiapoptotic and antiautophagic effects of eicosapentaenoic acid in cardiac myoblasts exposed to palmitic acid

Apoptosis is a programmed cell death that plays a critical role in cell homeostasis. In particular, apoptosis in cardiomyocytes is involved in several cardiovascular diseases including heart failure. Recently autophagy has emerged as an important modulator of programmed cell death pathway. Recent evidence indicates that saturated fatty acids induce cell death through apoptosis and this effect is specific for palmitate. On the other hand, n-3 polyunsaturated fatty acids (PUFAs) have been implicated in the protection against cardiovascular diseases, cardiac ischemic damage and myocardial dysfunction. In the present study we show that n-3 PUFA eicosapentaenoic acid (EPA) treatment to culture medium of H9c2 rat cardiomyoblasts protects cells against palmitate-induced apoptosis, as well as counteracts palmitate-mediated increase of autophagy. Further investigation is required to establish whether the antiautophagic effect of EPA may be involved in its cytoprotective outcome and to explore the underlying biochemical mechanisms through which palmitate and EPA control the fate of cardiac cells.

Cardioprotection with postconditioning: loss of efficacy in murine models of type-2 and type-1 diabetes

Postconditioning (PostC), or relief of myocardial ischemia in a stuttered manner, has been shown to reduce infarct size, due in part to upregulation of survival kinase signaling. Virtually all of these data have, however, been obtained in healthy adult cohorts; the question of whether PostC-induced cardioprotection is maintained in the setting of clinically relevant comorbidities has remained largely unexplored. Accordingly, our aim was to assess the consequences of a major risk factor-diabetes-on the infarct-sparing effect of stuttered reflow. Isolated buffer-perfused hearts were obtained from normoglycemic C57BL/6J mice, BKS.Cg-m+/+Lepr(db)/J (db/db) mice (model of type-2 diabetes), C57BL/6J mice injected with streptozotocin (model of type-1 diabetes), and streptozotocin-injected mice in which normoglycemia was re-established by islet cell transplantation. All hearts underwent 30  min of ischemia and, within each cohort, hearts received either standard (control) reperfusion or three to six 10-s cycles of stuttered reflow. PostC reduced infarct size via upregulation of extracellular signal-regulated kinase 1/2 in normoglycemic mice. In contrast, diabetic hearts were refractory to PostC-induced cardioprotection-an effect that, in the type-1 model, was reversed by restoration of normoglycemia. We provide novel evidence for a profound-but potentially reversible-diabetes-induced defect in the cardioprotective efficacy of PostC.

Metabolic fingerprint of ischaemic cardioprotection: importance of the malate-aspartate shuttle

The convergence of cardioprotective intracellular signalling pathways to modulate mitochondrial function as an end-target of cytoprotective stimuli is well described. However, our understanding of whether the complementary changes in mitochondrial energy metabolism are secondary responses or inherent mechanisms of ischaemic cardioprotection remains incomplete. In the heart, the malate-aspartate shuttle (MAS) constitutes the primary metabolic pathway for transfer of reducing equivalents from the cytosol into the mitochondria for oxidation. The flux of MAS is tightly linked to the flux of the tricarboxylic acid cycle and the electron transport chain, partly by the amino acid l-glutamate. In addition, emerging evidence suggests the MAS is an important regulator of cytosolic and mitochondrial calcium homeostasis. In the isolated rat heart, inhibition of MAS during ischaemia and early reperfusion by the aminotransferase inhibitor aminooxyacetate induces infarct limitation, improves haemodynamic responses, and modulates glucose metabolism, analogous to effects observed in classical ischaemic preconditioning. On the basis of these findings, the mechanisms through which MAS preserves mitochondrial function and cell survival are reviewed. We conclude that the available evidence is supportive of a down-regulation of mitochondrial respiration during lethal ischaemia with a gradual 'wake-up' during reperfusion as a pivotal feature of ischaemic cardioprotection. Finally, comments on modulating myocardial energy metabolism by the cardioprotective amino acids glutamate and glutamine are given.

