1
|
Mallet RT, Olivencia-Yurvati AH, Bünger R. Pyruvate enhancement of cardiac performance: Cellular mechanisms and clinical application. Exp Biol Med (Maywood) 2017; 243:198-210. [PMID: 29154687 DOI: 10.1177/1535370217743919] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Cardiac contractile function is adenosine-5'-triphosphate (ATP)-intensive, and the myocardium's high demand for oxygen and energy substrates leaves it acutely vulnerable to interruptions in its blood supply. The myriad cardioprotective properties of the natural intermediary metabolite pyruvate make it a potentially powerful intervention against the complex injury cascade ignited by myocardial ischemia-reperfusion. A readily oxidized metabolic substrate, pyruvate augments myocardial free energy of ATP hydrolysis to a greater extent than the physiological fuels glucose, lactate and fatty acids, particularly when it is provided at supra-physiological plasma concentrations. Pyruvate also exerts antioxidant effects by detoxifying reactive oxygen and nitrogen intermediates, and by increasing nicotinamide adenine dinucleotide phosphate reduced form (NADPH) production to maintain glutathione redox state. These enhancements of free energy and antioxidant defenses combine to augment sarcoplasmic reticular Ca2+ release and re-uptake central to cardiac mechanical performance and to restore β-adrenergic signaling of ischemically stunned myocardium. By minimizing Ca2+ mismanagement and oxidative stress, pyruvate suppresses inflammation in post-ischemic myocardium. Thus, pyruvate administration stabilized cardiac performance, augmented free energy of ATP hydrolysis and glutathione redox systems, and/or quelled inflammation in a porcine model of cardiopulmonary bypass, a canine model of cardiac arrest-resuscitation, and a caprine model of hypovolemia and hindlimb ischemia-reperfusion. Pyruvate's myriad benefits in preclinical models provide the mechanistic framework for its clinical application as metabolic support for myocardium at risk. Phase one trials have demonstrated pyruvate's safety and efficacy for intravenous resuscitation for septic shock, intracoronary infusion for heart failure and as a component of cardioplegia for cardiopulmonary bypass. The favorable outcomes of these trials, which argue for expanded, phase three investigations of pyruvate therapy, mirror findings in isolated, perfused hearts, underscoring the pivotal role of preclinical research in identifying clinical interventions for cardiovascular diseases. Impact statement This article reviews pyruvate's cardioprotective properties as an energy-yielding metabolic fuel, antioxidant and anti-inflammatory agent in mammalian myocardium. Preclinical research has shown these properties make pyruvate a powerful intervention to curb the complex injury cascade ignited by ischemia and reperfusion. In ischemically stunned isolated hearts and in large mammal models of cardiopulmonary bypass, cardiac arrest-resuscitation and hypovolemia, intracoronary pyruvate supports recovery of myocardial contractile function, intracellular Ca2+ homeostasis and free energy of ATP hydrolysis, and its antioxidant actions restore β-adrenergic signaling and suppress inflammation. The first clinical trials of pyruvate for cardiopulmonary bypass, fluid resuscitation and intracoronary intervention for congestive heart failure have been reported. Receiver operating characteristic analyses show remarkable concordance between pyruvate's beneficial functional and metabolic effects in isolated, perfused hearts and in patients recovering from cardiopulmonary bypass in which they received pyruvate- vs. L-lactate-fortified cardioplegia. This research exemplifies the translation of mechanism-oriented preclinical studies to clinical application and outcomes.
