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Heart failure (HF) is a life-threatening cardiac syndrome characterized by high morbidity and mortality, but current anti-heart failure therapies have limited efficacy, necessitating the urgent development of new treatment drugs. Exogenous ketone supplementation helps prevent heart failure development in HF models, but therapeutic ketosis in failing hearts has not been systematically elucidated, limiting the use of ketones to treat HF. Here, we summarize current evidence supporting ketotherapy in HF, emphasizing ketone metabolism in the failing heart, metabolic and non-metabolic therapeutic effects, and mechanisms of ketotherapy in HF, involving the dynamics within the mitochondria. We also discuss clinical strategies for therapeutic ketosis, aiming to deepen the understanding of the characteristics of ketone metabolism, including mitochondrial involvement, and its clinical therapeutic potential in HF. [ABSTRACT FROM AUTHOR]

The article discusses the prevalence of heart failure (HF) as a major disease burden in Europe, exacerbated by comorbidities such as chronic kidney disease, anaemia, obesity, and diabetes. It highlights the systemic nature of HF, requiring an interdisciplinary approach for prevention and treatment. The new COST Action EU-METAHEART aims to address metabolic alterations in HF through research areas focusing on cardiomyocyte metabolism, coronary vascular dysfunction, immunometabolism, and mitochondrial redox alterations. The Action seeks to improve understanding, identify treatment targets, and train the next generation of scientists in this field. [Extracted from the article]

Improving energy provision in the failing heart by augmenting the creatine kinase (CK) system is a desirable therapeutic target. However, over-expression of the creatine transporter (CrT-OE) has shown that very high creatine levels result in cardiac hypertrophy and dysfunction. We hypothesise this is due to insufficient endogenous CK activity to maintain thermodynamically favourable metabolite ratios. If correct, then double transgenic mice (dTg) overexpressing both CrT and the muscle isoform of CK (CKM-OE) would rescue the adverse phenotype. In Study 1, overexpressing lines were crossed and cardiac function assessed by invasive haemodynamics and echocardiography. This demonstrated that CKM-OE was safe, but too few hearts had creatine in the toxic range. In Study 2, a novel CrT-OE line was generated with higher, homogeneous, creatine levels and phenotyped as before. Myocardial creatine was 4-fold higher in CrT-OE and dTg hearts compared to wildtype and was associated with hypertrophy and contractile dysfunction. The inability of dTg hearts to rescue this phenotype was attributed to downregulation of CK activity, as occurs in the failing heart. Nevertheless, combining both studies in a linear regression analysis suggests a modest positive effect of CKM over a range of creatine concentrations. In conclusion, we confirm that moderate elevation of creatine is well tolerated, but very high levels are detrimental. Correlation analysis lends support to the theory that this may be a consequence of limited CK activity. Future studies should focus on preventing CKM downregulation to unlock the potential synergy of augmenting both creatine and CK in the heart. [Display omitted] • Improving cardiac energetics via the creatine kinase system can be cardioprotective. • Too much creatine (>2-fold increase) causes heart failure and is not rescued by CK. • LV dysfunction causes transcriptional and post-translational down-regulation of CK. • Aim for modest increases in creatine while preventing loss of CK activity. [ABSTRACT FROM AUTHOR]

Objectives: We compared the cardioprotective capacity of Del Nido cardioplegia and warm Calafiore blood cardioplegia in an experimental setting during 90 min of ischaemia. Methods: 20 adult and 20 senescent rat hearts were isolated and mounted on a blood-perfused, pressure-controlled Langendorff apparatus. After a stabilization period, cardiac arrest (90 min) was induced by the administration of either Calafiore (Cala) or Del Nido solution (DNS). While Cala was given warm and intermittently, DNS was given as a cold single shot. During 90 min of reperfusion, cardiac function and metabolism were evaluated and biomarker levels were measured. After the end of the experiment, hearts were prepared for electronmicroscopic investigation. Results: Hearts exposed to Cala recovered faster during reperfusion compared with hearts administered DNS (Cala vs DNS at 30 min reperfusion: left ventricular developed pressure 72, SD: 22% of baseline (BL) versus 40, SD: 32% of BL, p <.001, and positive derived left ventricular pressure over time was better in both adult and senescent Cala groups (96, SD: 31% of BL) than in the DNS groups (39, SD: 27% of BL, p <.001). Ischaemic contractures were seen in the DNS groups starting after 30 min of ischaemia, whereas no rise in diastolic pressure was observed for the Cala groups. Accordingly, lactate production was higher after DNS (1.23 mg/dl (SD 0.87) than after Cala (0.33 mg/dl (SD 0.68), p =.015) at the beginning of reperfusion. Troponin I levels at the end of reperfusion were higher after DNS treatment in adult hearts (DNS: 287.9 SD: 147.7 ng/mL vs Cala 91.2: SD: 94.7 ng/mL, p =.02) and in senescent hearts (DNS: 376.5 (SD: 162.8) ng/ml versus Cala 104.7 (SD: 150.2) ng/ml, p =.025). Electron microscopy showed that the cellular oedema index was higher in adult DNS hearts (1.2 ± 0.2) than in adult Cala hearts (0.8 ± 0.1, p =.012), whereas the VS ratio was similar (0.18 ± 0.01 vs 0.17 ± 0.03). Conclusion: Calafiore cardioplegia offers better myocardial protection from ischaemia/reperfusion-related damage in isolated perfused adult and senescent rat hearts than Del Nido cardioplegia. [ABSTRACT FROM AUTHOR]

Obesity is associated with important changes in cardiac energetics and function, and an increased risk of adverse cardiovascular outcomes. Multi‐nuclear MRS and MRI techniques have the potential to provide a comprehensive non‐invasive assessment of cardiac metabolic perturbation in obesity. A rat model of obesity was created by high‐fat diet feeding. This model was characterized using in vivo hyperpolarized [1‐13C]pyruvate and [2‐13C]pyruvate MRS, echocardiography and perfused heart 31P MRS. Two groups of obese rats were subsequently treated with either caloric restriction or the glucagon‐like peptide‐1 analogue/agonist liraglutide, prior to reassessment. The model recapitulated cardiovascular consequences of human obesity, including mild left ventricular hypertrophy, and diastolic, but not systolic, dysfunction. Hyperpolarized 13C and 31P MRS demonstrated that obesity was associated with reduced myocardial pyruvate dehydrogenase flux, altered cardiac tricarboxylic acid (TCA) cycle metabolism, and impaired myocardial energetic status (lower phosphocreatine to adenosine triphosphate ratio and impaired cardiac ΔG~ATP). Both caloric restriction and liraglutide treatment were associated with normalization of metabolic changes, alongside improvement in cardiac diastolic function. In this model of obesity, hyperpolarized 13C and 31P MRS demonstrated abnormalities in cardiac metabolism at multiple levels, including myocardial substrate selection, TCA cycle, and high‐energy phosphorus metabolism. Metabolic changes were linked with impairment of diastolic function and were reversed in concert following either caloric restriction or liraglutide treatment. With hyperpolarized 13C and 31P techniques now available for human use, the findings support a role for multi‐nuclear MRS in the development of new therapies for obesity. [ABSTRACT FROM AUTHOR]

Cardiovascular disease is the leading cause of mortality worldwide. Myocardial injury resulting from ischemia can be fatal because of the limited regenerative capacity of adult myocardium. Mammalian cardiomyocytes rapidly lose their proliferative capacities, with only a small fraction of adult myocardium remaining proliferative, which is insufficient to support post‐injury recovery. Recent investigations have revealed that this decline in myocardial proliferative capacity is closely linked to perinatal metabolic shifts. Predominantly glycolytic fetal myocardial metabolism transitions towards mitochondrial fatty acid oxidation postnatally, which not only enables efficient production of ATP but also causes a dramatic reduction in cardiomyocyte proliferative capacity. Extensive research has elucidated the mechanisms behind this metabolic shift, as well as methods to modulate these metabolic pathways. Some of these methods have been successfully applied to enhance metabolic reprogramming and myocardial regeneration. This review discusses recently acquired insights into the interplay between metabolism and myocardial proliferation, emphasizing postnatal metabolic transitions. [ABSTRACT FROM AUTHOR]