Early administration of trimetazidine may prevent or ameliorate diabetic cardiomyopathy

Diabetic cardiomyopathy is a type of cardiac dysfunction resulting from diabetes, independent of vascular or valvular pathology. It clinically manifests initially as asymptomatic diastolic dysfunction and then progresses to symptomatic heart failure. Two major contributors to the development of diabetic cardiomyopathy, which are unique to diabetes, are hyperglycemia and diabetes-related alterations in myocardial metabolism. Diabetes mellitus is characterized by reduced glucose and lactate metabolism and enhanced fatty acid metabolism, which are the early consequences of the disease. Studies on the effect of intensive glucose control on heart failure events in patients with diabetes have been conducted with neutral results. However, no study on the effect of metabolic modulators on the prevention of heart failure has been reported. Trimetazidine, a 3-ketoacyl coenzyme A thiolase (3-KAT) inhibitor, shifts cardiac energy metabolism from free fatty acid oxidation to glucose oxidation by inhibiting mitochondrial long-chain 3-KAT, and is used clinically as an effective antianginal agent. Studies have shown that trimetazidine improves heart function in patients with idiopathic cardiomyopathy and in diabetic patients with cardiac ischemia or heart failure. In addition to being effective, trimetazidine has only mild side effects. Therefore, instead of routine administration of trimetazidine for the treatment of diabetic cardiomyopathy, we hypothesize that the early application of trimetazidine may prevent or ameliorate diabetic cardiomyopathy. In addition to life style modifications, ACEI, ARB, and beta-blockers, which have been recommended in the past, trimetazidine should be administered to those patients with impaired glucose tolerance or patients in the early course of diabetes. In this way, we may reduce the prevalence of heart failure and improve the long-term survival of patients with diabetes through early normalization of the myocardial substrate metabolism.

Prolonged pain to hospital time is associated with increased plasma advanced oxidation protein products and poor prognosis in patients with percutaneous coronary intervention for ST-elevation myocardial infarction

Plasma advanced oxidation protein products (AOPP) are a biomarker for increased production of reactive oxygen species. We examined the possible association between pain to hospital time, plasma AOPP, and outcome of patients receiving percutaneous coronary intervention (PCI) for ST-elevation acute myocardial infarction (STEMI). Plasma AOPP was determined at hospitalization as well as 24 and 48 h after PCI in 79 patients with suspected STEMI. Patients were stratified into a control group (Group I, n = 21) after exclusion of coronary artery disease, Group II (n = 46) with pain to hospital time <12 h, and Group III (n = 33) with pain to hospital time >12 h. Associations between pain to hospital time and AOPP as well as incidence of major adverse cardiac events (MACE) during 6 months of follow-up were analyzed. Plasma AOPP at admission was significantly higher in patients of Group II (97.58 +/- 23.41 micromol/l) and Group III (184.52 +/- 30.41 micromol/l) in comparison with Group I (57.41 +/- 13.60 micromol/l, all P < 0.001). Plasma AOPP concentration was positively correlated with pain to hospital time and associated with an increased incidence of MACE during the 6-month follow-up period. Prolonged ischemia is associated with increased oxidative stress and poor prognosis in patients treated with PCI for STEMI.

Improvement of mechanical heart function by trimetazidine in db/db mice

AIM

To investigate the influence of trimetazidine, which is known to be an antioxidant and modulator of metabolism, on cardiac function and the development of diabetic cardiomyopathy in db/db mouse.

METHODS

Trimetazidine was administered to db/db mice for eight weeks. Cardiac function was measured by inserting a Millar catheter into the left ventricle, and oxidative stress and AMP-activated protein kinase (AMPK) activity in the myocardium were evaluated.