Collapse
Affiliation(s)
- Robert T Mallet
- 1 Department of Integrative Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107-2699, USA
| | - Albert H Olivencia-Yurvati
- 1 Department of Integrative Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107-2699, USA.,2 Department of Medical Education, University of North Texas Health Science Center, Fort Worth, TX 76107-2699, USA
| | - Rolf Bünger
- 3 Emeritus Member of the American Physiological Society, McLean, VA 22101, USA
| |
Collapse
|
2
|
Perry RJ, Borders CB, Cline GW, Zhang XM, Alves TC, Petersen KF, Rothman DL, Kibbey RG, Shulman GI. Propionate Increases Hepatic Pyruvate Cycling and Anaplerosis and Alters Mitochondrial Metabolism. J Biol Chem 2016; 291:12161-70. [PMID: 27002151 PMCID: PMC4933266 DOI: 10.1074/jbc.m116.720631] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Indexed: 02/03/2023] Open
Abstract
In mammals, pyruvate kinase (PK) plays a key role in regulating the balance between glycolysis and gluconeogenesis; however, in vivo regulation of PK flux by gluconeogenic hormones and substrates is poorly understood. To this end, we developed a novel NMR-liquid chromatography/tandem-mass spectrometry (LC-MS/MS) method to directly assess pyruvate cycling relative to mitochondrial pyruvate metabolism (VPyr-Cyc/VMito) in vivo using [3-(13)C]lactate as a tracer. Using this approach, VPyr-Cyc/VMito was only 6% in overnight fasted rats. In contrast, when propionate was infused simultaneously at doses previously used as a tracer, it increased VPyr-Cyc/VMito by 20-30-fold, increased hepatic TCA metabolite concentrations 2-3-fold, and increased endogenous glucose production rates by 20-100%. The physiologic stimuli, glucagon and epinephrine, both increased hepatic glucose production, but only glucagon suppressed VPyr-Cyc/VMito These data show that under fasting conditions, when hepatic gluconeogenesis is stimulated, pyruvate recycling is relatively low in liver compared with VMito flux and that liver metabolism, in particular pyruvate cycling, is sensitive to propionate making it an unsuitable tracer to assess hepatic glycolytic, gluconeogenic, and mitochondrial metabolism in vivo.
Collapse
Affiliation(s)
| | | | | | | | | | - Kitt Falk Petersen
- From the Departments of Internal Medicine, The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen DK 1017, Denmark
| | - Douglas L Rothman
- Radiology and Biomedical Imaging, and the Department of Biomedical Engineering, Yale University, New Haven, Connecticut 06519, and
| | - Richard G Kibbey
- From the Departments of Internal Medicine, Cellular and Molecular Physiology, and
| | - Gerald I Shulman
- From the Departments of Internal Medicine, The Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen DK 1017, Denmark Cellular and Molecular Physiology, and the Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06519,
| |
Collapse
|
3
|
Lewis GD, Farrell L, Wood MJ, Martinovic M, Arany Z, Rowe GC, Souza A, Cheng S, McCabe EL, Yang E, Shi X, Deo R, Roth FP, Asnani A, Rhee EP, Systrom DM, Semigran MJ, Vasan RS, Carr SA, Wang TJ, Sabatine MS, Clish CB, Gerszten RE. Metabolic signatures of exercise in human plasma. Sci Transl Med 2010; 2:33ra37. [PMID: 20505214 DOI: 10.1126/scitranslmed.3001006] [Citation(s) in RCA: 297] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Exercise provides numerous salutary effects, but our understanding of how these occur is limited. To gain a clearer picture of exercise-induced metabolic responses, we have developed comprehensive plasma metabolite signatures by using mass spectrometry to measure >200 metabolites before and after exercise. We identified plasma indicators of glycogenolysis (glucose-6-phosphate), tricarboxylic acid cycle span 2 expansion (succinate, malate, and fumarate), and lipolysis (glycerol), as well as modulators of insulin sensitivity (niacinamide) and fatty acid oxidation (pantothenic acid). Metabolites that were highly correlated with fitness parameters were found in subjects undergoing acute exercise testing and marathon running and in 302 subjects from a longitudinal cohort study. Exercise-induced increases in glycerol were strongly related to fitness levels in normal individuals and were attenuated in subjects with myocardial ischemia. A combination of metabolites that increased in plasma in response to exercise (glycerol, niacinamide, glucose-6-phosphate, pantothenate, and succinate) up-regulated the expression of nur77, a transcriptional regulator of glucose utilization and lipid metabolism genes in skeletal muscle in vitro. Plasma metabolic profiles obtained during exercise provide signatures of exercise performance and cardiovascular disease susceptibility, in addition to highlighting molecular pathways that may modulate the salutary effects of exercise.