Age is a prominent risk factor for cardiometabolic disease, often leading to heart structural and functional changes. However, precise molecular mechanisms underlying cardiac remodeling and dysfunction exclusively resulting from physiological aging remain elusive. Previous research demonstrated age‐related functional alterations in baboons, analogous to humans. The goal of this study is to identify early cardiac molecular alterations preceding functional adaptations, shedding light on the regulation of age‐associated changes. Unbiased transcriptomics of left ventricle samples are performed from female baboons aged 7.5–22.1 years (human equivalent ≈30–88 years). Weighted‐gene correlation network and pathway enrichment analyses are performed, with histological validation. Modules of transcripts negatively correlated with age implicated declined metabolism‐oxidative phosphorylation, tricarboxylic acid cycle, glycolysis, and fatty‐acid β‐oxidation. Transcripts positively correlated with age suggested a metabolic shift toward glucose‐dependent anabolic pathways, including hexosamine biosynthetic pathway (HBP). This shift is associated with increased glycosaminoglycan synthesis, modification, precursor synthesis via HBP, and extracellular matrix accumulation, verified histologically. Upregulated extracellular matrix‐induced signaling coincided with glycosaminoglycan accumulation, followed by cardiac hypertrophy‐related pathways. Overall, these findings revealed a transcriptional shift in metabolism favoring glycosaminoglycan accumulation through HBP before cardiac hypertrophy. Unveiling this metabolic shift provides potential targets for age‐related cardiac diseases, offering novel insights into early age‐related mechanisms. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate 18F-FDG myocardial metabolism imaging (MMI) using a total-body PET/CT scanner and explore the feasible scan duration to guide the clinical practice. Methods: A retrospective analysis was conducted on 41 patients who underwent myocardial perfusion-metabolism imaging to assess myocardial viability. The patients underwent 18F-FDG MMI with a total-body PET/CT scanner using a list-mode for 600 s. PET data were trimmed and reconstructed to simulate images of 600-s, 300-s, 120-s, 60-s, and 30-s acquisition time (G600-G30). Images among different groups were subjectively evaluated using a 5-point Likert scale. Semi-quantitative evaluation was performed using standardized uptake value (SUV), myocardial to background activity ratio (M/B), signal to noise ratio (SNR), contrast to noise ratio (CNR), contrast ratio (CR), and coefficient of variation (CV). Myocardial viability analysis included indexes of Mismatch and Scar. G600 served as the reference. Results: Subjective visual evaluation indicated a decline in the scores of image quality with shortening scan duration. All the G600, G300, and G120 images were clinically acceptable (score ≥ 3), and their image quality scores were 4.9 ± 0.3, 4.8 ± 0.4, and 4.5 ± 0.8, respectively (P > 0.05). Moreover, as the scan duration reduced, the semi-quantitative parameters M/B, SNR, CNR, and CR decreased, while SUV and CV increased, and significant difference was observed in G300-G30 groups when comparing to G600 group (P < 0.05). For myocardial viability analysis of left ventricular and coronary segments, the Mismatch and Scar values of G300-G30 groups were almost identical to G600 group (ICC: 0.968-1.0, P < 0.001). Conclusion: Sufficient image quality for clinical diagnosis could be achieved at G120 for MMI using a total-body PET/CT scanner, while the image quality of G30 was acceptable for myocardial viability analysis. [ABSTRACT FROM AUTHOR]

Background: Inadequate myocardial glucose metabolism suppression (GMS) can hamper interpretation of cardiac [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET/CT). Use of β-hydroxybutyrate (BHB) measurement before [18F]FDG injection has been proposed for predicting adequate GMS. However, limited information is available on BHB measurement in guiding preparations for [18F]FDG-PET/CT. The purpose of this study was to evaluate if point-of-care measured BHB is useful in guiding heparin premedication for cardiac [18F]FDG-PET/CT. Results: 155 patients (82 male) had followed a high-fat, low-carbohydrate diet and fasted for at least twelve hours. For the first 63 patients, BHB was measured, but it was not used to guide premedication. For the subsequent 92 patients, heparin 50 IU/kg was injected intravenously 15–20 min before [18F]FDG injection if the BHB level was low (< 0.35 mmol/l). Cardiac [18F]FDG uptake pattern was evaluated visually and [18F]FDG uptake in the myocardium and blood pool were measured. Median BHB level was 0.4 (range 0.1–5.8) mmol/l. Eighty-eight patients (57%) reached a BHB level higher than 0.35 mmol/l. 112 patients (72%) had adequate GMS. In the high BHB group, 74 patients (84%) had adequate GMS, whereas of those with low BHB, only 38 (57%) had adequate GMS (p < 0.001). In the low BHB group, the prevalence of inadequate GMS was comparable in patients with and without heparin (44% vs. 42%, p = 0.875). Conclusions: While high BHB predicts adequate GMS, unfractionated heparin does not improve GMS in patients with low BHB. [ABSTRACT FROM AUTHOR]

Aims: Reverse ventricular remodelling, defined as a decrease in left ventricular end‐systolic volume indexed to body surface area (LVESVI) or an increase in left ventricular ejection fraction (LVEF), is associated with improved clinical outcomes in patients with heart failure with reduced ejection fraction (HFrEF). However, the underlying pathophysiological mechanisms remain unclear. Methods and results: We evaluated paired core‐lab assessed echocardiograms and measurements of 92 biomarkers at baseline and 8 months thereafter in 419 participants with HFrEF. Reverse ventricular remodelling was defined as a >5% LVEF increase or >15% LVESVI relative decrease between baseline and 8 months. We evaluated the association between baseline biomarkers and their changes with reverse ventricular remodelling in the prospectively randomized controlled VICTORIA (Vericiguat Global Study in Subjects With Heart Failure With Reduced Ejection Fraction) trial. Of 419 patients (median age 66 [interquartile range 57–74] years, 27.4% women), 206 (49.2%) had reverse ventricular remodelling (either a 5% LVEF increase or a 15% LVESVI decrease). There were no differences in baseline biomarker concentrations between patients with versus those without reverse ventricular remodelling on follow‐up. However, in patients with reverse ventricular remodelling there were significant decreases in biomarkers relating to inflammation and cardiac metabolism; particularly the tumour necrosis factor superfamily member 13B (ratio 0.82, 95% confidence interval [CI] 0.77–0.88), growth differentiation factor‐15 (ratio 0.74, 95% CI 0.66–0.84), and insulin‐like growth factor binding protein 7 (ratio 0.80, 95% CI 0.73–0.88). Conclusions: Reverse ventricular remodelling in patients with HFrEF is associated with a decrease of biomarkers related to inflammation and cardiac metabolism. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to explore metabolic reprogramming in diabetic myocardium subjected to ischemia–reperfusion injury (I/RI) and potential mechanisms. Background: Increased vulnerability after I/RI in diabetic myocardium is a major cause of the high prevalence of perioperative adverse cardiac events, and the specific alterations in energy metabolism after I/RI in diabetic myocardium and the impact on increased vulnerability are not fully understood. Methods: Metabolomic methods were used to explore the differences and characteristics of metabolites in the heart tissues of four groups, and then, single‐cell RNA sequencing (ScRNA‐seq) was used to explore the potential mechanism of metabolic reprogramming. Results: It was found that the fatty acid metabolism of db/db mouse I/RI (DMI) showed a significant upward trend, especially the metabolites of ultra‐long and medium‐long‐chain fatty acids; the metabolic flow analysis found that the U‐13C glucose M + 6 was significantly higher in the C57BL mouse sham operation (NM) group than in the db/db mouse sham operation (DM) group, and in the C57BL mouse I/RI (NMI) than in the DMI group. Compared with the NMI group, the intermediate metabolites of glycolysis and tricarboxylic acid (TCA) cycle were significantly reduced in the DMI group; all comparisons were statistically significant (p < 0.05), indicating that the glucose uptake of diabetic myocardetis, the ability of glucose glycolysis after I/RI, and the contribution of glucose to TCA were significantly reduced. The results of ScRNA‐seq revealed that the number of Cluster 0 myocardial isoforms was significantly increased in diabetic myocardium, and the differential genes were mainly enriched in fatty acid metabolism, and the PPARA signaling pathway was found to be over‐activated and involved in the regulation of metabolic reprogramming of diabetic myocardial I/RI. Conclusion: Metabolic reprogramming of diabetic myocardial I/RI may be the main cause of increased myocardial vulnerability. The number of myocardial subtype Cluster 0 increased significantly, and PPARA PPARA is a ligand‐activated receptor of the nuclear hormone receptor family that plays a central regulatory role in lipid metabolism. signaling pathway activation may be a potential mechanism for reprogramming metabolism in diabetic myocardium. [ABSTRACT FROM AUTHOR]

Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like-peptide-1 (GLP-1) are incretin hormones that stimulate insulin secretion and improve glycemic control in individuals with type 2 diabetes (T2D). Data from several cardiovascular outcome trials for GLP-1 receptor (GLP-1R) agonists have demonstrated significant reductions in the occurrence of major adverse cardiovascular events in individuals with T2D. Although the cardiovascular actions attributed to GLP-1R agonism have been extensively studied, little is known regarding the cardiovascular consequences attributed to GIP receptor (GIPR) agonism. As there is now an increasing focus on the development of incretin-based co-agonist therapies that activate both the GLP-1R and GIPR, it is imperative that we understand the mechanism(s) through which these incretins impact cardiovascular function. This is especially important considering that cardiovascular disease represents the leading cause of death in individuals with T2D. With increasing evidence that perturbations in cardiac energy metabolism are a major contributor to the pathology of diabetes-related cardiovascular disease, this may represent a key component through which GLP-1R and GIPR agonism influence cardiovascular outcomes. Not only do GIP and GLP-1 increase the secretion of insulin, they may also modify glucagon secretion, both of which have potent actions on cardiac substrate utilization. Herein we will discuss the potential direct and indirect actions through which GLP-1R and GIPR agonism impact cardiac energy metabolism while interrogating the evidence to support whether such actions may account for incretin-mediated cardioprotection in T2D. [ABSTRACT FROM AUTHOR]