RESULTS

Untreated db/db mice exhibited a significant decrease in cardiac function compared to normal C57 mice. Oxidative stress and lipid deposition were markedly increased in the myocardium, concomitant with inactivation of AMPK and increased expression of peroxisome proliferator-activated receptor coactivator-1 alpha (PGC-1 alpha). Trimetazidine significantly improved systolic and diastolic function in hearts of db/db mice and led to reduced production of reactive oxygen species and deposition of fatty acid in cardiomyocytes. Trimetazidine also caused AMPK activation and reduced PGC-1 alpha expression in the hearts of db/db mice.

CONCLUSION

The data suggest that trimetazidine significantly improves cardiac function in db/db mice by attenuating lipotoxicity and improving the oxidation status of the heart. Activation of AMPK and decreased expression of PGC-1 alpha were involved in this process. Furthermore, our study suggests that trimetazidine suppresses the development of diabetic cardiomyopathy, which warrants further clinical investigation.

Trimetazidine, administered at the onset of reperfusion, ameliorates myocardial dysfunction and injury by activation of p38 mitogen-activated protein kinase and Akt signaling

Trimetazidine [1-(2,3,4-trimethoxybenzyl)piperazine; TMZ] is an anti-ischemic cardiac drug; however, its efficacy and mechanism of cardioprotection upon reperfusion are largely unknown. The objective of this study was to determine whether TMZ, given before reperfusion, could attenuate myocardial reperfusion injury. Ischemia/reperfusion (I/R) was induced in rat hearts by ligating the left anterior descending (LAD) coronary artery for 30 min followed by 48 h of reperfusion. TMZ (5 mg/kg b.wt.) was administered 5 min before reperfusion. The study used three experimental groups: control (-I/R; -TMZ), I/R (+I/R; -TMZ), and TMZ (+I/R; +TMZ). Echocardiography and EPR oximetry were used to assess cardiac function and oxygenation, respectively. The ejection fraction, which was significantly depressed in the I/R group (62 +/- 5 versus 84 +/- 3% in control), was restored to 72 +/- 3% in the TMZ group. Myocardial pO2 in the TMZ group returned to baseline levels (approximately 20 mm Hg) within 1 h of reperfusion, whereas the I/R group showed a significant hyperoxygenation even after 48 h of reperfusion. The infarct size was significantly reduced in the TMZ group (26 +/- 3 versus 47 +/- 5% in I/R). TMZ treatment significantly attenuated superoxide levels in the tissue. Tissue homogenates showed a significant increase in p38 and p-Akt and decrease in caspase-3 levels in the TMZ group. In summary, the results demonstrated that TMZ is cardioprotective when administered before reperfusion and that this protection appears to be mediated by activation of p38 mitogen-activated protein kinase and Akt signaling. The study emphasizes the importance of administering TMZ before reflow to prevent reperfusion-mediated cardiac injury and dysfunction.

Effects of hormone-sensitive lipase disruption on cardiac energy metabolism in response to fasting and refeeding

Increased fatty acid (FA) flux and intracellular lipid accumulation (steatosis) give rise to cardiac lipotoxicity in both pathological and physiological conditions. Since hormone-sensitive lipase (HSL) contributes to intracellular lipolysis in adipose tissue and heart, we investigated the impact of HSL disruption on cardiac energy metabolism in response to fasting and refeeding. HSL-knockout (KO) mice and wild-type (WT) littermates were fasted for 24 h, followed by ∼6 h of refeeding. Plasma FA concentration in WT mice was elevated twofold with fasting, whereas KO mice lacked this elevation, resulting in twofold lower cardiac FA uptake compared with WT mice. Echocardiography showed that fractional shortening was 15% decreased during fasting in WT mice and was associated with steatosis, whereas both of these changes were absent in KO mice. Compared with Langendorff-perfused hearts isolated from fasted WT mice, the isolated KO hearts also displayed higher contractile function and a blunted response to FA. Although cardiac glucose uptake in KO mice was comparable with WT mice under all conditions tested, cardiac VLDL uptake and lipoprotein lipase (LPL) activity were twofold higher in KO mice during fasting. The KO hearts showed undetectable activity of neutral cholesteryl esterase and 40% lower non-LPL triglyceride lipase activity compared with WT hearts in refed conditions accompanied by overt steatosis, normal cardiac function, and increased mRNA expression of adipose differentiation-related protein. Thus, the dissociation between cardiac steatosis and functional sequelae observed in HSL-KO mice suggests that excess FA influx, rather than steatosis per se, appears to play an important role in the pathogenesis of cardiac lipotoxicity.

