Abstract 12622: Western Diet for One Month Impairs Myocardial Energetics and Both Systolic and Diastolic Pump Function in the Mouse Heart

Background and Significance: Metabolic heart disease(MHD) is common in patients with obesity, type 2 diabetes and/or metabolic syndrome. We found cardiac mitochondrial dysfunction in mice with obesity-related MHD due to consumption of a high fat high sucrose (HFHS) diet. The effects of diet-induced obesity on cardiac energetics and pump function in the intact organ are largely unknown. Hypothesis: We tested the hypothesis that cardiac mitochondrial dysfunction due to HFHS diet for one month impairs energetic and contractile reserve in the intact heart. Methods and Results: Mice were fed a HFHS or control diet (CD) for 1 month. In isolated cardiac mitochondria from HFHS-fed mice (vs. CD) the maximal rate of ATP synthesis was decreased for complex I (down by 42%; p<0.05) and II (down by 37%; p<0.05) substrates. We measured myocardial energetics in isolated perfused hearts using 31P NMR spectroscopy at baseline (450 bpm, 2 mM Ca++) and high workload (600 bpm, 4 mM Ca++) in HFHS (n=7) and CD (n=8) hearts. In HFHS-fed hearts, myocardial ATP concentration was the same at baseline (10.5±0.4 vs 10.4±0.5 mM) and high workload (7.4±0.9 vs. 7.5±0.5 mM) as that of CD hearts. However, in HFHS-fed hearts the concentration of phosphocreatine, which reflects energy reserve, was decreased at baseline (13±0.7 vs. 17.5±0.8 mM; p<0.01) and decreased further at high workload (down to 7.3±0.7; p<0.01 vs. baseline and p<0.01 vs. CD at 10.5±0.4 mM) - indicating a mismatch between ATP production and utilization. In HFHS hearts, the diastolic pressure-volume relationship was shifted upward and leftward at baseline, indicative of diastolic dysfunction. In HFHS hearts, baseline systolic function was preserved (rate pressure product 41,600±2,200 vs. 41,000±2,000 mmHg/min), but was decreased at high workload (54,800±7,200 vs. 85,300±4,300 mmHg/min; p<0.01 vs. CD), reflecting an impaired contractile reserve. Conclusion: Consumption of a HFHS diet for one month causes cardiac mitochondrial dysfunction with reduced ATP synthesis leading to impaired energetic reserve in the intact heart. Diastolic dysfunction at rest and the impaired ability to increase systolic function with increased work demands may result from impaired energetics in MHD.

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Utility and limitations of ejection fraction and of diastolic dysfunction in heart failure patients

Monaldi Archives for Chest Disease ◽

10.4081/monaldi.2019.1058 ◽

2019 ◽

Vol 89 (1) ◽

Cited By ~ 1

Author(s):

Gian Francesco Mureddu ◽

Andrea Faggiano

Keyword(s):

Heart Failure ◽

Ejection Fraction ◽

Diastolic Dysfunction ◽

Systolic Function ◽

Myocardial Strain ◽

Left Ventricular ◽

Contractile Reserve ◽

Load Dependence ◽

Echocardiographic Evaluation ◽

Lv Systolic Function

The echocardiographic evaluation of left ventricular (LV) systolic function, and especially of ejection fraction (EF) plays a central role in the diagnosis of heart failure (HF) due to its undisputed prognostic value. Limitations of EF are substantially: i) the variability and reproducibility of measurements, and ii) the load-dependence. Measurement of stroke volume, longitudinal function and myocardial strain can overcome the limitations of EF in assessing the contractile reserve of patients with HF and may help to define both the phenotype and prognosis of the disease. The recognition of diastolic dysfunction (mainly by echocardiography) is the pathophysiological basis to make diagnosis of HF with preserved ejection fraction (HFpEF). The limitations are essentially related to its feasibility, since performing a multi-parametric quantitative echocardiographic evaluation, as indicated by the guidelines, may be difficult in clinical practice. Difficulties in method standardization, the poor attitude of cardiologists to test their reproducibility (test-retest, variability) favor the evaluation “at-a-glance” of LV structural and functional LV abnormalities.

