scholarly journals A comprehensive analysis of myocardial substrate preference emphasizes the need for a synchronized fluxomic/metabolomic research design

2017 ◽  
Vol 312 (6) ◽  
pp. H1215-H1223 ◽  
Author(s):  
Mukundan Ragavan ◽  
Alexander Kirpich ◽  
Xiaorong Fu ◽  
Shawn C. Burgess ◽  
Lauren M. McIntyre ◽  
...  
Keyword(s):  
Myocardial Metabolism ◽  
Ketone Bodies ◽  
Tca Cycle ◽  
Oxidative Capacity ◽  
Total Carbohydrate ◽  
Atp Production ◽  
The Tca Cycle ◽  
Isotopomer Analysis ◽  
Myocardial Substrate ◽  
Correct Estimation

The heart oxidizes fatty acids, carbohydrates, and ketone bodies inside the tricarboxylic acid (TCA) cycle to generate the reducing equivalents needed for ATP production. Competition between these substrates makes it difficult to estimate the extent of pyruvate oxidation. Previously, hyperpolarized pyruvate detected propionate-mediated activation of carbohydrate oxidation, even in the presence of acetate. In this report, the optimal concentration of propionate for the activation of glucose oxidation was measured in mouse hearts perfused in Langendorff mode. This study was performed with a more physiologically relevant perfusate than the previous work. Increasing concentrations of propionate did not cause adverse effects on myocardial metabolism, as evidenced by unchanged O2 consumption, TCA cycle flux, and developed pressures. Propionate at 1 mM was sufficient to achieve significant increases in pyruvate dehydrogenase flux (3×), and anaplerosis (6×), as measured by isotopomer analysis. These results further demonstrate the potential of propionate as an aid for the correct estimation of total carbohydrate oxidative capacity in the heart. However, liquid chromotography/mass spectroscopy-based metabolomics detected large changes (~30-fold) in malate and fumarate pool sizes. This observation leads to a key observation regarding mass balance in the TCA cycle; flux through a portion of the cycle can be drastically elevated without changing the O2 consumption.

P207 Synergetic effect of amino acid and ketone metabolism underlies empagliflozin-mediated cardioprotection in the type 2 diabetic heart

2020 ◽  
Vol 41 (Supplement_1) ◽  
Author(s):  
H Kouzu ◽  
H Oshima ◽  
T Miki ◽  
A Kuno ◽  
T Sato ◽  
...  
Keyword(s):  
Amino Acid ◽  
Survival Rate ◽  
Molecular Mechanisms ◽  
Synergetic Effect ◽  
Tca Cycle ◽  
Oxidative Capacity ◽  
Metabolome Analysis ◽  
Coa Transferase ◽  
The Tca Cycle

Abstract Funding Acknowledgements Boehringer Ingelheim Background  Although emerging evidence has indicated that sodium glucose cotransporter 2 (SGLT2) inhibitors restore impaired cardiac energetics in type 2 diabetes mellitus (T2DM), the underlying molecular mechanisms have yet to be established.  Augmented utilization of ketone is one proposed hypothesis, but depletion of succinyl-CoA triggered by the conversion of ketone back to acetyl-CoA by SCOT (succinyl-CoA:3-oxoacid CoA transferase) may hamper oxidative capacity of the tricarboxylic acid (TCA) cycle, which also requires succinyl-CoA.  The recent finding that empagliflozin augments systemic amino acid metabolism in patients with T2DM led us to hypothesize that the anaplerotic effect of amino acid on the TCA cycle complements ketone oxidation. Methods and Results  Myocardial infarction (MI) was induced in T2DM rats (OLETF) and control rats (LETO).  Survival rate at 48 hours after MI was significantly lower in OLETF than in LETO (40% vs 84%), and empagliflozin treatment (10 mg/kg/day, 14 days) before MI improved the survival rate in OLETF to 70%.  Metabolome analysis was performed using heart tissues from the non-infarct region 12 hours after MI.  Using principal component analysis, data from 92 metabolites that were detected were compressed into 2 dimensions, and the first component (PC1) clearly separated empagliflozin-treated OLETF from non-treated LETO and OLETF.  Analysis of factor loading of each metabolite for PC1 revealed that branched chain amino acids leucine, isoleucine and valine, the latter two of which can be oxidized to succynyl-CoA, and β-hydroxybutyrate were the top four metabolites that characterized empagliflozin treatment.  Furthermore, in comparison to LETO, OLETF treated with empagliflozin showed 50% higher levels of glutamine and glutamate, both of which can replenish the TCA cycle at the level of α-ketoglutarate.  In OLETF, empagliflozin significantly increased the TCA cycle intermediates citrate, cis-aconitate and malate by 74%, 119% and 59%, respectively.  OLETF showed 86% higher lactate and 38% lower ATP than those in LETO, but levels of the metabolites were normalized by empagliflozin, suggesting improved glucose oxidation. Conclusions   The present analyses showed that amino acid and ketone metabolism are metabolic pathways that are most affected by empagliflozin.  Coordination of these "starvation-induced pathways" may underlie the favorable metabolic effect of empagliflozin in T2DM hearts.