Intralipid infusion diminishes return of spontaneous circulation after hypoxic cardiac arrest in rabbits

BACKGROUND

Infusion of lipid emulsion has been shown to reverse lipophilic drug-induced cardiovascular collapse in laboratory models and humans. The effect of high dose lipid in nondrug-induced cardiac arrest is, however, uncertain. In a rabbit model of asphyxial pulseless electrical activity (PEA) we compared lipid augmented with standard advanced cardiac life support (ACLS) resuscitation.

METHOD

Adult New Zealand White rabbits underwent hypoxic PEA via tracheal clamping. After 2 min of cardiac arrest, basic life support cardiopulmonary resuscitation was commenced and 3 mL/kg 20% Intralipid or 3 mL/kg 0.9% saline solution infused. Adrenaline (100 microg/kg) was administered at 4 and 5 min. Return of spontaneous circulation (ROSC), hemodynamic metrics, and survival to 50 min were recorded.

RESULTS

Seven of 11 saline-treated rabbits developed ROSC versus 1 of 12 Intralipid-treated animals; P = 0.009. No significant difference in survival to 50 min was observed (3/11 saline vs 0/12 Intralipid; P = 0.211).

CONCLUSION

In this model of hypoxia-induced PEA, standard ACLS resulted in greater coronary perfusion pressure and increased ROSC compared with ACLS plus lipid infusion. Lipid emulsion may be contraindicated in cardiac arrest complicated by significant hypoxia.

Cyclosporin A is unable to inhibit carboxyatractyloside-induced permeability transition in aged mitochondria

We studied the effect of mitochondrial ageing on membrane permeability transition. The results obtained indicate that aged mitochondria are neither able to retain Ca2+ nor to maintain a high transmembrane electric gradient. In addition, aged mitochondria undergo a large amplitude swelling. These dysfunctions were circumvented by the addition of cyclosporin A. Furthermore, it is shown that ageing-induced permeability transition causes oxidative damage on the matrix enzyme aconitase. The observed damage in aged mitochondria requires Ca2+ addition; therefore, it was not seen when Sr2+ replaced Ca2+. Two important findings in this work were the fact that despite of the presence of cyclosporin A, carboxyatractyloside was still able to induce permeability transition, and that ageing induced mitochondrial DNA disruption and release of cytochrome c. It is likely that the membrane's increased permeability is due to the effect of fatty acids, since bovine serum albumin makes mitochondria able to retain Ca2+. However, the possibility that the damage might be the result of oxidative stress cannot be discarded.

Translation of myocardial metabolic imaging concepts into the clinics

Flexibility in myocardial substrate metabolism for energy production is fundamental to cardiac health. This loss in plasticity or flexibility leads to overdependence on the metabolism of an individual category of substrates, with the predominance in fatty acid metabolism characteristic of diabetic heart disease and the accelerated glucose use associated with pressure-overload left ventricular hypertrophy being prime examples. There is a strong demand for accurate noninvasive imaging approaches of myocardial substrate metabolism that can facilitate the crosstalk between the bench and the bedside, leading to improved patient management paradigms. In this article potential future applications of metabolic imaging, particularly radionuclide approaches, for assessment of cardiovascular disease are discussed.