Collapse
Affiliation(s)
- Gregory D Lewis
- Cardiology Division and Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA 02114, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
4
|
Tejero-Taldo MI, Caffrey JL, Sun J, Mallet RT. Antioxidant properties of pyruvate mediate its potentiation of beta-adrenergic inotropism in stunned myocardium. J Mol Cell Cardiol 1999; 31:1863-72. [PMID: 10525424 DOI: 10.1006/jmcc.1999.1020] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
UNLABELLED This study tested the hypothesis that pyruvate's antioxidant actions, particularly its enhancement of the endogenous glutathione system, mediate its potentiation of beta-adrenergic inotropism in stunned myocardium. Isolated working guinea pig hearts, metabolizing 10 m M glucose and stunned by 45 min of low flow ischemia, were treated with 5 m M pyruvate, 5 m M N-acetylcysteine (NAC) and/or 2 n M isoproterenol beginning 15 min after reperfusion. The antioxidant NAC alone did not increase cardiac power (mJ/min/g wet: 11 +/- 1 in untreated and 15 +/- 2 in NAC treated stunned hearts), but NAC potentiated the increase in power produced by 2 n M isoproterenol (isoproterenol alone: 50+/-10; NAC plus isoproterenol: 133 +/- 24). Addition of NAC doubled cyclic AMP content but lowered cytosolic phosphorylation potential by 32% in isoproterenol-stimulated hearts. Stunning decreased the glutathione antioxidant ratio (GSH/GSSG) by 68%. The antioxidant ratio was completely restored by pyruvate alone or in combination with isoproterenol, but only partially restored by isoproterenol alone. Combining isoproterenol and NAC increased the GSH/GSSG ratio by an additional 36%. The combined treatment of pyruvate and isoproterenol increased the NADPH/NADP(+) ratio almost three-fold, and produced the greatest accumulation of glucose-6-phosphate of any treatment. CONCLUSIONS like pyruvate, the antioxidant NAC potentiated beta-adrenergic inotropism of stunned myocardium. Unlike pyruvate, NAC did not increase cellular energy reserves, thus effectively limiting its potentiation of beta-adrenergic stimulation. Thus, pyruvate's potentiation of beta-adrenergic stimulation in stunned myocardium is most likely the result of the combined effects of its antioxidant and energetic properties.
Collapse
Affiliation(s)
- M I Tejero-Taldo
- Department of Integrative Physiology and Cardiovascular Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, Texas 76107-2699, USA
| | | | | | | |
Collapse
|
5
|
Graham TE, Gibala MJ. Anaplerosis of the tricarboxylic acid cycle in human skeletal muscle during exercise. Magnitude, sources, and potential physiological significance. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1998; 441:271-86. [PMID: 9781333 DOI: 10.1007/978-1-4899-1928-1_25] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
In comparison to cardiac tissue, relatively few data are available regarding the concentrations of tricarboxylic acid cycle intermediates (TCAI) and the potential influence of TCAI pool size on the regulation of cycle flux in mammalian skeletal muscle. However, recent human exercise studies have confirmed the fundamental observation made in electrically-stimulated rodent muscle that moderate to intense contraction results in a net accumulation of TCAI. The increase in TCAI pool size, termed "anaplerosis," appears exponentially related to work intensity, although the relative changes in the individual cycle intermediates differ markedly. While a number of mechanisms could potentially contribute to the increase in TCAI, the reaction catalyzed by alanine aminotransferase appears primarily responsible for anaplerosis at the onset of exercise in humans. The expansion of the TCAI pool has been suggested to be important for aerobic energy provision, and various theories have been proposed which link the total concentration of TCAI with the capacity for TCA cycle flux during exercise. However, despite the recent advances which have been made with regard to the magnitude and potential source of TCAI expansion in humans, our understanding of the physiological significance of anaplerosis is limited. Indeed, it remains speculative whether the increase in TCAI pool size represents an important regulatory signal or is simply a consequence of the huge increase in metabolic flux which occurs during exercise.