Na+-K+ ATPase is an integral component of cardiac sarcolemma and consists of three major subunits, namely the α-subunit with three isoforms (α1, α2, and α3), β-subunit with two isoforms (β1 and β2) and γ-subunit (phospholemman). This enzyme has been demonstrated to transport three Na and two K ions to generate a trans-membrane gradient, maintain cation homeostasis in cardiomyocytes and participate in regulating contractile force development. Na+-K+ ATPase serves as a receptor for both exogenous and endogenous cardiotonic glycosides and steroids, and a signal transducer for modifying myocardial metabolism as well as cellular survival and death. In addition, Na+-K+ ATPase is regulated by different hormones through the phosphorylation/dephosphorylation of phospholemman, which is tightly bound to this enzyme. The activity of Na+-K+ ATPase has been reported to be increased, unaltered and depressed in failing hearts depending upon the type and stage of heart failure as well as the association/disassociation of phospholemman and binding with endogenous cardiotonic steroids, namely endogenous ouabain and marinobufagenin. Increased Na+-K+ ATPase activity in association with a depressed level of intracellular Na+ in failing hearts is considered to decrease intracellular Ca2+ and serve as an adaptive mechanism for maintaining cardiac function. The slight to moderate depression of Na+-K+ ATPase by cardiac glycosides in association with an increased level of Na+ in cardiomyocytes is known to produce beneficial effects in failing hearts. On the other hand, markedly reduced Na+-K+ ATPase activity associated with an increased level of intracellular Na+ in failing hearts has been demonstrated to result in an intracellular Ca2+ overload, the occurrence of cardiac arrhythmias and depression in cardiac function during the development of heart failure. Furthermore, the status of Na+-K+ ATPase activity in heart failure is determined by changes in isoform subunits of the enzyme, the development of oxidative stress, intracellular Ca2+-overload, protease activation, the activity of inflammatory cytokines and sarcolemmal lipid composition. Evidence has been presented to show that marked alterations in myocardial cations cannot be explained exclusively on the basis of sarcolemma alterations, as other Ca2+ channels, cation transporters and exchangers may be involved in this event. A marked reduction in Na+-K+ ATPase activity due to a shift in its isoform subunits in association with intracellular Ca2+-overload, cardiac energy depletion, increased membrane permeability, Ca2+-handling abnormalities and damage to myocardial ultrastructure appear to be involved in the progression of heart failure. [ABSTRACT FROM AUTHOR]

Purpose: Myocardial infarction (MI) with subsequent inflammation is one of the most common heart conditions leading to progressive tissue damage. A reliable imaging marker to assess tissue viability after MI would help determine the risks and benefits of any intervention. In this study, we investigate whether a new mitochondria-targeted imaging agent, 18F-labeled 2'-deoxy-2'-18F-fluoro-9-β-d-arabinofuranosylguanine ([18F]F-AraG), a positron emission tomography (PET) agent developed for imaging activated T cells, is suitable for cardiac imaging and to test the myocardial viability after MI. Procedure: To test whether the myocardial [18F]-F-AraG signal is coming from cardiomyocytes or immune infiltrates, we compared cardiac signal in wild-type (WT) mice with that of T cell deficient Rag1 knockout (Rag1 KO) mice. We assessed the effect of dietary nucleotides on myocardial [18F]F-AraG uptake in normal heart by comparing [18F]F-AraG signals between mice fed with purified diet and those fed with purified diet supplemented with nucleotides. The myocardial viability was investigated in rodent model by imaging rat with [18F]F-AraG and 2-deoxy-2[18F]fluoro-D-glucose ([18F]FDG) before and after MI. All PET signals were quantified in terms of the percent injected dose per cc (%ID/cc). We also explored [18F]FDG signal variability and potential T cell infiltration into fibrotic area in the affected myocardium with H&E analysis. Results: The difference in %ID/cc for Rag1 KO and WT mice was not significant (p = ns) indicating that the [18F]F-AraG signal in the myocardium was primarily coming from cardiomyocytes. No difference in myocardial uptake was observed between [18F]F-AraG signals in mice fed with purified diet and with purified diet supplemented with nucleotides (p = ns). The [18F]FDG signals showed wider variability at different time points. Noticeable [18F]F-AraG signals were observed in the affected MI regions. There were T cells in the fibrotic area in the H&E analysis, but they did not constitute the predominant infiltrates. Conclusions: Our preliminary preclinical data show that [18F]F-AraG accumulates in cardiomyocytes indicating that it may be suitable for cardiac imaging and to evaluate the myocardial viability after MI. [ABSTRACT FROM AUTHOR]

Chronic heart failure (CHF) arises from structural and functional changes in the myocardial tissue attributable to various etiologies. Crocetin and its derivative trans‐sodium crocetinate (TSC) have exhibited cardioprotective attributes; however, their poor aqueous solubility and bioavailability impede clinical development. This study aimed to construct a cyclodextrin metal–organic frameworks (CDMOFs)‐based oral delivery system to enhance the pharmacokinetic profile and therapeutic efficacy of TSC for CHF treatment. TSC was loaded into the synthesized γ‐CDMOFs via vacuum adsorption. The CDMOFs@TSC formulation was characterized and evaluated in vitro. Pharmacokinetic and pharmacodynamic analyses were performed in beagle dogs and CHF rats induced by coronary artery ligation, respectively. Both TSC and CDMOFs@TSC elicited no discernible toxicity or pathological changes in major organs of rats, providing preliminary evidence for their biosafety. Pharmacokinetic study in beagle dogs demonstrated that CDMOFs@TSC capsules markedly increase the relative oral bioavailability by 198% versus free TSC capsules. In rats afflicted with CHF, the administration of CDMOFs@TSC yielded notable enhancements in cardiac function. Additionally, it precipitated a reduction in biomarkers linked to myocardial injury, manifested anti‐inflammatory and antifibrotic effects, and induced alterations in myocardial energy metabolism. This is the first report of CDMOFs‐based oral delivery to improve the TSC bioavailability and efficacy. The utilization of CDMOFs@TSC resulted in superior therapeutic outcomes in comparison to standalone TSC by optimizing pharmacokinetics and precise targeted delivery. These results highlight the clinical potential of CDMOF as porous carriers to enable oral delivery of natural products for CHF therapy. [ABSTRACT FROM AUTHOR]

It is still debated whether changes in metabolic flux are cause or consequence of contractile dysfunction in non-ischemic heart disease. We have previously proposed a model of cardiac metabolism grounded in a series of six moiety-conserved, interconnected cycles. In view of a recent interest to augment oxygen availability in heart failure through iron supplementation, we integrated this intervention in terms of moiety conservation. Examining published work from both human and murine models, we argue this strategy restores a mitochondrial cycle of energy transfer by enhancing mitochondrial pyruvate carrier (MPC) expression and providing pyruvate as a substrate for carboxylation and anaplerosis. Metabolomic data from failing heart muscle reveal elevated pyruvate levels with a concomitant decrease in the levels of Krebs cycle intermediates. Additionally, MPC is downregulated in the same failing hearts, as well as under hypoxic conditions. MPC expression increases upon mechanical unloading in the failing human heart, as does contractile function. We note that MPC deficiency also alters expression of enzymes involved in pyruvate carboxylation and decarboxylation, increases intermediates of biosynthetic pathways, and eventually leads to cardiac hypertrophy and dilated cardiomyopathy. Collectively, we propose that an unbroken chain of moiety-conserved cycles facilitates energy transfer in the heart. We refer to the transport and subsequent carboxylation of pyruvate in the mitochondrial matrix as an example and a proposed target for metabolic support to reverse impaired contractile function. [Display omitted] • Metabolic cycles in the heart optimize transfer of available energy • Energy transfer is impaired in heart failure • Moiety-conserved cycles are a potential target in the treatment of heart failure [ABSTRACT FROM AUTHOR]

Nicotinamide adenine dinucleotide provides the critical redox pair, NAD+ and NADH, for cellular energy metabolism. In addition, NAD+ is the precursor for de novo NADP+ synthesis as well as the co-substrates for CD38, poly(ADP-ribose) polymerase and sirtuins, thus, playing a central role in the regulation of oxidative stress and cell signaling. Declines of the NAD+ level and altered NAD+/NADH redox states have been observed in cardiometabolic diseases of various etiologies. NAD based therapies have emerged as a promising strategy to treat cardiovascular disease. Strategies that reduce NAD+ consumption or promote NAD+ production have repleted intracellular NAD+ or normalized NAD+/NADH redox in preclinical studies. These interventions have shown cardioprotective effects in multiple models suggesting a great promise of the NAD+ elevating therapy. Mechanisms for the benefit of boosting NAD+ level, however, remain incompletely understood. Moreover, despite the robust pre-clinical studies there are still challenges to translate the therapy to clinic. Here, we review the most up to date literature on mechanisms underlying the NAD+ elevating interventions and discuss the progress of human studies. We also aim to provide a better understanding of how NAD metabolism is changed in failing hearts with a particular emphasis on types of strategies employed and methods to target these pathways. Finally, we conclude with a comprehensive assessment of the challenges in developing NAD-based therapies for heart diseases, and to provide a perspective on the future of the targeting strategies. • Intracellular NAD+ level and NAD+/NADH ratio are critical regulators of cell signaling, oxidative stress and metabolic flux. • Boosting NAD+ levels has shown benefit in preclinical studies of heart failure but mechanisms are incompletely understood. • Reliable biomarkers of tissue NAD(H) levels in patients will facilitate the translation of the therapy to the clinic. [ABSTRACT FROM AUTHOR]