Pharmacological preconditioning of mesenchymal stem cells with trimetazidine (1-[2,3,4-trimethoxybenzyl]piperazine) protects hypoxic cells against oxidative stress and enhances recovery of myocardial function in infarcted heart through Bcl-2 expression

Stem cell transplantation is a possible therapeutic option to repair ischemic damage to the heart. However, it is faced with a number of challenges including the survival of the transplanted cells in the ischemic region. The present study was designed to use stem cells preconditioned with trimetazidine (1-[2,3,4-trimethoxybenzyl]piperazine; TMZ), a widely used anti-ischemic drug for treating angina in cardiac patients, to increase the rate of their survival after transplantation. Bone marrow-derived rat mesenchymal stem cells (MSCs) were subjected to a simulated host tissue environment by culturing them under hypoxia (2% O(2)) and using hydrogen peroxide (H(2)O(2)) to induce oxidative stress. MSCs were preconditioned with 10 microM TMZ for 6 h followed by treatment with 100 microM H(2)O(2) for 1 h and characterized for their cellular viability and metabolic activity. The preconditioned cells showed a significant protection against H(2)O(2)-induced loss of cellular viability, membrane damage, and oxygen metabolism accompanied by a significant increase in HIF-1alpha, survivin, phosphorylated Akt (pAkt), and Bcl-2 protein levels and Bcl-2 gene expression. The therapeutic efficacy of the TMZ-preconditioned MSCs was evaluated in an in vivo rat model of myocardial infarction induced by permanent ligation of left anterior descending coronary artery. A significant increase in the recovery of myocardial function and up-regulation of pAkt and Bcl-2 levels were observed in hearts transplanted with TMZ-preconditioned cells. This study clearly demonstrated the potential benefits of pharmacological preconditioning of MSCs with TMZ for stem cell therapy for repairing myocardial ischemic damage.

Bax signaling regulates palmitate-mediated apoptosis in C(2)C(12) myotubes

Insulin resistance is a primary characteristic of type 2 diabetes. Several lines of evidence suggest that accumulation of free fatty acids in skeletal muscle may at least in part contribute to insulin resistance and may be linked to mitochondrial dysfunction, leading to apoptosis. Palmitate treatment of several cell lines in vitro results in apoptosis and inhibits protein kinase B (Akt) activity in response to insulin. However, the role of Bax and Bcl-2 in regulating palmitate-induced apoptosis has not been well studied. Therefore, the purpose of this study was to determine whether palmitate-induced apoptosis in C(2)C(12) myotubes is dependent on Bax to Bcl-2 binding. An additional purpose of this study was to determine whether the changes in Bax to Bcl-2 binding corresponded to decreases in Akt signaling in palmitate-treated myoblasts. Apoptotic signaling proteins were examined in C(2)C(12) myotubes treated overnight with palmitate. Bax to Bcl-2 binding was determined through a coimmunoprecipitation assay that was performed in myotubes after 2 h of serum starvation, followed by 10 min of serum reintroduction. This experiment evaluated whether temporal Akt activity coincided with Bax to Bcl-2 binding. Last, the contribution of Bax to palmitate-induced apoptosis was determined by treatment with Bax siRNA. Palmitate treatment increased apoptosis in C(2)C(12) myotubes as shown by a twofold increase in DNA fragmentation, an approximately fivefold increase in caspase-3 activity, and a 2.5-fold increase in caspase-9 activity. Palmitate treatment significantly reduced Akt protein expression and Akt activity. In addition, there was a fourfold reduction in Bax to Bcl-2 binding with palmitate treatment, which mirrored the reduction in Akt(Ser473) phosphorylation. Furthermore, treatment of the C(2)C(12) myotubes with Bax siRNA attenuated the apoptotic effects of palmitate treatment. These data show that palmitate induces Bax-mediated apoptosis in C(2)C(12) myotubes and that this effect corresponds to reductions in Akt(Ser473) phosphorylation.

Trimetazidine revisited: a comprehensive review of the pharmacological effects and analytical techniques for the determination of trimetazidine

Trimetazidine (TMZ) is an effective and well-tolerated antianginal drug that possesses protective properties against ischemia-induced heart injury. Growing interest in metabolic modulation in recent years urged an up-to-date review of the literature on TMZ. This review consists of two major sections: (1) comprehensive and critical information about the pharmacological effects, mechanism of action, pharmacokinetics, side effects, and current usage of TMZ, and (2) developments in analytical techniques for the determination of the drug in raw material, pharmaceutical dosage forms, and biological samples.