Collapse
Affiliation(s)
- T E Graham
- Department of Human Biology and Nutritional Sciences, University of Guelph, Ontario, Canada
| | | |
Collapse
|
6
|
Gibala MJ, MacLean DA, Graham TE, Saltin B. Tricarboxylic acid cycle intermediate pool size and estimated cycle flux in human muscle during exercise. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:E235-42. [PMID: 9688624 DOI: 10.1152/ajpendo.1998.275.2.e235] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We examined the relationship between tricarboxylic acid (TCA) cycle intermediate (TCAI) pool size, TCA cycle flux (calculated from leg O2 uptake), and pyruvate dehydrogenase activity (PDHa) in human skeletal muscle. Six males performed moderate leg extensor exercise for 10 min, followed immediately by intense exercise until exhaustion (3.8 +/- 0.5 min). The sum of seven measured TCAI (SigmaTCAI) increased (P </= 0.05) from 1.39 +/- 0.11 at rest to 2. 88 +/- 0.31 after 10 min and to 5.38 +/- 0.31 mmol/kg dry wt at exhaustion. TCA cycle flux increased approximately 70-fold during submaximal exercise and was approximately 100-fold higher than rest at exhaustion. PDHa corresponded to 77 and 90% of TCA cycle flux during submaximal and maximal exercise, respectively. The present data demonstrate that a tremendous increase in TCA cycle flux can occur in skeletal muscle despite a relatively small change in TCAI pool size. It is suggested that the increase in SigmaTCAI during exercise may primarily reflect an imbalance between the rate of pyruvate production and its rate of oxidation in the TCA cycle.
Collapse
Affiliation(s)
- M J Gibala
- Copenhagen Muscle Research Centre, Rigshospitalet, DK-2200 Copenhagen N, Denmark
| | | | | | | |
Collapse
|
7
|
Fischer Y, Böttcher U, Eblenkamp M, Thomas J, Jüngling E, Rösen P, Kammermeier H. Glucose transport and glucose transporter GLUT4 are regulated by product(s) of intermediary metabolism in cardiomyocytes. Biochem J 1997; 321 ( Pt 3):629-38. [PMID: 9032447 PMCID: PMC1218116 DOI: 10.1042/bj3210629] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Alternative substrates of energy metabolism are thought to contribute to the impairment of heart and muscle glucose utilization in insulin-resistant states. We have investigated the acute effects of substrates in isolated rat cardiomyocytes. Exposure to lactate, pyruvate, propionate, acetate, palmitate, beta-hydroxybutyrate or alpha-oxoglutarate led to the depression of glucose transport by up to 50%, with lactate, pyruvate and propionate being the most potent agents. The percentage inhibition was greater in cardiomyocytes in which glucose transport was stimulated with the alpha-adrenergic agonist phenylephrine or with a submaximal insulin concentration than in basal or fully insulin-stimulated cells. Cardiomyocytes from fasted or diabetic rats displayed a similar sensitivity to substrates as did cells from control animals. On the other hand, the amination product of pyruvate (alanine), as well as valine and the aminotransferase inhibitors cycloserine and amino-oxyacetate, stimulated glucose transport about 2-fold. In addition, the effect of pyruvate was counteracted by cycloserine. Since reversible transamination reactions are known to affect the pool size of the citrate cycle, the influence of substrates, amino acids and aminotransferase inhibitors on citrate, malate and glutamate content was examined. A significant negative correlation was found between alterations in glucose transport and the levels of citrate (P < 0.01) or malate (P < 0.01), and there was a positive correlation between glucose transport and glutamate levels (P < 0.05). In contrast, there was no correlation with changes in [1-(14)C]pyruvate oxidation or in glucose-6-phosphate levels. Finally, pyruvate decreased the abundance of GLUT4 glucose transporters at the surface of phenylephrine- or insulin-stimulated cells by 34% and 27 % respectively, as determined by using the selective photoaffinity label [3H]ATB-BMPA [[3H]2-N-[4-(1-azi-2,2,2-trifluoroethyl)benzoyl]-1,3-bis-(D-man nos-4-yloxy)propyl-2-amine]. In conclusion, cardiomyocyte glucose transport is subject to counter-regulation by alternative substrates. The glucose transport system appears to be controlled by (a) compound(s) of intermediary metabolism (other than glucose 6-phosphate), but in a different way than pyruvate dehydrogenase. Transport inhibition eventually occurs via a decrease in the amount of glucose transporters in the plasma membrane.