Myocardial Infarction (MI) is a leading cause of death worldwide. Metabolic modulation is a promising therapeutic approach to prevent adverse remodeling after MI. However, whether material‐derived cues can treat MI through metabolic regulation is mainly unexplored. Herein, a Cu2+ loaded casein microgel (CuCMG) aiming to rescue the pathological intramyocardial metabolism for MI amelioration is developed. Cu2+ is an important ion factor involved in metabolic pathways, and intracardiac copper drain is observed after MI. It is thus speculated that intramyocardial supplementation of Cu2+ can rescue myocardial metabolism. Casein, a milk‐derived protein, is screened out as Cu2+ carrier through molecular‐docking based on Cu2+ loading capacity and accessibility. CuCMGs notably attenuate MI‐induced cardiac dysfunction and maladaptive remodeling, accompanied by increased angiogenesis. The results from unbiased transcriptome profiling and oxidative phosphorylation analyses support the hypothesis that CuCMG prominently rescued the metabolic homeostasis of myocardium after MI. These findings enhance the understanding of the design and application of metabolic‐modulating biomaterials for ischemic cardiomyopathy therapy. [ABSTRACT FROM AUTHOR]

Heart failure with preserved ejection fraction (HFpEF) has recently emerged as an insidiously and increasingly prevalent heart failure phenotype. HFpEF often occurs in the context of hypertension and obesity and presents with diastolic dysfunction, ventricular hypertrophy, and myocardial fibrosis. Despite growing study of HFpEF, the causal links between early metabolic changes, bioenergetic perturbations, and cardiac structural remodeling remain unclear. This study sought to elucidate the contribution of the respective pathophysiological drivers of the HFpEF symptom suite using a recently developed two‐hit mouse model. By studying the independent and concomitant consequences of hypertension and obesity‐driven metabolic dysfunction on cardiac structure and function, we revealed the causative drivers of cardiac functional, structural, and metabolic remodeling in male HFpEF mice. We found that hypertensive male mice developed diastolic dysfunction and cardiac hypertrophy regardless of obesity status and that obese mice exhibited altered systemic glucose metabolism and increased cardiac mitochondrial fatty‐acid metabolism independent of hypertension status. Taken together, our results suggest that the cardiac structural and metabolic HFpEF symptoms in this two‐hit model occur as direct results of each of the two "hits." The results of this study help to clarify the pathogenic HFpEF cascade, providing causal insights that may aid in the development of more precisely targeted therapeutics. [ABSTRACT FROM AUTHOR]

Background: Cardiac lipid metabolism reprogramming is recognized as a critical pathological factor in the progression of chronic heart failure (CHF). The therapeutic potential of digilanid C and electroacupuncture stimulation (ES) in enhancing lipid metabolism and cardiac function has been established. However, the optimal synergistic regulatory strategies of these interventions on cardiac lipid metabolism have yet to be elucidated. Methods: This study aimed to comprehensively evaluate the impact of a digilanid C-ES combination on cardiac steatosis remodeling in CHF. Assessments were conducted across various dimensions, including myocardial oxygen consumption, mitochondrial function, and lipid metabolism. Additionally, we sought to uncover the underlying neuromolecular mechanisms. Results: Our findings, at both molecular and morphological levels, indicated that the synergistic application of digilanid C and ES significantly inhibited myocardial fibrosis and steatosis. This combination therapy facilitated the repair of cardiac neuro-vascular uncoupling and induced a reprogramming of lipid metabolism. Notably, the digilanid C-ES combination ameliorated cardiomyocyte apoptosis and enhanced mitochondrial biogenesis in CHF, leading to a restructured energy supply pattern. Cardiac immunofluorescence analyses revealed the aggregation of cardiac glial cells (CGCs) at sites of abnormal neurovascular coupling, a response to cardiac lipid degeneration. This was accompanied by a marked reduction in the abnormally elevated expression of interleukin 6 (IL-6) and glutamatergic signaling, which correlated with the severity of cardiac steatosis and the aberrant activation of CGCs. The combined therapy was found to activate the Janus kinase 1 (JAK1)/signal transducer and activator of transcription 3 (STAT3) pathway, effectively attenuated lipid accumulation and overrecruitment of CGCs and deprivation of glutamatergic nerves. Conclusion: These findings underscore the potential of digilanid C and ES combination therapy as a novel approach to modulate the complex interplay between neurovascular dynamics and metabolic dysregulation in CHF. [ABSTRACT FROM AUTHOR]

Constricting pythons, known for their ability to consume infrequent, massive meals, exhibit rapid and reversible cardiac hypertrophy following feeding. Our primary goal was to investigate how python hearts achieve this adaptive response after feeding. Isolated myofibrils increased force after feeding without changes in sarcomere ultrastructure and without increasing energy cost. Ca2+ transients were prolonged after feeding with no changes in myofibril Ca2+ sensitivity. Feeding reduced titin-based tension, resulting in decreased cardiac tissue stiffness. Feeding also reduced the activity of sirtuins, a metabolically linked class of histone deacetylases, and increased chromatin accessibility. Transcription factor enrichment analysis on transposase-accessible chromatin with sequencing revealed the prominent role of transcription factors Yin Yang1 and NRF1 in postfeeding cardiac adaptation. Gene expression also changed with the enrichment of translation and metabolism. Finally, metabolomics analysis and adenosine triphosphate production demonstrated that cardiac adaptation after feeding not only increased energy demand but also energy production. These findings have broad implications for our understanding of cardiac adaptation across species and hold promise for the development of innovative approaches to address cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Aims: Heart failure (HF) is associated with profound changes in cardiac metabolism. At present, there is still a lack of relevant research to explore the key microbiome and their metabolites affecting the progression of HF. Herein, the interaction of gut microbiota and circulating free fatty acid (FFA) in HF patients and mice is investigated. Methods and Results: In HF patients, by applying metagenomics analysis and targeted FFA metabolomics, enriched abundance of Clostridium sporogenes (C.sp) in early and late stage of HF patients, which negatively correlated to saturated free fatty acid (SFA) levels, is identified. KEGG analysis further indicates microbiota gene enrichment in FFA degradation in early HF, and decreased gene expression in FFA synthesis in late HF. In HF mice (C57BL/6J) induced by isoproterenol (ISO), impaired intestinal permeability is observed, and decreased fecal C.sp and increased SFA are further validated. At last, by supplementing C.sp to ISO‐induced HF mice, the cardiac function, fibrosis, and myocardial size are partially rescued, together with decreased circulating SFA levels. Conclusions: Clostridium abundance is increased in HF, compensating cardiac function deterioration via downregulation of circulating SFA levels. The results demonstrate that the gut microbiota–SFA axis plays an important role in HF protection, which may provide a strategic advantage for the probiotic therapy development in HF. [ABSTRACT FROM AUTHOR]

Surgical revascularization is the gold standard in the management of patients with multi-vessel coronary artery disease (CAD). It is well known that increased oxidative stress during ischemia-reperfusion and post-revascularization procedures leads to the release of free radical in the circulation. This process can cause reversible or irreversible myocardial damage. The aim of this study was to assess the effect of trimetazidine on decreasing postoperative ischemia-reperfusion myocardial damage. This prospective single-blind randomized controlled trial included 90 patients with elective surgery, operated between March 2018 and October 2018. The patients were divided into two equal groups, a study group and a control group; those in the study group received trimetazidine 35 mg b.d., immediately after tracheal extubation, in addition to their regular therapy. Pre- and postoperative levels of specific blood biomarkers such as high-sensitivity troponin T (hs-TnT), creatine kinase-MB (CK-MB), and malondialdehyde (MDA) were evaluated. Patients were followed for a period of 6 months after surgery. MDA levels were lower in patients who received trimetazidine, leading to a reduction in oxidative stress and improved cardiomyocyte protection by augmentation of the antioxidant status. The quality-of-life assessment with the Minnesota Living with Heart Failure Questionnaire yielded excellent results. Improvement of myocardial cell metabolism and decreasing the level of postoperative ischemiareperfusion damage is alleviated by postoperative regular trimetazidine therapy. [ABSTRACT FROM AUTHOR]