Effect of trimetazidine on xanthine oxidoreductase expression in rat kidney with ischemia--reperfusion injury

Ischemia/reperfusion (I/R) injury is often responsible for delayed graft function after transplantation. Trimetazidine (TMZ) is an anti-ischemic and antioxidant agent used to protect grafts from I/R injury. With the supply of molecular oxygen upon reperfusion of ischemic tissues, xanthine oxidoreductase (XOR) metabolizes xanthine and hypoxanthine to uric acid and free radicals are generated. The aim of the study was to examine the effect of TMZ on XOR expression in rat kidney with I/R injury. The study was carried out on Wistar rats divided into two groups: animals treated with TMZ and control group receiving placebo. TMZ (10 mg/kg/day) was administered for 30 days. There were no significant differences in XOR expression in kidneys without ischemia between rats treated with TMZ and control group, whereas the XOR expression in kidneys with ischemia was significantly decreased in rats treated with TMZ as compared with control animals. The XOR expression in ischemic kidney was significantly lower in comparison with kidney without ischemia in the group treated with TMZ. We suggest that the decrease in xanthine oxidoreductase expression is one of the beneficial mechanisms of TMZ on I/R injury, preventing the degradation of purine nucleotides during the oxidation of hypoxanthine to xanthine and uric acid and formation of free radicals.

Trimetazidine inhibits cardiomyocyte apoptosis in a rabbit model of ischemia-reperfusion

The effects of trimetazidine on cardiomyocyte apoptosis and hemodynamics in a rabbit model of ischemia-reperfusion were determined. Thirty male New Zealand white rabbits were randomly divided into sham, control, and treated groups (n = 10). Trimetazidine (2 mg/kg(-1)/day(-1)) was fed for 2 weeks to treated animals before the procedure. Control and treated groups were subjected to a 30-min coronary occlusion followed by a 2-h reperfusion. Mean arterial pressure, left ventricular systolic pressure, and maximum rate of left ventricular pressure rise were significantly higher in the treated group than in the controls (P < 0.01, < 0.01, and < 0.05, respectively), whereas left ventricular end-diastolic pressure was significantly lower in the treated group than in the controls (P < 0.01). As compared with the sham group, controls had a significantly higher apoptotic index (22.10% +/- 2.85% vs 0.51% +/- 0.31%, P < 0.01) and malondialdehyde (MDA) concentration (18.52 +/- 1.51 vs 5.75 +/- 0.95 micromol/, P < 0.01), and significantly lower serum superoxide dismuase (SOD) levels (66.40 +/- 7.92 vs 89.25 +/- 1.36 microU/L, P < 0.01). Trimetazidine pretreatment apparently decreased apoptotic index (11.37% +/- 2.53%, P < 0.01 vs the sham or control) and MDA concentration (5.49 +/- 0.74 micromol/L, P > 0.05 vs sham, P < 0.01 vs control), and increased SOD levels (88.81 +/- 2.81 microU/L, P > 0.05 vs sham, P < 0.01 vs control). The caspase-3 activation and mitochondrial cytochrome c release were also higher in controls than in the treated group (P < 0.01). The apoptotic indices were negatively correlated with SOD and positively correlated with MDA in the groups, suggesting that trimetazidine may be a useful drug in preventing cardiomyocyte apoptosis and ischemia-reperfusion injury.

A novel cell-permeable antioxidant peptide, SS31, attenuates ischemic brain injury by down-regulating CD36