Collapse
Affiliation(s)
- Y Fischer
- Institute of Physiology, Medical Faculty, RWTH Aachen, Federal Republic of Germany
| | | | | | | | | | | | | |
Collapse
|
8
|
Jeffrey FM, Storey CJ, Sherry AD, Malloy CR. 13C isotopomer model for estimation of anaplerotic substrate oxidation via acetyl-CoA. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 271:E788-99. [PMID: 8897869 DOI: 10.1152/ajpendo.1996.271.4.e788] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
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).
Collapse
Affiliation(s)
- F M Jeffrey
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, USA
| | | | | | | |
Collapse
|
9
|
Abstract
Energy has been proposed to play a role in the ability of cells and tissues to defend against oxidative stress, even though the ultimate antioxidant capacity of a tissue is determined by the supply of reducing equivalents. The pathways involved in supplying reducing equivalents in response to an oxidative stress remain unclear, particularly if competing reactions such as ATP synthesis are active. Glutathione (GSH), a major component of cellular antioxidant systems, is maintained in the reduced form by glutathione reductase. Although this enzyme is specific for NADPH, the ability of intact cells, isolated mitochondria (which are a major source of free radicals and contain antioxidant systems independent of the rest of the cell), and whole tissues to supply reducing equivalents and maintain normal levels of GSH appears to involve NADH. This article reviews available data regarding the source and pathways by which reducing equivalents are made available to reduce exogenous oxidants, and suggests energy is not a factor. An improved understanding of the mechanism by which reducing equivalents are supplied by tissues to respond to an oxidative stress may direct future research toward designing strategies for augmenting the ability of tissues to defend themselves against oxidative stress induced by reperfusion or xenobiotics.
Collapse
Affiliation(s)
- J P Kehrer
- Division of Pharmacology/Toxicology, College of Pharmacy, University of Texas at Austin
| | | |
Collapse
|
10
|
el Alaoui-Talibi Z, Bouhaddioni N, Moravec J. Assessment of the cardiostimulant action of propionyl-L-carnitine on chronically volume-overloaded rat hearts. Cardiovasc Drugs Ther 1993; 7:357-63. [PMID: 8364005 DOI: 10.1007/bf00880159] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Chronic volume overload was induced in young rats of Wistar strain by surgical opening of the aorto-caval fistula. Three months later, during in vitro perfusion with exogenous palmitate, left ventricular function and energy turnover (QO2) of hypertrophied hearts were severely depressed. This seemed to be related to impaired long-chain fatty acid utilization, as reflected by decreased 14CO2 production from U-14C-palmitate and decreased tissue levels of L-carnitine. Another group of rats exposed to chronic volume overload was pretreated for 2 weeks before sacrifice with propionyl-L-carnitine (250 mg/kg/day), and the hearts were perfused with 1.2 mM palmitate and 10 mM propionyl-L-carnitine. In this group, both mechanical performance and the oxygen consumption rate were quite comparable to those of untreated controls. On the other hand, tissue levels of L-carnitine were only slightly increased, and the rate of 14CO2 production from U-14C-palmitate was insignificantly improved. This suggests that propionyl-L-carnitine administration promotes the mechanical performance of normoxic volume-overloaded hearts via a mechanism other than improved palmitate utilization. The possibility that propionyl moieties themselves replenish with mitochondrial intermediates of the tricarboxylic cycle (malate, acetyl-CoA) is not excluded.