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Human Trisomic iPSCs from Down Syndrome Fibroblasts Manifest Mitochondrial Alterations Early during Neuronal Differentiation

Biology ◽

10.3390/biology10070609 ◽

2021 ◽

Vol 10 (7) ◽

pp. 609

Author(s):

Nunzia Mollo ◽

Matteo Esposito ◽

Miriam Aurilia ◽

Roberta Scognamiglio ◽

Rossella Accarino ◽

...

Keyword(s):

Down Syndrome ◽

Mitochondrial Dysfunction ◽

Neuronal Differentiation ◽

Expression Profiles ◽

Meta Analysis ◽

Atp Synthesis ◽

Differentiation Markers ◽

Differentiation Potential ◽

Atp Production ◽

Mitochondrial Alterations

Background: The presence of mitochondrial alterations in Down syndrome suggests that it might affect neuronal differentiation. We established a model of trisomic iPSCs, differentiating into neural precursor cells (NPCs) to monitor the occurrence of differentiation defects and mitochondrial dysfunction. Methods: Isogenic trisomic and euploid iPSCs were differentiated into NPCs in monolayer cultures using the dual-SMAD inhibition protocol. Expression of pluripotency and neural differentiation genes was assessed by qRT-PCR and immunofluorescence. Meta-analysis of expression data was performed on iPSCs. Mitochondrial Ca2+, reactive oxygen species (ROS) and ATP production were investigated using fluorescent probes. Oxygen consumption rate (OCR) was determined by Seahorse Analyzer. Results: NPCs at day 7 of induction uniformly expressed the differentiation markers PAX6, SOX2 and NESTIN but not the stemness marker OCT4. At day 21, trisomic NPCs expressed higher levels of typical glial differentiation genes. Expression profiles indicated that mitochondrial genes were dysregulated in trisomic iPSCs. Trisomic NPCs showed altered mitochondrial Ca2+, reduced OCR and ATP synthesis, and elevated ROS production. Conclusions: Human trisomic iPSCs can be rapidly and efficiently differentiated into NPC monolayers. The trisomic NPCs obtained exhibit greater glial-like differentiation potential than their euploid counterparts and manifest mitochondrial dysfunction as early as day 7 of neuronal differentiation.

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Ca2+ overload- and ROS-associated mitochondrial dysfunction contributes to δ-tocotrienol-mediated paraptosis in melanoma cells

APOPTOSIS ◽

10.1007/s10495-021-01668-y ◽

2021 ◽

Author(s):

Michela Raimondi ◽

Fabrizio Fontana ◽

Monica Marzagalli ◽

Matteo Audano ◽

Giangiacomo Beretta ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Cell Death ◽

Mitochondrial Dysfunction ◽

Atp Synthesis ◽

Melanoma Cells ◽

Human Melanoma ◽

Ros Generation ◽

Therapy Outcomes ◽

Human Melanoma Cells ◽

Oxphos Complex

Abstract Melanoma is an aggressive tumor with still poor therapy outcomes. δ-tocotrienol (δ-TT) is a vitamin E derivative displaying potent anti-cancer properties. Previously, we demonstrated that δ-TT triggers apoptosis in human melanoma cells. Here, we investigated whether it might also activate paraptosis, a non-canonical programmed cell death. In accordance with the main paraptotic features, δ-TT was shown to promote cytoplasmic vacuolization, associated with endoplasmic reticulum/mitochondrial dilation and protein synthesis, as well as MAPK activation in A375 and BLM cell lines. Moreover, treated cells exhibited a significant reduced expression of OXPHOS complex I and a marked decrease in oxygen consumption and mitochondrial membrane potential, culminating in decreased ATP synthesis and AMPK phosphorylation. This mitochondrial dysfunction resulted in ROS overproduction, found to be responsible for paraptosis induction. Additionally, δ-TT caused Ca2+ homeostasis disruption, with endoplasmic reticulum-derived ions accumulating in mitochondria and activating the paraptotic signaling. Interestingly, by using both IP3R and VDAC inhibitors, a close cause-effect relationship between mitochondrial Ca2+ overload and ROS generation was evidenced. Collectively, these results provide novel insights into δ-TT anti-melanoma activity, highlighting its ability to induce mitochondrial dysfunction-mediated paraptosis. Graphic Abstract δ-tocotrienol induces paraptotic cell death in human melanoma cells, causing endoplasmic reticulum dilation and mitochondrial swelling. These alterations induce an impairment of mitochondrial function, ROS production and calcium overload.

