scholarly journals Triidothyronine and epinephrine rapidly modify myocardial substrate selection: a 13C isotopomer analysis

2001 ◽  
Vol 281 (5) ◽  
pp. E983-E990 ◽  
Author(s):  
Julia J. Krueger ◽  
Xue-Han Ning ◽  
Barisa M. Argo ◽  
Outi Hyyti ◽  
Michael A. Portman
Keyword(s):  
Direct Action ◽  
Tricarboxylic Acid Cycle ◽  
Substrate Selection ◽  
Acetoacetic Acid ◽  
Rat Hearts ◽  
Isotopomer Analysis ◽  
Myocardial Substrate ◽  
13C Isotopomer Analysis ◽  
High Work ◽  
C Nmr

Triiodothyronine (T3) exerts direct action on myocardial oxygen consumption (MV˙o 2), although its immediate effects on substrate metabolism have not been elucidated. The hypothesis, that T3 regulates substrate selection and flux, was tested in isovolumic rat hearts under four conditions: control, T3 (10 nM), epinephrine (Epi), and T3 and Epi (TE). Hearts were perfused with [1,3-13C]acetoacetic acid (AA, 0.17 mM),l-[3-13C]lactic acid (LAC, 1.2 mM), U-13C-labeled long-chain free fatty acids (FFA, 0.35 mM), and unlabeled d-glucose (5.5 mM) for 30 min. Fractional acetyl-CoA contribution to the tricarboxylic acid cycle (Fc) per substrate was determined using 13C NMR and isotopomer analysis. Oxidative fluxes were calculated using Fc, the respiratory quotient, and MV˙o 2. T3increased ( P < 0.05) FcFFA, decreased FcLAC, and increased absolute FFA oxidation from 0.58 ± 0.03 to 0.68 ± 0.03 μmol · min−1 · g dry wt−1( P < 0.05). Epi decreased FcFFA and FcAA, although FFA flux increased from 0.58 ± 0.03 to 0.75 ± 0.09 μmol · min−1 · g dry wt−1. T3 moderated the change in FcFFA induced by Epi. In summary, T3 exerts direct action on substrate pathways and enhances FFA selection and oxidation, although the Epi effect dominates at a high work state.

Effects and metabolism of fumarate in the perfused rat heart. A 13C mass isotopomer study

1997 ◽  
Vol 272 (1) ◽  
pp. E74-E82 ◽  
Author(s):  
A. Laplante ◽  
G. Vincent ◽  
M. Poirier ◽  
C. Des Rosiers
Keyword(s):  
Contractile Function ◽  
Gas Chromatography Mass Spectrometry ◽  
Perfused Rat Heart ◽  
Relative Contribution ◽  
Rat Hearts ◽  
Isotopomer Analysis ◽  
Cardioprotective Effects ◽  
Cellular Necrosis ◽  
13C Isotopomer Analysis ◽  
Reductive Pathway

The cardioprotective effects of fumarate have been linked to its metabolism to succinate through both oxidative and reductive pathways. To date, the relative contribution of these pathways is a subject of controversy. To address this question, we designed a protocol with 13C substrates and took advantage of 13C isotopomer analysis by gas chromatography-mass spectrometry. Rat hearts were perfused with 11 mM glucose, 1 mM lactate, 0.2 mM pyruvate, 0.2 mM [1-13C]octanoate, and 0.04 or 0.4 mM [U-13C4]fumarate. On reoxygenation after 40 min of severe hypoxia, hearts perfused with 0.4 mM fumarate showed a better recovery of contractile function and released less lactate dehydrogenase (an index of cellular necrosis) than those perfused with 0.04 mM fumarate. The 13C data showed that, in hypoxic hearts, fumarate conversion to succinate occurred only through reduction, although it accounted for only 16% of total succinate release. Most of the succinate was formed through the oxidation of alpha-ketoglutarate or its precursors (50 +/- 5%) and by another yet-unidentified pathway (34 +/- 4%). These data show that, in a model of hypoxia-reoxygenation, the cardioprotective effects of fumarate were associated with its predominant metabolism to succinate through the reductive pathway.

A critical perspective of the use of 13C-isotopomer analysis by GCMS and NMR as applied to cardiac metabolism

2004 ◽  
Vol 6 (1) ◽  
pp. 44-58 ◽  
Author(s):  
Christine Des Rosiers ◽  
Steven Lloyd ◽  
Blandine Comte ◽  
John C Chatham
Keyword(s):  
Cardiac Metabolism ◽  
Critical Perspective ◽  
Isotopomer Analysis ◽  
13C Isotopomer Analysis

13C isotopomer model for estimation of anaplerotic substrate oxidation via acetyl-CoA

1996 ◽  
Vol 271 (4) ◽  
pp. E788-E799 ◽  
Author(s):  
F. M. Jeffrey ◽  
C. J. Storey ◽  
A. D. Sherry ◽  
C. R. Malloy
Keyword(s):  
Biochemical Analysis ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acetyl Coa ◽  
Acid Cycle ◽  
Propionate Metabolism ◽  
13C Nuclear Magnetic Resonance ◽  
Isotopomer Analysis ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Anaplerotic Pathway