Pattern of substrate utilization in vascular smooth muscle using 13C isotopomer analysis of glutamate

1998 ◽  
Vol 275 (6) ◽  
pp. H2227-H2235 ◽  
Author(s):  
Tara M. Allen ◽  
Christopher D. Hardin
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Acetyl Coa ◽  
Contractile State ◽  
The Tca Cycle ◽  
Direct Measurements ◽  
Isotopomer Analysis ◽  
13C Isotopomer Analysis

Although vascular smooth muscle (VSM) derives the majority of its energy from oxidative phosphorylation, controversy exists concerning which substrates are utilized by the tricarboxylic acid (TCA) cycle. We used 13C isotopomer analysis of glutamate to directly measure the entry of exogenous [13C]glucose and acetate and unlabeled endogenous sources into the TCA cycle via acetyl-CoA. Hog carotid artery segments denuded of endothelium were superfused with 5 mM [1-13C]glucose and 0–5 mM [1,2-13C]acetate at 37°C for 3–12 h. We found that both resting and contracting VSM preferentially utilize [1,2-13C]acetate compared with [1-13C]glucose and unlabeled substrates. The entry of glucose into the TCA cycle (30–60% of total entry via acetyl-CoA) exhibited little change despite alterations in contractile state or acetate concentrations ranging from 0 to 5 mM. We conclude that glucose and nonglucose substrates are important oxidative substrates for resting and contracting VSM. These are the first direct measurements of relative substrate entry into the TCA cycle of VSM during activation and may provide a useful method to measure alterations in VSM metabolism under physiological and pathophysiological conditions.

scholarly journals Oxygen Regulates Human Pluripotent Stem Cell Metabolic Flux

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Jarmon G. Lees ◽  
Timothy S. Cliff ◽  
Amanda Gammilonghi ◽  
James G. Ryall ◽  
Stephen Dalton ◽  
...  
Keyword(s):  
Cell Fate ◽  
Metabolic Flux ◽  
Tca Cycle ◽  
Antioxidant Response ◽  
Open Chromatin ◽  
Rna Seq ◽  
Atp Production ◽  
The Tca Cycle ◽  
Demethylase Activity ◽  
The Impact

Metabolism has been shown to alter cell fate in human pluripotent stem cells (hPSC). However, current understanding is almost exclusively based on work performed at 20% oxygen (air), with very few studies reporting on hPSC at physiological oxygen (5%). In this study, we integrated metabolic, transcriptomic, and epigenetic data to elucidate the impact of oxygen on hPSC. Using 13C-glucose labeling, we show that 5% oxygen increased the intracellular levels of glycolytic intermediates, glycogen, and the antioxidant response in hPSC. In contrast, 20% oxygen increased metabolite flux through the TCA cycle, activity of mitochondria, and ATP production. Acetylation of H3K9 and H3K27 was elevated at 5% oxygen while H3K27 trimethylation was decreased, conforming to a more open chromatin structure. RNA-seq analysis of 5% oxygen hPSC also indicated increases in glycolysis, lysine demethylases, and glucose-derived carbon metabolism, while increased methyltransferase and cell cycle activity was indicated at 20% oxygen. Our findings show that oxygen drives metabolite flux and specifies carbon fate in hPSC and, although the mechanism remains to be elucidated, oxygen was shown to alter methyltransferase and demethylase activity and the global epigenetic landscape.

Ins and Outs of the TCA Cycle: The Central Role of Anaplerosis

2021 ◽  
Vol 41 (1) ◽  
Author(s):  
Melissa Inigo ◽  
Stanisław Deja ◽  
Shawn C. Burgess
Keyword(s):  
Redox State ◽  
Tca Cycle ◽  
Oxidative Capacity ◽  
Annual Review ◽  
Publication Date ◽  
Energy Status ◽  
Cellular Energy ◽  
The Tca Cycle ◽  
Tca Cycle Intermediates