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Diastolic dysfunction in a pre-clinical model of diabetes is associated with changes in the cardiac non-myocyte cellular composition

Cardiovascular Diabetology ◽

10.1186/s12933-021-01303-9 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Charles D. Cohen ◽

Miles J. De Blasio ◽

Man K. S. Lee ◽

Gabriella E. Farrugia ◽

Darnel Prakoso ◽

...

Keyword(s):

Bone Marrow ◽

Flow Cytometry ◽

Diastolic Dysfunction ◽

Systolic Function ◽

Cardiac Fibroblasts ◽

Detailed Examination ◽

Diabetic Mice ◽

Cellular Mechanisms ◽

Clinical Model ◽

Cardiac Ventricles

Abstract Background Diabetes is associated with a significantly elevated risk of cardiovascular disease and its specific pathophysiology remains unclear. Recent studies have changed our understanding of cardiac cellularity, with cellular changes accompanying diabetes yet to be examined in detail. This study aims to characterise the changes in the cardiac cellular landscape in murine diabetes to identify potential cellular protagonists in the diabetic heart. Methods Diabetes was induced in male FVB/N mice by low-dose streptozotocin and a high-fat diet for 26-weeks. Cardiac function was measured by echocardiography at endpoint. Flow cytometry was performed on cardiac ventricles as well as blood, spleen, and bone-marrow at endpoint from non-diabetic and diabetic mice. To validate flow cytometry results, immunofluorescence staining was conducted on left-ventricles of age-matched mice. Results Mice with diabetes exhibited hyperglycaemia and impaired glucose tolerance at endpoint. Echocardiography revealed reduced E:A and e’:a’ ratios in diabetic mice indicating diastolic dysfunction. Systolic function was not different between the experimental groups. Detailed examination of cardiac cellularity found resident mesenchymal cells (RMCs) were elevated as a result of diabetes, due to a marked increase in cardiac fibroblasts, while smooth muscle cells were reduced in proportion. Moreover, we found increased levels of Ly6Chi monocytes in both the heart and in the blood. Consistent with this, the proportion of bone-marrow haematopoietic stem cells were increased in diabetic mice. Conclusions Murine diabetes results in distinct changes in cardiac cellularity. These changes—in particular increased levels of fibroblasts—offer a framework for understanding how cardiac cellularity changes in diabetes. The results also point to new cellular mechanisms in this context, which may further aid in development of pharmacotherapies to allay the progression of cardiomyopathy associated with diabetes.

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Long-term levosimendan treatment improves systolic function and myocardial relaxation in mice with cardiomyocyte-specific disruption of the Serca2 gene

Journal of Applied Physiology ◽

10.1152/japplphysiol.01044.2012 ◽

2013 ◽

Vol 115 (10) ◽

pp. 1572-1580 ◽

Cited By ~ 7

Author(s):

Vigdis Hillestad ◽

Frank Kramer ◽

Stefan Golz ◽

Andreas Knorr ◽

Kristin B. Andersson ◽

...

Keyword(s):