A previous model using 13C nuclear magnetic resonance isotopomer analysis provided for direct measurement of the oxidation of 13C-enriched substrates in the tricarboxylic acid cycle and/or their entry via anaplerotic pathways. This model did not allow for recycling of labeled metabolites from tricarboxylic acid cycle intermediates into the acetyl-CoA pool. An extension of this model is now presented that incorporates carbon flow from oxaloacetate or malate to acetyl-CoA. This model was examined using propionate metabolism in the heart, in which previous observations indicated that all of the propionate consumed was oxidized to CO2 and water. Application of the new isotopomer model shows that 2 mM [3-13C]propionate entered the tricarboxylic acid cycle as succinyl-CoA (an anaplerotic pathway) at a rate equal to 52% of tricarboxylic acid cycle turnover and that all of this carbon entered the acetyl-CoA pool and was oxidized. This was verified using standard biochemical analysis; from the rate (mumol.min-1.g dry wt-1) of propionate uptake (4.0 +/- 0.7), the estimated oxygen consumption (24.8 +/- 5) matched that experimentally determined (24.4 +/- 3).

Impact of 1 wk of diabetes on the regulation of myocardial carbohydrate and fatty acid oxidation

1999 ◽  
Vol 277 (2) ◽  
pp. E342-E351 ◽  
Author(s):  
John C. Chatham ◽  
Zhi-Ping Gao ◽  
John R. Forder
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Fold Increase ◽  
Diabetic Rats ◽  
Diabetic Group ◽  
Acid Oxidation ◽  
Oxidation Rates ◽  
Tissue Extracts ◽  
Isotopomer Analysis ◽  
C Nmr

The aim of this study was to investigate the effect of increasing exogenous palmitate concentration on carbohydrate and palmitate oxidation in hearts from control and 1-wk diabetic rats. Hearts were perfused with glucose, [3-13C]lactate, and [U-13C]palmitate. Substrate oxidation rates were determined by combining13C-NMR glutamate isotopomer analysis of tissue extracts with measurements of oxygen consumption. Carbohydrate oxidation was markedly depressed after diabetes in the presence of low (0.1 mM) but not high (1.0 mM) palmitate concentration. Increasing exogenous palmitate concentration 10-fold resulted in a 7-fold increase in the contribution of palmitate to energy production in controls but only a 30% increase in the diabetic group. Consequently, at 0.1 mM palmitate, the rate of fatty acid oxidation was higher in the diabetic group than in controls; however, at 1.0 mM fatty acid oxidation, it was significantly depressed. Therefore, after 1 wk of diabetes, the major differences in carbohydrate and fatty acid metabolism occur primarily at low rather than high exogenous palmitate concentration.

Thyroid hormone controls myocardial substrate metabolism through nuclear receptor-mediated and rapid posttranscriptional mechanisms

2006 ◽  
Vol 290 (2) ◽  
pp. E372-E379 ◽  
Author(s):  
Outi M. Hyyti ◽  
Xue-Han Ning ◽  
Norman E. Buroker ◽  
Ming Ge ◽  
Michael A. Portman
Keyword(s):  
Thyroid Hormone ◽  
Cardiac Metabolism ◽  
Pyruvate Dehydrogenase Kinase ◽  
Isolated Hearts ◽  
Myocardial Substrate ◽  
Carnitine Palmitoyltransferase I ◽  
Rapid Modulation ◽  
Cpt I ◽  
The Individual ◽  
C Nmr

Thyroid hormone regulates metabolism through transcriptional and posttranscriptional mechanisms. The integration of these mechanisms in heart is poorly understood. Therefore, we investigated control of substrate flux into the citric acid cycle (CAC) by thyroid hormone using retrogradely perfused isolated hearts ( n = 20) from control (C) and age-matched thyroidectomized rats (T). We determined substrate flux and fractional contributions (Fc) to the CAC by 13C-NMR spectroscopy and isotopomer analyses in hearts perfused with [1,3-13C]acetoacetic acid (0.17 mM), l-[3-13C]lactic acid (LAC, 1.2 mM), [U-13C]long-chain mixed free fatty acids (FFA, 0.35 mM), and unlabeled glucose. Some T hearts were supplied triiodothyronine (T3, 10 nM; TT) for 60 min. Prolonged hypothyroid state reduced myocardial oxygen consumption, although T3 produced no significant change. Hypothyroidism reduced overall CACflux but selectively altered only FFAflux among the individual substrates, though LACflux trended upward. T3 rapidly decreased lactate Fc and flux. 13C labeling of glutamine through glutamate was increased in T with further enhancement in TT. The glutamate-to-glutamine ratio was significantly lower in T and TT. Immunoblots detected a decrease in hypothyroid hearts for muscle carnitine palmitoyltransferase I (CPT I) and a marked increase in pyruvate dehydrogenase kinase (PDK)-2 with no changes in liver CPT I, PDK-4, or hexokinase 2. TT, but not T, displayed elevated glutamine synthetase (GS) expression. These studies showed that T3 regulates cardiac metabolism through integration of several mechanisms, including changes in oxidative enzyme content and rapid modulation of individual substrates fluxes. T3 also moderates forward glutamine flux, possibly by increasing the overall activity of GS.