The reactions of the tricarboxylic acid (TCA) cycle allow the controlled combustion of fat and carbohydrate. In principle, TCA cycle intermediates are regenerated on every turn and can facilitate the oxidation of an infinite number of nutrient molecules. However, TCA cycle intermediates can be lost to cataplerotic pathways that provide precursors for biosynthesis, and they must be replaced by anaplerotic pathways that regenerate these intermediates. Together, anaplerosis and cataplerosis help regulate rates of biosynthesis by dictating precursor supply, and they play underappreciated roles in catabolism and cellular energy status. They facilitate recycling pathways and nitrogen trafficking necessary for catabolism, and they influence redox state and oxidative capacity by altering TCA cycle intermediate concentrations. These functions vary widely by tissue and play emerging roles in disease. This article reviews the roles of anaplerosis and cataplerosis in various tissues and discusses how they alter carbon transitions, and highlights their contribution to mechanisms of disease. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Substrate metabolism of isolated jejunal epithelium: conservation of three-carbon units

1986 ◽  
Vol 250 (2) ◽  
pp. C191-C198 ◽  
Author(s):  
R. T. Mallet ◽  
J. K. Kelleher ◽  
M. J. Jackson
Keyword(s):  
Ketone Bodies ◽  
Tca Cycle ◽  
Substrate Metabolism ◽  
Metabolic Substrates ◽  
The Tca Cycle ◽  
Carbon Compounds ◽  
Consumption Rates ◽  
14Co2 Production ◽  
Tca Cycle Intermediates ◽  
Labeling Pattern

This study characterizes the substrate metabolism of isolated jejunal epithelial cells. Utilization of substrates was assessed by spectrophotometric assay. Significant quantities of glucose, glutamine, and ketone bodies were consumed in a 1-h period; lactate and ammonia were produced. [U-14C]glucose was metabolized in this medium to approximately three moles of lactate per mole of CO2. The pattern of tricarboxylic acid (TCA) cycle metabolism was analyzed utilizing media containing different concentrations of potential metabolic substrates and trace quantities of [14C]- succinate. O2 consumption rates indicated that glutamine can serve as an energy source in the absence of other substrates. Relative 14CO2 production from [1,4-14C]succinate versus [2,3-14C]succinate, which estimates flux of TCA cycle intermediates to products other than CO2, was increased more than twofold when glutamine was the only major substrate available. Alanine was produced from TCA cycle intermediates. Analysis of the citrate labeling pattern in the presence of [2,3-14C] succinate suggested that carbon from the TCA cycle does not form a significant fraction of acetyl-CoA used for citrate synthesis and that glutamine carbon was not completely oxidized to CO2. These findings suggest that glucose and glutamine are converted to three-carbon compounds by the jejunal epithelium.

Relationship between cardiac function and substrate oxidation in hearts of diabetic rats

1997 ◽  
Vol 273 (1) ◽  
pp. H52-H58 ◽  
Author(s):  
J. C. Chatham ◽  
J. R. Forder
Keyword(s):  
Contractile Function ◽  
Systolic Pressure ◽  
Tca Cycle ◽  
Substrate Oxidation ◽  
Diabetic Rats ◽  
Diabetic Group ◽  
Beta Oxidation ◽  
The Tca Cycle ◽  
13C Nuclear Magnetic Resonance ◽  
Myocardial Substrate

The effects of streptozotocin-induced diabetes on myocardial substrate oxidation and contractile function were investigated using 13C nuclear magnetic resonance (NMR) spectroscopy. To determine the consequences of diabetes on glucose oxidation, hearts were perfused with [1–13C]glucose (11 mM) alone as well as in the presence of insulin (to stimulate glucose transport) and dichloroacetate (to stimulate pyruvate dehydrogenase). The contribution of glucose to the tricarboxylic acid (TCA) cycle was significantly decreased in hearts from diabetic animals compared with controls, with glucose alone and with insulin; however, the addition of dichloroacetate significantly increased the contribution of glucose to the TCA cycle. Contractile function in hearts from diabetic animals was significantly depressed with glucose as the sole substrate, regardless of the presence of insulin or dichloroacetate (P < 0.0005). To determine whether diabetes had any direct effects on beta-oxidation and the TCA cycle, hearts were perfused with glucose (11 mM) plus [6-13C]hexanoate (0.5 mM) as substrates. In control hearts, with glucose plus hexanoate as substrates, hexanoate contributed 98.9 +/- 2% of the substrate entering the TCA cycle; this was significantly decreased to 90.7 +/- 0.6% in the diabetic group (P < 0.02). The addition of hexanoate to the perfusate resulted in a significant increase in peak systolic pressure in the diabetic group (P < 0.001) such that contractile function was indistinguishable from controls.

scholarly journals Bedaquiline reprograms central metabolism to reveal glycolytic vulnerability in Mycobacterium tuberculosis