Gene Expression ◽

Heart Failure ◽

Cardiac Function ◽

Diastolic Dysfunction ◽

Systolic Function ◽

Cytosolic Calcium ◽

Left Ventricular ◽

Pressure Measurements ◽

Human Heart Failure

In human heart failure (HF), reduced cardiac function has, at least partly, been ascribed to altered calcium homeostasis in cardiomyocytes. The effects of the calcium sensitizer levosimendan on diastolic dysfunction caused by reduced removal of calcium from cytosol in early diastole are not well known. In this study, we investigated the effect of long-term levosimendan treatment in a murine model of HF where the sarco(endo)plasmatic reticulum ATPase ( Serca) gene is specifically disrupted in the cardiomyocytes, leading to reduced removal of cytosolic calcium. After induction of Serca2 gene disruption, these mice develop marked diastolic dysfunction as well as impaired contractility. SERCA2 knockout (SERCA2KO) mice were treated with levosimendan or vehicle from the time of KO induction. At the 7-wk end point, cardiac function was assessed by echocardiography and pressure measurements. Vehicle-treated SERCA2KO mice showed significantly diminished left-ventricular (LV) contractility, as shown by decreased ejection fraction, stroke volume, and cardiac output. LV pressure measurements revealed a marked increase in the time constant (τ) of isovolumetric pressure decay, showing impaired relaxation. Levosimendan treatment significantly improved all three systolic parameters. Moreover, a significant reduction in τ toward normalization indicated improved relaxation. Gene-expression analysis, however, revealed an increase in genes related to production of the ECM in animals treated with levosimendan. In conclusion, long-term levosimendan treatment improves both contractility and relaxation in a heart-failure model with marked diastolic dysfunction due to reduced calcium transients. However, altered gene expression related to fibrosis was observed.

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Abstract P233: Diabetic Cardiomyopathy is Reversed by Increased Mitochondrial Bioenergetics Due to PGC-1α Activation by EET Treatment of Obese Mice

Hypertension ◽

10.1161/hyp.68.suppl_1.p233 ◽

2016 ◽

Vol 68 (suppl_1) ◽

Author(s):

Jian Cao ◽

John A McClung ◽

Shailendra P Singh ◽

Lars Bellner ◽

Maayan Waldman ◽

...

Keyword(s):

Heart Failure ◽

Insulin Resistance ◽

Oxidative Phosphorylation ◽

Mitochondrial Dysfunction ◽

Diabetic Cardiomyopathy ◽

Cardiac Fibrosis ◽

Systolic Function ◽

Control Group ◽

Protein Markers ◽

Obesity And Diabetes

Introduction: Obesity and diabetes are associated with progressive cardiac fibrosis that, sequentially, results in diastolic dysfunction, reduced contractility, and ultimately heart failure. Contributing factors include hyperglycemia, insulin resistance, mitochondrial dysfunction, and a reduction in AMPK signaling. PGC-1α activates mitochondrial biogenesis and oxidative phosphorylation and is decreased in patients with diabetes mellitus (DM). We hypothesize that an epoxyeicosatrienoic acids (EETs) agonist (EET-A) will increase PGC-1α levels in a db mouse model of DM attenuate cardiomyopathy, and prevent heart failure. Methods: Db mice (4-wks), were allowed to acclimatize for 16-wks and were then divided into 3 treatment groups for an additional 16 wks: A) control, B) EET-A 1.5mg/100g BW 2 weeks and C) EET-A-Ln-PGC-1α shRNA. Ln-PGC-1α shRNA suppressed PGC-1α protein in heart tissue by 40-50%. Oxygen consumption (VO 2 ), and blood glucose was determined. Heart tissues were harvested to measure PGC-1α, HO-1, pAMPK, PGC-1α, echocardiographic fractional shortening, mitochondrial oxidative phosphorylation (OXPHOS) and mitofusion protein markers. Results: All mice developed heart failure by the end of 16 weeks and were characterized by a decrease in myocardial contractility, an increase in insulin resistance and blood pressure, decreased VO 2 , the appearance of mitochondria dysfunction and a decrease in AMPK and downstream PGC-1α signaling. Mice treated with EET-A demonstrated an increase in PGC-1α levels, improved mitochondrial function and oxidative phosphorylation (p<0.01 vs control), increased NO bioavailability (p<0.05 vs control), and normalization of glucose metabolism, insulin levels, VO 2 and LV systolic function (p<0.05 vs control). All of these findings were suppressed by PGC-1α inhibition which was accompanied by the onset of even more severe LV dysfunction than in the control group. Conclusion: Increased EET levels result in activation of PGC-1α-HO-1 which reverses diabetes induced insulin resistance, mitochondrial dysfunction, and cardiomyopathy. EET may have potential as a powerful agent for therapeutic application in the treatment of diabetic cardiomyopathy.