Cardiac metabolism ensures a continuous ATP supply, primarily using fatty acids in a healthy state and favoring glucose in pathological conditions. Pyruvate kinase muscle (PKM) controls the final step of glycolysis, with PKM1 being the main isoform in the heart. PKM2, elevated in various heart diseases, has been suggested to play a protective role in cardiac stress, but its function in basal cardiac metabolism remains unclear. We examined hearts from global PKM2 knockout (PKM2−/−) mice and found reduced intracellular glucose. Isotopic tracing of U‐13C glucose revealed a shift to biosynthetic pathways in PKM2−/− cardiomyocytes. Total ATP content was two‐thirds lower in PKM2−/− hearts, and functional analysis indicated reduced mitochondrial oxygen consumption. Total reactive oxygen species (ROS) and mitochondrial superoxide were also increased in PKM2−/− cardiomyocytes. Intriguingly, PKM2−/− hearts had preserved ejection fraction compared to controls. Mechanistically, increased calcium/calmodulin‐dependent kinase II activity and phospholamban phosphorylation may contribute to higher sarcoendoplasmic reticulum calcium ATPase 2 pump activity in PKM2−/− hearts. Loss of PKM2 led to altered glucose metabolism, diminished mitochondrial function, and increased ROS in cardiomyocytes. These data suggest that cardiac PKM2 acts as an important rheostat to maintain ATP levels while limiting oxidative stress. Although loss of PKM2 did not impair baseline contractility, its absence may make hearts more sensitive to environmental stress or injury. [ABSTRACT FROM AUTHOR]

Acute myocardial infarction (MI) is a sudden, severe cardiac ischemic event that results in the death of up to one billion cardiomyocytes (CMs) and subsequent decrease in cardiac function. Engineered cardiac tissues (ECTs) are a promising approach to deliver the necessary mass of CMs to remuscularize the heart. However, the hypoxic environment of the heart post-MI presents a critical challenge for CM engraftment. Here, we present a high-throughput, systematic study targeting several physiological features of human induced pluripotent stem cell-derived CMs (hiPSC-CMs), including metabolism, Wnt signaling, substrate, heat shock, apoptosis, and mitochondrial stabilization, to assess their efficacy in promoting ischemia resistance in hiPSC-CMs. The results of 2D experiments identify hypoxia preconditioning (HPC) and metabolic conditioning as having a significant influence on hiPSC-CM function in normoxia and hypoxia. Within 3D engineered cardiac tissues (ECTs), metabolic conditioning with maturation media (MM), featuring high fatty acid and calcium concentration, results in a 1.5-fold increase in active stress generation as compared to RPMI/B27 control ECTs in normoxic conditions. Yet, this functional improvement is lost after hypoxia treatment. Interestingly, HPC can partially rescue the function of MM-treated ECTs after hypoxia. Our systematic and iterative approach provides a strong foundation for assessing and leveraging in vitro culture conditions to enhance the hypoxia resistance, and thus the successful clinical translation, of hiPSC-CMs in cardiac regenerative therapies. [ABSTRACT FROM AUTHOR]

Aims: The aims of our study were to evaluate whether point‐of‐care β‐hydroxybutyrate (BHB) measurement can be used to identify patients with adequate cardiac glucose metabolism suppression for cardiac [18F]‐fluoro‐2‐deoxy‐d‐glucose‐positron emission tomography with computerized tomography (FDG‐PET/CT) and to develop a pretest probability calculator of myocardial suppression using other metabolic factors attainable before imaging. Methods and Results: We recruited 193 patients with any clinical indication for whole body [18F]‐FDG‐PET/CT. BHB level was measured with a point‐of‐care device. Maximal myocardial standardized uptake value using lean body mass (SULmax) was measured from eight circular regions of interest with 1 cm circumference and background from left ventricular blood pool. Correlations SULmax and point‐of‐care measured BHB were analysed. The ability of BHB test to predict adequate suppression was evaluated with receiver operating characteristic analysis. Liver and spleen attenuation in computed tomography were measured to assess the presence of fatty liver. BHB level correlated with myocardial uptake and, using a cut‐off value of 0.35 mmol/L to predict adequate myocardial suppression, we reached specificity of 90% and sensitivity of 56%. Other variables to predict adequate suppression were diabetes, obesity, ketogenic diet and fatty liver. Using information attainable before imaging, we created a pretest probability calculator of inadequate myocardial glucose metabolism suppression. The area under the curve for BHB test alone was 0.802 and was 0.857 for the pretest calculator (p = 0.319). Conclusions: BHB level measured with a point‐of‐care device is useful in predicting adequate myocardial glucose metabolism suppression. More detailed assessment of other factors potentially contributing to cardiac metabolism is needed. [ABSTRACT FROM AUTHOR]

Understanding of the mechanisms contributing to the increased maternal susceptibility for major adverse cardiovascular events in the postpartum period remains poor. Accordingly, this study tested the hypothesis that the balance between coronary blood flow and myocardial metabolism is compromised during the puerperium period (35–45 days post-delivery) in swine. Systemic and coronary hemodynamic responses were assessed in anesthetized, open-chest control (nonpregnant) and puerperium/postpartum swine at baseline and in response to intravenous infusion of dobutamine (1–30 μg/kg/min). Blood pressure and heart rate were lower in postpartum swine at baseline and in response to dobutamine (P < 0.05). Coronary blood flow and myocardial oxygen delivery were significantly diminished at baseline in postpartum swine (P < 0.001), which corresponded with ∼35% reduction in myocardial oxygen consumption (MVO 2) (P < 0.001). Postpartum swine displayed enhanced retrograde coronary flow, larger cardiomyocyte area (P < 0.01) and marked capillary rarefaction (P < 0.01). The relationship between coronary blood flow and heart rate (P < 0.05) or MVO 2 (P < 0.001) was significantly diminished in postpartum swine as dobutamine increased MVO 2 up to ∼135% in both groups. This reduction in myocardial perfusion was associated with decreases in myocardial lactate uptake (P < 0.001), increases in coronary venous PCO 2 (P < 0.01) and decreased coronary venous pH (P < 0.01). These findings suggest an impaired balance between coronary blood flow and myocardial metabolism could contribute to the increased incidence of maternal myocardial ischemia and premature death in the postpartum period. [Display omitted] • Alterations in the structure and function of the coronary circulation characterize postpartum changes to the maternal heart. • Resting coronary flow is diminished in the maternal heart in the postpartum condition. • Indices of under-perfusion are present in maternal swine hearts in the postpartum condition. • Mechanisms contributing to dysregulated coronary control in the postpartum maternal heart require further investigation. [ABSTRACT FROM AUTHOR]

Aims: To investigate how a change in body position with light‐intensity physical activity (PA) 'snacks' (LIPAS, alternate sitting and standing, walking or standing continuously) compared with uninterrupted prolonged sitting affects glucose metabolism and heart rate variability (HRV) parameters in young adults with overweight and obesity. Materials and Methods: We conducted a four‐arm randomized controlled crossover trial. The following conditions were tested during an 8‐h simulated workday: uninterrupted prolonged sitting (SIT), alternate sitting and standing (SIT‐STAND; 2.5 h total), continuous standing (STAND), and continuous walking (1.0 mph; WALK). The primary outcome was to investigate how a change in body position (alternate sitting and standing, walking or standing continuously) compared with uninterrupted sitting affects mean 8‐h glucose metabolism. Secondary outcomes included the effects on 2‐h postprandial glucose concentrations, as well as on 8‐h/24‐h heart rate and HRV parameters, in the respective study arms. Capillary blood samples were drawn from an hyperemised earlobe in the fasted state and once every hour during each trial intervention by puncturing the earlobe with a lancet and collecting 20 μL of blood (Biosen S‐Line Lab+; EKF diagnostics, Barleben, Germany). HRV was assessed for 24 h including the 8‐h intervention phase, and a home phase by means of a Holter electrocardiogram. All participants received the same standardized non‐relativised breakfast and lunch during the four trial visits. Results: Seventeen individuals (eight women, mean age 23.4 ± 3.3 years, body mass index 29.7 ± 3.8 kg/m2, glycated haemoglobin level 34.8 ± 3.1 mmol/mol [5.4 ± 0.3%], body fat 31.8 ± 8.2%) completed all four trial arms. Compared with SIT (89.4 ± 6.8 mg/dL), 8‐h mean glucose was lower in all other conditions (p < 0.05) and this was statistically significant compared with WALK (86.3 ± 5.2 mg/dL; p = 0.034). Two‐hour postprandial glucose after breakfast was approximately 7% lower for WALK compared with SIT (p = 0.002). Furthermore, significant time × condition effects on HRV parameters favouring light‐intensity walking were observed (p < 0.001). Conclusions: Replacement and interruption of prolonged sitting with light‐intensity walking showed a significant blood glucose‐lowering effect and improved HRV during an 8‐h work environment in young adults with overweight and obesity. [ABSTRACT FROM AUTHOR]

The article argues for elevating the standards in cardiovascular secondary prevention, with reference to a study which explored the association of treatment with sodium-glucose cotransporter-2 inhibitors and reduced risk of atrial fibrillation occurrence after catheter ablation in patients with type 2 diabetes mellitus.