Collapse
Affiliation(s)
- Z el Alaoui-Talibi
- Laboratoire de'Energétique et de Cardiologie Cellulaire, Faculté de Pharmacie, Université de Bourgogne, Dijon, France
| | | | | |
Collapse
|
11
|
Gallego-Iniesta M, Madero-Madero E, Medina-Puerta MM, Garrido-Pertierra A. Malate enzyme fromPseudomonas putida: Some kinetic properties and function in glucose metabolism. Curr Microbiol 1989. [DOI: 10.1007/bf01575941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
12
|
Sherry AD, Malloy CR, Roby RE, Rajagopal A, Jeffrey FM. Propionate metabolism in the rat heart by 13C n.m.r. spectroscopy. Biochem J 1988; 254:593-8. [PMID: 3178775 PMCID: PMC1135119 DOI: 10.1042/bj2540593] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
High-resolution 13C n.m.r. spectroscopy has been used to examine propionate metabolism in the perfused rat heart. A number of tricarboxylic acid (TCA) cycle intermediates are observable by 13C n.m.r. in hearts perfused with mixtures of pyruvate and propionate. When the enriched 13C-labelled nucleus originates with pyruvate, the resonances of the intermediates appear as multiplets due to formation of multiply-enriched 13C-labelled isotopomers, whereas when the 13C-labelled nucleus originates with propionate, these same intermediates appear as singlets in the 13C spectrum since entry of propionate into the TCA cycle occurs via succinyl-CoA. An analysis of the isotopomer populations in hearts perfused with [3-13C]pyruvate plus unlabelled propionate indicates that about 27% of the total pyruvate pool available to the heart is derived directly from unlabelled propionate. This was substantiated by perfusing a heart for 2 h with [3-13C]propionate as the only available exogenous substrate. Under these conditions, all of the propionate consumed by the heart, as measured by conventional chemical analysis, ultimately entered the oxidative pathway as [2-13C] or [3-13C]pyruvate. This is consistent with entry of propionate into the TCA cycle intermediate pools as succinyl-CoA and concomitant disposal of malate to pyruvate via the malic enzyme. 13C resonances arising from enriched methylmalonate and propionylcarnitine are also detected in hearts perfused with [3-13C] or [1-13C]propionate which suggests that 13C n.m.r. may be useful as a non-invasive probe in vivo of metabolic abnormalities involving the propionate pathway, such as methylmalonic aciduria or propionic acidaemia.