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Abstract 90: Bendavia (MTP-131), a Novel Mitochondria-Targeting Peptide, Improves ADP-Stimulated Mitochondrial Respiration in Cardiomyocytes Isolated From Dogs with Chronic Heart failure

Circulation Research ◽

10.1161/res.115.suppl_1.90 ◽

2014 ◽

Vol 115 (suppl_1) ◽

Author(s):

Hani Sabbah ◽

Ramesh C Gupta ◽

Sharad Rastogi ◽

Paula Mohyi ◽

Kristina Szekely

Keyword(s):

Heart Failure ◽

Mitochondrial Respiration ◽

Systolic Function ◽

Atp Synthesis ◽

Vehicle Control ◽

Electrode System ◽

Lv Function ◽

Targeting Peptide ◽

Lv Systolic Function ◽

Mitochondria Targeting

Background: Mitochondria (MITO) of failed human hearts and hearts of dogs with experimental heart failure (HF) manifest structural and functional abnormalities characterized by hyperplasia and reduced organelle size and reduced respiration. These abnormalities lead to reduced ATP synthesis that adversely impacts LV function. We previously showed that chronic therapy (3 months) with Bendavia (MTP-131), a novel mitochondria-targeting peptide, improves LV systolic function in dogs with heart failure (HF), reverses MITO abnormalities and normalizes mitochondria ATP synthesis in myocardium from Bendavia-treated HF dogs. In the present study we examined the direct effects of Bendavia on mitochondria ADP-stimulated state 3 respiration in freshly isolated cardiomyocytes from dogs with advanced chronic HF. Methods: Cardiomyocytes were isolated from LV free wall of 3 untreated dogs with HF produced by intracoronary microembolizations (LV ejection fraction <30%). A standard collagenase-based enzymatic process was used for isolation that yielded ~70% viable rod-shaped cardiomyocytes that excluded trypan blue. Equal aliquotes of cardiomyocytes were incubated in 0, 0.01, 0.10, 1.0 and 10 μM concentration of Bendavia for one hour at 37°C. At the end of incubation, ADP-stimulated state-3 respiration was measured using a Clark electrode system and quatified in nAtom Oxygen/min/mg protein. Results: State-3 respiration in the absence of Bendavia (Vehicle-Control) was 248±9 nAtom Oxygen/min/mg protein. Compared to vehicle-control, incubation of failing cardiomyocytes with Bendavia significantly increased state-3 respiration to 303±33 at 0.01 μM, p<0.05; 405±39 at 0.10 μM, p<0.05; 371±28 at 1.0 μM, p<0.05; and 346±29 at 10.0 μM, p<0.05. Conclusions: Results of this study indicate that the effects of Bendavia on mitochondrial respiration in cardiomyocytes is direct and not a consequence of improved global LV structure or function. Furthermore, the results indicate that the improvement in mitochondrial respiration after treatment with Bendavia can occur early after initiation of therapy (within one hour) and is dose-dependent up to concentrations of 0.10 μM.

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Abstract 15315: SGLT2 Inhibitor Ertugliflozin Decreases Elevated Intracellular Sodium, Improves Myocardial Energetics and Enhances Function in Metabolic Heart Disease

Circulation ◽

10.1161/circ.142.suppl_3.15315 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Dominique Croteau ◽

Tomas Baka ◽

Sara Young ◽

Huamei He ◽

David R Pimentel ◽

...

Keyword(s):