Oxidative phosphorylation is regulated by mitochondrial calcium (Ca2+) in health and disease. In physiological states, Ca2+ enters via the mitochondrial Ca2+ uniporter and rapidly enhances NADH and ATP production. However, maintaining Ca2+ homeostasis is critical: insufficient Ca2+ impairs stress adaptation, and Ca2+ overload can trigger cell death. In this review, we delve into recent insights further defining the relationship between mitochondrial Ca2+ dynamics and oxidative phosphorylation. Our focus is on how such regulation affects cardiac function in health and disease, including heart failure, ischemia-reperfusion, arrhythmias, catecholaminergic polymorphic ventricular tachycardia, mitochondrial cardiomyopathies, Barth syndrome, and Friedreich's ataxia. Several themes emerge from recent data. First, mitochondrial Ca2+ regulation is critical for fuel substrate selection, metabolite import, and matching of ATP supply to demand. Second, mitochondrial Ca2+ regulates both the production and response to reactive oxygen species (ROS), and the balance between its pro- and antioxidant effects is key to how it contributes to physiological and pathological states. Third, Ca2+ exerts localized effects on the electron transport chain (ETC), not through traditional allosteric mechanisms but rather indirectly. These effects hinge on specific transporters, such as the uniporter or the Na+/Ca2+ exchanger, and may not be noticeable acutely, contributing differently to phenotypes depending on whether Ca2+ transporters are acutely or chronically modified. Perturbations in these novel relationships during disease states may either serve as compensatory mechanisms or exacerbate impairments in oxidative phosphorylation. Consequently, targeting mitochondrial Ca2+ holds promise as a therapeutic strategy for a variety of cardiac diseases characterized by contractile failure or arrhythmias. [ABSTRACT FROM AUTHOR]

This article discusses the relationship between cardiac energy metabolism and cardiac function in obesity and type 2 diabetes. It highlights the advancements in studying cardiac energy metabolism, including the use of imaging techniques and the discovery of fatty acids as the primary fuel source for the heart. The article revisits a classic study by Aasum et al. that examined how obesity and type 2 diabetes affect cardiac energy metabolism. The study found that alterations in cardiac energy metabolism can directly lead to cardiac dysfunction. These findings have had a significant impact on our understanding of cardiac energy metabolism in obesity and type 2 diabetes. The article also discusses potential targets for pharmacotherapy to alleviate cardiovascular disease associated with obesity and type 2 diabetes. Future research in this field aims to explore the molecular mechanisms underlying these metabolic alterations and their effects on cardiac function. [Extracted from the article]

Beta-blockers are first-line drugs in the treatment of chronic heart failure (CHF). However, there is no consensus on the specific effects of the beta-blockers of the I-III generation on energy metabolism in CHF. The aim of this study is to conduct a study of beta-blockers of different generations on myocardial energy metabolism in experimental CHF. CHF was modeled in white outbred rats by administering doxorubicin. The study drugs were administered intragastrically—new drug Hypertril (1-(β-phenylethyl)-4-amino-1,2,4-triazolium bromide)-3.5 mg/kg, Metoprolol—15 mg/kg, Nebivolol −10 mg/kg, Carvedilol 50 mg/kg, and Bisoprolol, 10 mg/kg. In the myocardium, the main indices of energy metabolism were determined—ATP, ADP, AMP, malate, lactate, pyruvate, succinate dehydrogenase (SDH) activity, and NAD-dependent malate dehydrogenase (NAD-MDH) activity. Traditional second-generation beta-blockers (Metoprolol and Bisoprolol) did not affect the studied indices of energy metabolism, and third-generation beta-blockers with additional properties—Carvedilol and, especially, Nebivalol and Hypertril—improved myocardial energy metabolism. The obtained results will help to expand our understanding of the effect of beta-blockers of various generations used to treat cardiovascular diseases on energy metabolism, and are also an experimental justification for the practical choice of these drugs in the complex therapy of CHF. [ABSTRACT FROM AUTHOR]

The clinical usage of doxorubicin (DOX) is hampered due to cardiomyopathy. Studies reveal that estrogen (E2) modulates DOX-induced cardiotoxicity. Yet, the exact mechanism is unclear. The objective of the current study is to evaluate the influence of E2 and more specifically its metabolite 2-methoxyestradiol (2ME) on cardiac remodeling and the reprogramming of cardiac metabolism in rats subjected to DOX cardiotoxicity. Seventy-two female rats were divided into groups. Cardiotoxicity was induced by administering DOX (2.5 mg/kg three times weekly for 2 weeks). In some groups, the effect of endogenous E2 was abolished by ovariectomy (OVX) or by using the estrogen receptor (ER) blocker Fulvestrant (FULV). The effect of administering exogenous E2 or 2ME in the OVX group was studied. Furthermore, the influence of entacapone (COMT inhibitor) on induced cardiotoxicity was investigated. The evaluated cardiac parameters included ECG, histopathology, cardiac-related enzymes (creatine kinase isoenzyme-MB (CK-MB) and lactate dehydrogenase (LDH)), and lipid profile markers (total cholesterol (TC), triglyceride (TG), and high-density lipoprotein (HDL)). The expression levels of key metabolic enzymes (glucose transporter-4 (GLUT4) and carnitine palmitoyltransferase-1B (CPT-1B)) were assessed. Our results displayed that co-treatment of E2 and/or 2ME with DOX significantly reduced DOX-induced cardiomyopathy and enhanced the metabolism of the heart through the maintenance of GLUT4 and CPT-1B enzymes. On the other hand, co-treatment of DOX with OVX, entacapone, or FULV increased the toxic effect of DOX by further reducing these important metabolic enzymes. E2 and 2ME abrogate DOX-induced cardiomyopathy partly through modulation of GLUT 4 and CPT-1B enzymes. [ABSTRACT FROM AUTHOR]

Myocardial perfusion imaging (MPI) with single photon emission computed tomography is an established non-invasive technique for assessing myocardial ischemia. This method involves the intravenous administration of a radiopharmaceutical that accumulates in the heart muscle proportional to regional blood flow. However, image quality and diagnostic accuracy can be compromised by various technical and patient-related factors, including high non-specific radiopharmaceutical uptake in abdominal organs such as the stomach, intestines, liver, and gall-bladder, leading to subdiaphragmatic artifacts. These artifacts are particularly problematic for evaluating inferior wall perfusion and often necessitate repeated imaging, which decreases gamma camera availability and prolongs imaging times. Despite numerous investigated techniques to reduce interfering gastrointestinal activity, results have been inconsistent, and current MPI guidelines provide scant information on effective procedures to mitigate this issue. Based on our experience, some possible approaches to reducing artifacts include choosing stress testing with an exercise stress test, when possible, late imaging, fluid intake, and consuming carbonated water immediately before imaging. [ABSTRACT FROM AUTHOR]

Background and Purpose: Adenosine receptor activation induces delayed, sustained cardioprotection against ischaemia–reperfusion (IR) injury (24–72 h), but the mechanisms underlying extended cardioprotection duration remain unresolved. We hypothesized that a positive feedback loop involving adenosine receptor‐induced proteasomal degradation of adenosine kinase (ADK) and decreased myocardial adenosine metabolism extends the duration of cardioprotection. Experimental Approach: Mice were administered an ADK inhibitor, ABT‐702, to induce endogenous adenosine signalling. Cardiac ADK protein and mRNA levels were analysed 24–120 h later. Theophylline or bortezomib was administered 24 h after ABT‐702 to examine the late roles of adenosine receptors or proteasomal activity, respectively, in ADK expression and cardioprotection at 72 h. Coronary flow and IR tolerance were analysed by Langendorff technique. The potential for continuous adenosinergic cardioprotection was examined using heterozygous, cardiac‐specific ADK KO (cADK+/−) mice. Cardiac ADK expression was also examined after A1 or A3 receptor agonist, phenylephrine, lipopolysaccharide or sildenafil administration. Key results: ABT‐702 treatment decreased ADK protein content and provided cardioprotection from 24 to 72 h. ADK mRNA upregulation restored ADK protein after 96–120 h. Adenosine receptor or proteasome inhibition at 24 h reversed ABT‐702‐induced ADK protein deficit and cardioprotection at 72 h. cADK+/− hearts exhibited continuous cardioprotection. Diverse preconditioning agents also diminished cardiac ADK protein expression. Conclusion and Implications: A positive feedback loop driven by adenosine receptor‐induced ADK degradation and renewed adenosine signalling extends the duration of cardioprotection by ABT‐702 and possibly other preconditioning agents. The therapeutic potential of continuous adenosinergic cardioprotection is demonstrated in cADK+/− hearts. [ABSTRACT FROM AUTHOR]