scholarly journals Propionate stimulates pyruvate oxidation in the presence of acetate

2014 ◽  
Vol 307 (8) ◽  
pp. H1134-H1141 ◽  
Author(s):  
Colin Purmal ◽  
Blanka Kucejova ◽  
A. Dean Sherry ◽  
Shawn C. Burgess ◽  
Craig. R. Malloy ◽  
...  
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Energy Production ◽  
Nmr Spectra ◽  
Heart Tissue ◽  
Viable Myocardium ◽  
Normal Heart ◽  
Alternative Substrate ◽  
Isotopomer Analysis ◽  
Nmr Signals ◽  
C Nmr

Flux through pyruvate dehydrogenase (PDH) in the heart may be reduced by various forms of injury to the myocardium, or by oxidation of alternative substrates in normal heart tissue. It is important to distinguish these two mechanisms because imaging of flux through PDH based on the appearance of hyperpolarized (HP) [13C]bicarbonate derived from HP [1-13C]pyruvate has been proposed as a method for identifying viable myocardium. The efficacy of propionate for increasing PDH flux in the setting of PDH inhibition by an alternative substrate was studied using isotopomer analysis paired with exams using HP [1-13C]pyruvate. Hearts from C57/bl6 mice were supplied with acetate (2 mM) and glucose (8.25 mM). 13C NMR spectra were acquired in a cryogenically cooled probe at 14.1 Tesla. After addition of hyperpolarized [1-13C]pyruvate, 13C NMR signals from lactate, alanine, malate, and aspartate were easily detected, in addition to small signals from bicarbonate and CO2. The addition of propionate (2 mM) increased appearance of HP [13C]bicarbonate >30-fold without change in O2 consumption. Isotopomer analysis of extracts from the freeze-clamped hearts indicated that acetate was the preferred substrate for energy production, glucose contribution to energy production was minimal, and anaplerosis was stimulated in the presence of propionate. Under conditions where production of acetyl-CoA is dominated by the availability of an alternative substrate, acetate, propionate markedly stimulated PDH flux as detected by the appearance of hyperpolarized [13C]bicarbonate from metabolism of hyperpolarized [1-13C]pyruvate.

scholarly journals CBMT-49. OXALOACETATE ALTERS GLUCOSE METABOLISM IN GLIOBLASTOMA: 13C ISOTOPOMER STUDY

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi43-vi44
Author(s):  
Omkar Ijare ◽  
David Conway ◽  
Alan Cash ◽  
David Baskin ◽  
Kumar Pichumani
Keyword(s):  
Glucose Metabolism ◽  
Cancer Cells ◽  
Neuronal Cell ◽  
Tca Cycle ◽  
Positive Effects ◽  
Isotopomer Analysis ◽  
Carboxylation Pathway ◽  
13C Isotopomer Analysis ◽  
Positive Effect

Abstract Anhydrous enol-oxaloacetate (AEO) has demonstrated the ability to enhance neuronal cell bioenergetics and activate brain mitochondrial biogenesis. Since oxaloacetate has demonstrated positive effects on brain bioenergetics in neurodegenerative diseases we have begun to investigate whether AEO may also have a positive effect on the altered cellular metabolism found in cancer cells, particularly Glioblastoma multiforme. The “Warburg effect” describes an abnormal metabolic state in cancer, distinct from normal tissue, in which energy is generated through enhanced conversion of pyruvate to lactate even in the presence of oxygen during glycolysis. Oxaloacetate (OAA) is a key anaplerotic substrate that is required to maintain TCA cycle flux. The role of oxaloacetate supplementation on the energy metabolism is not known in cancer cells. Goal of this study is to investigate the changes in metabolic fluxes in glucose metabolism with and without the presence of OAA in patient-derived GBM cells. We use GC-MS based 13C isotopomer analysis for this study. GBM cells are grown in 15mM glucose containing DMEM medium supplemented with 2mM oxaloacetate for 10 days. 6 hours prior to harvesting, [U-13C]glucose is introduced to the medium. 13C isotopomer analysis of GC-MS data showed that OAA supplementation for 10 days drastically decreased Warburg glycolysis by reducing 13C labeling (M+3) by 19.7% and 48.8% in pyruvate and lactate pools respectively in comparison with cells not treated with OAA. M+3 13C labeled pyruvate entered TCA cycle via acetyl-CoA, where we also observed reduced levels of M+2 13C labeled citrate (20.5%) and glutamate (23.9%) isotopomers. Pyruvate can also enter TCA cycle via pyruvate carboxylation pathway and this activity was also found to be slightly decreased in the OAA treated cells. All the differences were statistically significant. These results indicate that OAA can be used to alter bioenergetics of GBM cells, specifically glucose oxidation.

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.

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