Heart Failure ◽

Heart Disease ◽

Contractile Function ◽

Control Diet ◽

Sglt2 Inhibitor ◽

Atp Synthesis ◽

Intracellular Sodium ◽

Contractile Reserve ◽

Isolated Hearts ◽

Metabolic Heart Disease

Background: Sodium-glucose co-transporter 2 (SGLT2) inhibitors are antidiabetic drugs of great interest in cardiology due to their improvement of heart failure outcomes independent of diabetes. As SGLT2 is not expressed in cardiomyocytes, the mechanism of such benefit remains unclear. Elevated myocardial intracellular sodium [Na + ] i has been found in heart failure and SGLT2 inhibition lowers [Na + ] i in isolated cardiomyocytes. Elevated [Na + ] i was shown to decrease mitochondrial calcium via mitochondrial Na/Ca exchanger (NCx MITO ), resulting in decreased mitochondrial ATP synthesis. We have previously shown that mice fed a diet high in fat and sugar (HFHS) develop metabolic heart disease (MHD) characterized by decreased mitochondrial ATP synthesis with decreased phosphocreatine (PCr), worsened diastolic function and contractile reserve. We hypothesize that the SGLT2 inhibitor ertugliflozin (ERTU) decreases the elevated [Na + ] i to improve energetics and contractile function in MHD. Methods and Results: Isolated hearts from mice after 6 months of HFHS vs. control diet (CD), +/- ERTU in the last month, were studied using 31 P and 23 Na NMR spectroscopy to measure PCr/ATP ratio and [Na + ] i , respectively. As expected, HFHS hearts showed lower PCr/ATP, diastolic dysfunction (↑LVEDP) and lack of contractile reserve (↓RPP) during high work protocol compared to CD hearts. Myocardial [Na + ] i was elevated more than 2-fold in HFHS compared to CD. One month of ERTU treatment decreased [Na + ] i and improved energetics and contractile function in HFHS to levels similar to or better than CD. Perfusion with CGP 37157, which inhibits NCx MITO , improved PCr/ATP in HFHS hearts. Conclusion: Lowering of myocardial [Na + ] i by ertugliflozin contributes to improved energetics and function in MHD. These results suggest targeting [Na + ] i as an effective strategy to improve cardiac dysfunction in MHD and other forms of heart disease associated with elevated myocardial [Na + ] i.

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Abstract 16485: The Nitroxyl Donor 1-Nitrosocyclohexyl Acetate Limits Cardiac Superoxide Upregulation and Diastolic Dysfunction in a Mouse Model of Diabetic Cardiomyopathy

Circulation ◽

10.1161/circ.130.suppl_2.16485 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Rebecca H Ritchie ◽

Nga Cao ◽

Yung George Wong ◽

Sarah Rosli ◽

Helen Kiriazis ◽

...

Keyword(s):

Heart Failure ◽

Mouse Model ◽

Diastolic Dysfunction ◽

Diabetic Cardiomyopathy ◽

Ex Vivo ◽

Systolic Function ◽

Left Ventricular ◽

Cardiomyocyte Hypertrophy ◽

Lv Diastolic Dysfunction ◽

The Impact

Nitroxyl (HNO), a redox congener of NO•, is a novel regulator of cardiovascular function combining vasodilator and positive inotropic properties. Our previous studies have demonstrated these properties occur concomitantly in the intact heart; HNO moreover also exhibits antihypertrophic and superoxide-suppressing actions. HNO donors may thus offer favorable actions in heart failure. The impact of chronic HNO donor administration has however yet to be reported in this context. We tested the hypothesis that the HNO donor 1-nitrosocyclohexyl acetate (1-NCA) limits cardiomyocyte hypertrophy and left ventricular (LV) diastolic dysfunction in a mouse model of diabetic cardiomyopathy in vivo. Male 6 week-old FVB/N mice received either streptozotocin (55 mg/kg/day i.p. for 5 days, n=17), to induce type 1 diabetes, or citrate vehicle (n=16). After 4 weeks of hyperglycemia, mice were allocated to 1-NCA therapy (83mg/kg/day i.p.) or vehicle, and followed for a further 4 weeks. As shown in the table, blood glucose was unaffected by 1-NCA. LV diastolic dysfunction was evident in diabetic mice, measured as echocardiography-derived A wave velocity, deceleration time and E:A ratio; LV systolic function was preserved. Diabetes-induced diastolic dysfunction was accompanied by increased LV cardiomyocyte size, hypertrophic and pro-fibrotic gene expression, and upregulation of LV superoxide. These characteristics of diabetic cardiomyopathy were largely prevented by 1-NCA treatment. Selectivity of 1-NCA as a donor of HNO versus NO• was demonstrated by the sensitivity of the coronary vasodilation response of 1-NCA to the HNO scavenger L-cysteine (4mM), but not to the NO• scavenger hydroxocobalamin (50μM), in the normal rat heart ex vivo (n=3-7). Collectively, our studies provide the first evidence that HNO donors may represent a promising new strategy for the treatment of diabetic cardiomyopathy, and implies their therapeutic efficacy in settings of chronic heart failure.

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