The adult mammalian heart has been demonstrated to be endowed with low but real turnover capacity, especially for cardiomyocytes, the key functional cell type. The source, however, of that turnover capacity remains controversial. In this regard, we have defined and characterized a resident multipotent cardiac mouse progenitor population, Bmi1+DR (for Bmi1+ Damage-Responsive cells). Bmi1+DR is one of the cell types with the lowest ROS (Reactive Oxygen Species) levels in the adult heart, being particularly characterized by their close relationship with cardiac vessels, most probably involved in the regulation of proliferation/maintenance of Bmi1+DR. This was proposed to work as their endothelial niche. Due to the scarcity of Bmi1+DR cells in the adult mouse heart, we have generated an immortalization/dis-immortalization model using Simian Vacuolating Virus 40-Large Antigen T (SV40-T) to facilitate their in vitro characterization. We have obtained a heterogeneous population of immortalized Bmi1+DR cells (Bmi1+DRIMM) that was validated attending to different criteria, also showing a comparable sensitivity to strong oxidative damage. Then, we concluded that the Bmi1-DRIMM population is an appropriate model for primary Bmi1+DR in vitro studies. The co-culture of Bmi1+DRIMM cells with endothelial cells protects them against oxidative damage, showing a moderate depletion in non-canonical autophagy and also contributing with a modest metabolic regulation. [ABSTRACT FROM AUTHOR]

Purpose: Cardiac 2-deoxy-2-[F-18]fluoro-D-glucose positron emission tomography (FDG PET) is widely used to assess myocardial viability in patients with ischemic heart disease. While sufficient glucose uptake is a prerequisite for accurate interpretation of cardiac viability, there are a lack of data on which clinical variables have the most significant impact on myocardial glucose metabolism. Therefore, this study was designed to evaluate several clinical variables that could affect myocardial glucose metabolism. Methods: A total of 214 consecutive cases were retrospectively enrolled in this study. All subjects received 250 mg of acipimox and underwent glucose loading as preparation for cardiac FDG PET/CT. Three-dimensional regions of interest (ROIs) were drawn on PET/CT fusion images. Myocardial glucose uptake ratio (MGUR = SUVmax of LV myocardium/SUVmean of liver) was then calculated. Multiple clinical variables including body mass index (BMI), blood glucose levels at different times, administered insulin dosage, lipid profiles, and ejection fraction were measured and analyzed for correlation with myocardial glucose uptake. After dichotomizing the subjects based on a BMI of 25, each group's MGUR was compared. Results: Myocardial uptake showed significant correlations with BMI (r = −0.162, p = 0.018), HbA1c (r = −0.150, p = 0.030), and triglyceride levels (r = −0.137, p = 0.046). No other clinical variables showed a significant correlation with myocardial glucose uptake. After multiple linear regression analysis, BMI (p = 0.032) and HbA1c (p = 0.050) showed a correlation with MGUR. In group analysis, after dividing patients based on BMI, the obese group showed significantly lower myocardial uptake than the non-obese group (3.8 ± 1.9 vs. 4.4 ± 2.1, p = 0.031). Conclusions: Among several clinical variables, BMI and HbA1c levels were related to myocardial glucose uptake. A prospective study would be needed to examine whether a protocol that additionally considers BMI and HbA1c levels is necessary for the current cardiac FDG PET protocol. [ABSTRACT FROM AUTHOR]

Background: Heart failure (HF) is a complex disease and inflammation play a crucial role in its pathophysiology. The metabolism of energy substrate alters in HF and these changes may lead to the impairment in amino acid (AA) metabolism by increasing the heart's dependence on AAs. Limited studies evaluated the relationship between inflammation and AA profile in patients with HF. In this study, we aimed to evaluate the AA profile in patients with HF and to reveal its relationship with inflammation. Materials and Methods: Seventy-two patients with HF and 64 healthy controls were included in this study. C-reactive protein/albumin ratio (CAR) was used to assess inflammatory status of the patients. High performance liquid chromatography technique was used to evaluate the AA profile. Results: We detected that AAs profile was significantly changed in HF patients compared to controls. HF patients had also significantly higher CAR (p<0.001) level. The best cut-off value of CAR for predicting HF was 0.91, and patients were divided into 2 groups according to this cut-off value: CAR≥0.91 (high inflammation group) and CAR<0.91 (low inflammation group). When compared to low inflammation, patients with high inflammation had significantly different AAs profile. Correlation analysis showed that CAR was positively correlated with phenylalanine, tyrosine and asparagine whereas negatively correlated with valine, leucine and methionine levels. Conclusion: We found that AA profile was significantly changed in patients with HF. Also, the impairment in AA metabolism was more pronounced in patients with higher inflammation compared to patients with lower inflammation. We suggest that main mechanism underlying the impaired AA profile in HF may be increased inflammation. [ABSTRACT FROM AUTHOR]

The 12th annual Utah Cardiac Recovery Symposium (U-CARS) in 2024 continued its mission to advance cardiac recovery by uniting experts across various fields. The symposium featured key presentations on cutting-edge topics such as CRISPR gene editing for heart failure, guideline-directed medical therapy for heart failure (HF) with improved/recovered ejection fraction (HFimpEF), the role of extracorporeal cardiopulmonary resuscitation (ECPR) in treating cardiac arrest, and others. Discussions explored genetic and metabolic contributions to HF, emphasized the importance of maintaining pharmacotherapy in HFimpEF to prevent relapse, and identified future research directions including refining ECPR protocols, optimizing patient selection, and leveraging genetic insights to enhance therapeutic strategies. [ABSTRACT FROM AUTHOR]

Myocardial recovery is characterized by a return toward normal structure and function of the heart after an injury. Mechanisms of myocardial recovery include restoration and/or adaptation of myocyte structure and function, mitochondrial activity and number, metabolic homeostasis, electrophysiological stability, extracellular matrix remodeling, and myocardial perfusion. Myocardial regeneration is an element of myocardial recovery that involves the generation of new myocardial tissue, a process which is limited in adult humans but may be therapeutically augmented. Understanding the mechanisms of myocardial recovery and myocardial regeneration will lead to novel therapies for heart failure. [ABSTRACT FROM AUTHOR]

Diabetic cardiomyopathy (DbCM) is a common complication in individuals with type 2 diabetes mellitus (T2DM), and its exact pathogenesis is still debated. It was hypothesized that chronic hyperglycemia and insulin resistance activate critical cellular pathways that are responsible for numerous functional and anatomical perturbations in the heart. Interstitial inflammation, oxidative stress, myocardial apoptosis, mitochondria dysfunction, defective cardiac metabolism, cardiac remodeling, hypertrophy and fibrosis with consequent impaired contractility are the most common mechanisms implicated. Epigenetic changes also have an emerging role in the regulation of these crucial pathways. The aim of this review was to highlight the increasing knowledge on the molecular mechanisms of DbCM and the new therapies targeting specific pathways. [ABSTRACT FROM AUTHOR]

Hypothyroidism has adverse effects on heart metabolism and functions including reduced heart rate, cardiac output and cardiac contractility. The therapeutic effects of alpha lipoic acid (LA) and metformin (MET) against hypothyroidism-induced myocardial complications were assessed in the current study. Rats were divided into control, propylthiouracil (PTU)-induced hypothyroidism model, hypothyroidism model treated with LA and/or MET. Serum thyroid hormones (T3, T4 and TSH) were measured. Lipid peroxidation (MDA), nitric oxide (NO), reduced glutathione (GSH), nuclear factor erythroid 2–related factor 2 (NrF2), B-cell lymphoma 2 (BCL2), nuclear factor kappa B (NF-κB), serotonin (5-HT), norepinephrine (NE) and dopamine (DA), acetylcholinesterase (AChE), monoamine oxidase (MAO) and Na+,K+,ATPase were measured in the cardiac tissue. The histopathological changes were also assessed. PTU significantly decreased T3 and T4 and significantly increased TSH. A significant increase in MDA, GSH, NrF2, BCL2, NF-κB, 5-HT, NE, DA, AChE, MAO and Na+,K+,ATPase and a significant decrease in NO were observed in the cardiac tissue of hypothyroidism model. This was associated with histopathological changes. LA alone or with MET restored T3 and TSH and improved almost all the biochemical changes except the decreased NO and the increased DA. MET restored T3, T4 and TSH and the biochemical changes induced in the cardiac tissue. MET ameliorated the histopathological changes that were still observed with LA alone or with MET. The present findings indicate that MET had cardioprotective effect against hypothyroidism and its myocardial complications. This effect was less prominent with LA alone or in combination with MET. [ABSTRACT FROM AUTHOR]

One of the pathological characteristics of obesity is fat accumulation of skeletal muscles (SKM) and the myocardium, involving mechanisms of insulin resistance and abnormal lipid metabolism. Apolipoprotein A-IV (ApoA-IV) is an essential gene in both glucose and lipid metabolisms. Using high-fat diet (HFD) induced obese apoA-IV-knockout mice and subsequent introduction of exogenous recombinant-ApoA-IV protein and adeno-associated virus (AAV)-transformed apoA-IV, we examined lipid metabolism indicators of SKM and the myocardium, which include triglyceride (TG) content, RT-PCR for lipogenic indicators and western blotting for AKT phosphorylation. Similarly, we used high-glucose-fed or palmitate (Pal)-induced C2C12 cells co-cultured with ApoA-IV protein to evaluate glucose uptake, the phosphoinositide 3-kinase (PI3K)–AKT pathway, and lipid metabolisms. In stable obese animal models, we find ApoA-IV-knockout mice show elevated TG content, enhanced expression of lipogenic enzymes and diminished phosphorylated AKT in SKM and the myocardium, but both stable hepatic expression of AAV-apoA-IV and brief ApoA-IV protein administration suppress lipogenesis and promote AKT phosphorylation. In a myoblast cell line C2C12, ApoA-IV protein suppresses Pal-induced lipid accumulation and lipogenesis but enhances AKT activation and glucose uptake, and the effect is abolished by a PI3K inhibitor. We find that ApoA-IV reduces fat accumulation by suppressing lipogenesis and improves glucose uptake in SKM and the myocardium by regulating the PI3K–AKT pathway. [ABSTRACT FROM AUTHOR]