Oxidative stress is implicated in the pathogenesis of ischemia/reperfusion injury. Recently, we demonstrated that activation of CD36, a class B scavenger receptor, mediates free radical production and tissue injury in cerebral ischemia (1). Oxidized low density lipoproteins (oxLDL) are among the ligands that bind to CD36 and are elevated in acute cerebral infarction. SS31 is a cell-permeable antioxidant peptide that reduces intracellular free radicals and inhibits LDL oxidation/lipid peroxidation (2). The current study was designed to investigate whether treatment with SS31 normalizes ischemia-induced redox changes and attenuates CD36-mediated tissue injury. C57BL/6 mice were subjected to transient middle cerebral artery occlusion (MCAO). Redox status and infarct volume were measured in animals treated with either saline or SS31. Oxidative stress induced by ischemia/reperfusion profoundly depleted glutathione (GSH) concentrations in the ipsilateral cortex and striatum. Treating mice with SS31 immediately after reperfusion significantly attenuated ischemia-induced GSH depletion in the cortex and reduced infarct size. By contrast, the protective effect of SS31 was absent in CD36 knock-out mice, indicating that SS31 is acting through inhibition of CD36. Treating C57BL/6 mice with SS31 reduced CD36 expression in postischemic brain and mouse peritoneal macrophages (MPM). Further in vitro studies revealed that SS31 attenuated oxLDL-induced CD36 expression and foam cell formation in MPM. These in vivo and in vitro studies indicate that the down-regulation of CD36 by novel class antioxidant peptides may be a useful strategy to treat ischemic stroke victims.

Release of secondary free radicals during post-ischaemic reperfusion is not influenced by extracellular calcium levels in isolated rat hearts

In this study, we evaluated the impact of the calcium concentration present in the perfusion medium (1.2-3 mM) on contractile performance, lactate dehydrogenase (LDH) release and secondary free radical production during post-ischaemic reperfusion of isolated rat hearts. The impact of calcium concentration on post-ischaemic free radical release was investigated using the Electron Paramagnetic Resonance (EPR) technique and spin trapping with the lipophilic spin trap alpha-phenyl N-tert-butylnitrone (PBN). The evolution of left ventricular end diastolic pressure (LVEDP) in both groups followed the same pattern, but we observed that ischaemic and post-ischaemic contracture was more severe in the group of hearts perfused with 3 mM of calcium as compared with those perfused with 1.2 mM of calcium. A large release of alkyl/alkoxyl species occurred in all hearts from the onset of reperfusion and remained at a high level during the 30 min of reperfusion with no return to basal values. The kinetics and intensity of these releases were the same in both groups. In conclusion, in a range of extracellular calcium levels (1.2-3 mM), the release of alkyl/alkoxyls radicals does not seem to be calcium-dependent. Due to the protective actions of PBN itself, the results of simultaneous investigations of the effects of radical scavengers on isolated heart function may be limited. However, since many pharmacological properties (antioxidant, cellular protector, NO precursor ...) are attributed to PBN, studies investigating oxidative stress with such a multi-faceted tool make interpretation difficult.

Competition between acetate and oleate for the formation of malonyl-CoA and mitochondrial acetyl-CoA in the perfused rat heart

We previously showed that, in the perfused rat heart, the capacity of n-fatty acids to generate mitochondrial acetyl-CoA decreases as their chain length increases. In the present study, we investigated whether the oxidation of a long-chain fatty acid, oleate, is inhibited by short-chain fatty acids, acetate or propionate (which do and do not generate mitochondrial acetyl-CoA, respectively). We perfused rat hearts with buffer containing 4 mM glucose, 0.2 mM pyruvate, 1 mM lactate, and various concentrations of either (i) [U-(13)C]acetate, (ii) [U-(13)C]acetate plus [1-(13)C]oleate, or (iii) unlabeled propionate plus [1-(13)C]oleate. Using mass isotopomer analysis, we determined the contributions of the labeled substrates to the acetyl moiety of citrate (a probe of mitochondrial acetyl-CoA) and to malonyl-CoA. We found that acetate, even at low concentration, markedly inhibits the oxidation of [1-(13)C]oleate in the heart, without change in malonyl-CoA concentration. We also found that propionate, at a concentration higher than 1 mM, decreases (i) the contribution of [1-(13)C]oleate to mitochondrial acetyl-CoA and (ii) malonyl-CoA concentration. The inhibition by acetate or propionate of acetyl-CoA production from oleate probably results from a competition for mitochondrial CoA between the CoA-utilizing enzymes.