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jared S. Mackenzie ◽  
Dirk A. Lamprecht ◽  
Rukaya Asmal ◽  
John H. Adamson ◽  
Khushboo Borah ◽  
...  
Keyword(s):  
Cell Death ◽  
Mycobacterium Tuberculosis ◽  
Metabolic Flux ◽  
Tca Cycle ◽  
Central Carbon Metabolism ◽  
Atp Production ◽  
Isotopomer Analysis ◽  
Metabolic Mechanism ◽  
Substantial Interest ◽  
Insight Into

AbstractThe approval of bedaquiline (BDQ) for the treatment of tuberculosis has generated substantial interest in inhibiting energy metabolism as a therapeutic paradigm. However, it is not known precisely how BDQ triggers cell death in Mycobacterium tuberculosis (Mtb). Using 13C isotopomer analysis, we show that BDQ-treated Mtb redirects central carbon metabolism to induce a metabolically vulnerable state susceptible to genetic disruption of glycolysis and gluconeogenesis. Metabolic flux profiles indicate that BDQ-treated Mtb is dependent on glycolysis for ATP production, operates a bifurcated TCA cycle by increasing flux through the glyoxylate shunt, and requires enzymes of the anaplerotic node and methylcitrate cycle. Targeting oxidative phosphorylation (OXPHOS) with BDQ and simultaneously inhibiting substrate level phosphorylation via genetic disruption of glycolysis leads to rapid sterilization. Our findings provide insight into the metabolic mechanism of BDQ-induced cell death and establish a paradigm for the development of combination therapies that target OXPHOS and glycolysis.

scholarly journals Rescue of TCA Cycle Dysfunction for Cancer Therapy

2019 ◽  
Vol 8 (12) ◽  
pp. 2161 ◽  
Author(s):  
Jubert Marquez ◽  
Jessa Flores ◽  
Amy Hyein Kim ◽  
Bayalagmaa Nyamaa ◽  
Anh Thi Tuyet Nguyen ◽  
...  
Keyword(s):  
Tca Cycle ◽  
Mitochondrial Enzymes ◽  
Mitochondrial Enzyme ◽  
Therapeutic Approaches ◽  
Atp Production ◽  
Tca Cycle Enzymes ◽  
Subcellular Organelle ◽  
The Tca Cycle ◽  
Transport Chain ◽  
Cancer Types

Mitochondrion, a maternally hereditary, subcellular organelle, is the site of the tricarboxylic acid (TCA) cycle, electron transport chain (ETC), and oxidative phosphorylation (OXPHOS)—the basic processes of ATP production. Mitochondrial function plays a pivotal role in the development and pathology of different cancers. Disruption in its activity, like mutations in its TCA cycle enzymes, leads to physiological imbalances and metabolic shifts of the cell, which contributes to the progression of cancer. In this review, we explored the different significant mutations in the mitochondrial enzymes participating in the TCA cycle and the diseases, especially cancer types, that these malfunctions are closely associated with. In addition, this paper also discussed the different therapeutic approaches which are currently being developed to address these diseases caused by mitochondrial enzyme malfunction.

Glucose alleviates ammonia-induced inhibition of short-chain fatty acid metabolism in rat colonic epithelial cells

2003 ◽  
Vol 285 (1) ◽  
pp. G105-G114 ◽  
Author(s):  
John D. Cremin ◽  
Mark D. Fitch ◽  
Sharon E. Fleming
Keyword(s):  
Fatty Acid ◽  
Epithelial Cells ◽  
Short Chain Fatty Acid ◽  
Ketone Bodies ◽  
Tca Cycle ◽  
Chain Fatty Acid ◽  
Short Chain ◽  
Colonic Epithelial Cells ◽  
The Tca Cycle

Ammonia decreased metabolism by rat colonic epithelial cells of butyrate and acetate to CO2 and ketones but increased oxidation of glucose and glutamine. Ammonia decreased cellular concentrations of oxaloacetate for all substrates evaluated. The extent to which butyrate carbon was oxidized to CO2 after entering the tricarboxylic acid (TCA) cycle was not significantly influenced by ammonia, suggesting there was no major shift toward efflux of carbon from the TCA cycle. Ammonia reduced entry of butyrate carbon into the TCA cycle, and the proportion of CoA esterified with acetate and butyrate correlated positively with the production of CO2 and ketone bodies. Also, ammonia reduced oxidation of propionate but had no effect on oxidation of 3-hydroxybutyrate. Inclusion of glucose, lactate, or glutamine with butyrate and acetate counteracted the ability of ammonia to decrease their oxidation. In rat colonocytes, it appears that ammonia suppresses short-chain fatty acid (SCFA) oxidation by inhibiting a step before or during their activation. This inhibition is alleviated by glucose and other energy-generating compounds. These results suggest that ammonia may only affect SCFA metabolism in vivo when glucose availability is compromised.

Sign in / Sign up

Export Citation Format

Share Document