Mitochondrial fusion and fission accompany adaptive responses to stress and altered metabolic demands. Inner membrane fusion and cristae morphogenesis depends on optic atrophy 1 (Opa1), which is expressed in different isoforms and is cleaved from a membrane-bound, long to a soluble, short form. Here, we have analyzed the physiological role of Opa1 isoforms and Opa1 processing by generating mouse lines expressing only one cleavable Opa1 isoform or a non-cleavable variant thereof. Our results show that expression of a single cleavable or non-cleavable Opa1 isoform preserves embryonic development and the health of adult mice. Opa1 processing is dispensable under metabolic and thermal stress but prolongs life span and protects against mitochondrial cardiomyopathy in OXPHOS-deficient Cox10-/- mice. Mechanistically, loss of Opa1 processing disturbs the balance between mitochondrial biogenesis and mitophagy, suppressing cardiac hypertrophic growth in Cox10-/- hearts. Our results highlight the critical regulatory role of Opa1 processing, mitochondrial dynamics, and metabolism for cardiac hypertrophy. [ABSTRACT FROM AUTHOR]

Cardiovascular disease and cancer are the two leading causes of morbidity and mortality in the world. The emerging field of cardio-oncology described several shared risk factors that predispose patients to both cardiovascular disease and cancer. Post-acute COVID-19 syndrome is a chronic condition that occurs in many patients who have experienced a SARS-CoV-2 infection, mainly based on chronic fatigue, sedentary lifestyle, cramps, breathing difficulties, and reduced lung performance. Post-acute COVID-19 exposes patients to increased visceral adiposity, insulin resistance, myosteatosis, and white adipose tissue content (surrounded by M1 macrophages and characterized by a Th1/Th17 phenotype), which increases the risk of cardiovascular mortality and cancer recurrence. In this review, the main metabolic affections of post-acute COVID-19 syndrome in cancer patients at low and high risk of cardiomyopathies will be summarized. Furthermore, several non-pharmacological strategies aimed at reducing atherosclerotic and cardiac risk will be provided, especially through anti-inflammatory nutrition with a low insulin and glycemic index, appropriate physical activity, and immune-modulating bioactivities able to reduce visceral obesity and myosteatosis, improving insulin-related signaling and myocardial metabolism. [ABSTRACT FROM AUTHOR]

Aims Women with angina and non-obstructive coronary artery disease (ANOCA) have a heightened risk for cardiovascular events, and the pathophysiology for ischaemic symptoms may be related to alterations in microvascular structure and function. We examined the use of breathing-enhanced oxygenation-sensitive cardiac magnetic resonance imaging (OS-CMR) using vasoactive breathing manoeuvres to assess myocardial oxygenation in women with ANOCA. Methods and results We recruited women (aged 40–65 years) from two sites in Canada who presented to healthcare with persistent retrosternal chest pain and found to have ANOCA, or without a history of cardiovascular disease. All participants were scanned using a clinical 3T MRI scanner, and OS-CMR images were acquired over a breath hold following paced hyperventilation to measure global and regional measurements of heterogeneity. Fifty-four women with ANOCA (age: 55 ± 6.2 years) and 48 healthy controls (age: 51.2 ± 4.8 years) were recruited. There was no significant difference in volume, function, mass, or global myocardial oxygenation between the two groups [mean %Δ in signal intensity (SI): 4.9 (±7.3) vs. 4.5 (±10.1), P = 0.82]. Women with ANOCA had higher regional variations in myocardial oxygenation in circumferential [median %Δ in SI: 5.1 (2.0–7.6) vs. 2.2 (1.4–3.5), P = 0.0004] and longitudinal directions [median %Δ in SI: 11.4 (5.4–16.7) vs. 6.0 (3.0–7.0), P = 0.001], which remained present in a multivariate model. Conclusion Heterogeneous myocardial oxygenation may explain ischaemic symptoms without any associated epicardial obstructive coronary artery disease. Regional variations in myocardial oxygenation on OS-CMR could serve as an important diagnostic marker for microvascular dysfunction in women with ANOCA. [ABSTRACT FROM AUTHOR]

Background. Patients with β‐thalassemia major depend on lifelong transfusion, resulting in tissue iron overload. This longitudinal retrospective observational study aims to assess myocardial and liver iron overload using magnetic resonance imaging (MRI) and investigate the lag between myocardial and liver iron unloading in β‐thalassemia patients undergoing chelation therapy. Methods. Beta‐thalassemia major patients with at least two MRI studies between 2016 and 2020 were enrolled. Myocardial and liver iron overload were defined as T2∗ less than 20 and 2.1, respectively. Outcomes included mortality, myocardial and liver T2∗ changes, and systolic dysfunction assessed by cardiac MRI. Results. Fifty‐five patients with a mean age of 24.62 ± 7.94 years, a mean follow‐up duration of 24.3 ± 12.9 months, and a mean ferritin level of 1475.75 ± 771.12 ng/mL were enrolled. All of the abovementioned patients only took deferoxamine as the iron‐chelating medication. Mortality occurred in three patients (5.5%) during follow‐up. Liver T2∗ significantly increased (p value <0.05), while myocardial T2∗ showed a nonsignificant increase. Iron unloading of the myocardium was not significantly different from that of the liver and did not result in a significant lag (56% vs. 44%; p value = 0.419). Baseline myocardial T2∗ correlated with extramedullary hematopoiesis, weekly number of deferoxamine injections (p value <0.01), timing between the transfusions, and serum ferritin (p value <0.05). Conclusion. Liver T2∗ reduced during deferoxamine chelation therapy, while myocardial T2∗ remained unchanged. No significant lag was observed between myocardial and liver iron unloading. Further studies are required to elucidate these findings. [ABSTRACT FROM AUTHOR]

The future of healthcare for cardiovascular diseases holds immense promise, not only based in new discoveries in cardiac metabolism but also in translating them to solutions for critical challenges faced by society. Here, ten scientists share their insights, shedding light on the future that lies ahead for this field. [ABSTRACT FROM AUTHOR]

The adult mammalian cardiomyocyte has a limited capacity for self-renewal, which leads to the irreversible heart dysfunction and poses a significant threat to myocardial infarction patients. In the past decades, research efforts have been predominantly concentrated on the cardiomyocyte proliferation and heart regeneration. However, the heart is a complex organ that comprises not only cardiomyocytes but also numerous noncardiomyocyte cells, all playing integral roles in maintaining cardiac function. In addition, cardiomyocytes are exposed to a dynamically changing physical environment that includes oxygen saturation and mechanical forces. Recently, a growing number of studies on myocardial microenvironment in cardiomyocyte proliferation and heart regeneration is ongoing. In this review, we provide an overview of recent advances in myocardial microenvironment, which plays an important role in cardiomyocyte proliferation and heart regeneration. [ABSTRACT FROM AUTHOR]

AbstractObjectivesMethodsKey findingsConclusionsExperimental models to test the effective protection against cardiac ischemia injury are still challenging in pre-clinical studies. The use of myocardial slices creates a special link between testing isolated cardiomyocytes and whole-heart research. In this work, we investigated the effects of oxygen deprivation in a hypoxic chamber and treatment with cobalt chloride (CoCl2) on the nucleotide profile in isolated mouse myocardial slices.200 μm-thick left ventricle myocardial slices were obtained from 3-month-old male C57Bl/6J mice using an oscillatory microtome. Slices were then exposed to 1% O2 atmosphere or 100 μM CoCl2 at 37 °C for 45 min and used for nucleotide measurements using ultra-high-performance liquid chromatography. The effects of two short-term experimental models of hypoxia were compared to 2′-deoxyglucose with oligomycin (2-DG + OLIGO) treatment, which inhibited both glycolysis and mitochondrial ATP synthesis.A significant effect of hypoxia with 1% O2 was observed on adenosine triphosphate (ATP) and total adenine nucleotide (TAN) concentrations as well as on adenylate energy charge (AEC), ATP/ADP and ATP/AMP ratios. Oxygen deprivation caused changes almost as profound as 2-DG + OLIGO, emphasizing the critical role of mitochondrial oxidative phosphorylation in the energy metabolism of cultured heart slices. CoCl2 treatment that elicits hypoxia-like responses via HIF-1α stabilization only slightly affected nucleotide levels. This suggests that mechanisms induced by cobalt ions require more time to change the cardiac energy metabolism.A short-term culture of myocardial slices in a hypoxic chamber seems to be an appropriate model of cardiac ischemia for testing new pharmacological approaches based on modulating the energy metabolism of cardiac cells. [ABSTRACT FROM AUTHOR]