Collapse
Affiliation(s)
- A D Sherry
- Department of Chemistry, University of Texas at Dallas, Richardson 75083-0688
| | | | | | | | | |
Collapse
|
13
|
Schadewaldt P, Rössig M, Staib W. 14CO2 fixation in incubated rat diaphragms. BIOLOGICAL CHEMISTRY HOPPE-SEYLER 1988; 369:181-92. [PMID: 3130842 DOI: 10.1515/bchm3.1988.369.1.181] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The time course (0-60 min) of label incorporation from NaH14 CO3 into citric-acid-cycle intermediates and amino acids was investigated in incubations of isolated rat diaphragms. On the basis of these results, 14CO2 exchange by isocitrate dehydrogenase and 14CO2 fixation by propionyl-CoA carboxylation and pyruvate carboxylation could be estimated. Apparent rates amounted to about 30-40, 2, and 35 nmol/min per g of muscle, respectively. About 90 percent of C4-carbon compounds originating from 14CO2 fixation were subsequently removed by decarboxylation. 2-Cyano-4-hydroxycinnamate, an inhibitor of mitochondrial pyruvate transport, effectively reduced 14CO2 production from [1-14C]pyruvate but did not affect incorporation of radioactive label from NaH14CO3. In cell-free muscle extracts, 14CO2 fixation was demonstrable under assay conditions suitable for NADP -dependent 'malic' enzyme(s). Addition of hydroxymalonate, an inhibitor of the latter enzyme(s), significantly reduced 14CO2 incorporation. The results provide evidence for a continuous cytosolic replenishment and mitochondrial depletion of citric-acid-cycle carbon skeletons in resting skeletal muscle tissue. The functional role of malic (iso)enzyme activities in these processes is discussed.
Collapse
Affiliation(s)
- P Schadewaldt
- Institut für Physiologische Chemie II der Universität Düsseldorf
| | | | | |
Collapse
|
14
|
Swierczyński J, Aleksandrowicz Z, Zelewski L. Stimulatory effect of ADP, ATP, NAD(P) on pyruvate production from malate by uncoupled human placental mitochondria. BIOCHEMICAL MEDICINE AND METABOLIC BIOLOGY 1987; 38:156-64. [PMID: 3675918 DOI: 10.1016/0885-4505(87)90075-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
It has been shown that ADP, ATP, NAD(P), and NAD(P)H significantly stimulate pyruvate production from malate by intact uncoupled human term placental mitochondria. No stimulation by ADP was observed when mitochondria were incubated in the presence of NAD(P) or NAD(P)H or when mitochondrial membrane had been disrupted. Atractyloside and oligomycin were without effect on ADP- and ATP-stimulated pyruvate production. Other dinucleotides tested such as GDP, UDP, and CDP, stimulated pyruvate production only slightly when mitochondria were incubated in the absence of phosphate. The rate of pyruvate production by intact mitochondria is commensurate with partly purified NAD(P)-linked malic enzyme activity as measured by NAD(P) reduction as far as the effects of pH of hydroxymalonate on these both processes is concerned. It is concluded that pyruvate production by intact human placental mitochondria is catalyzed by NAD(P)-linked malic enzyme and that this process is stimulated by ADP and ATP.
Collapse
Affiliation(s)
- J Swierczyński
- Department of Biochemistry, Medical School, Gdańsk, Poland
| | | | | |
Collapse
|
15
|
Sundqvist KE, Heikkilä J, Hassinen IE, Hiltunen JK. Role of NADP+ (corrected)-linked malic enzymes as regulators of the pool size of tricarboxylic acid-cycle intermediates in the perfused rat heart. Biochem J 1987; 243:853-7. [PMID: 3663104 PMCID: PMC1147935 DOI: 10.1042/bj2430853] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cytosolic and mitochondrial concentrations of malate, 2-oxoglutarate, isocitrate and pyruvate in the isolated perfused rat heart were measured by non-aqueous tissue fractionation, taking the NADP-linked isocitrate dehydrogenase as indicator reactions for the free [NADPH]/[NADP+] ratios. The mass-action ratios of NADP-linked malic enzymes (EC 1.1.1.40) were found to be on the side of pyruvate carboxylation by more than one order of magnitude in both the cytosolic and the mitochondrial spaces in hearts perfused with glucose, whereas during propionate perfusion this ratio approached the equilibrium constant (Keq.) of malic enzyme. The results consequently indicate that the NADP-linked malic enzymes cannot be responsible for the feed-out (cataplerotic) reactions from the tricarboxylic acid cycle which occur during glucose perfusion. Only when other anaplerotic fluxes into the cycle are high, as during propionate oxidation, which results in accumulation of tricarboxylic acid-cycle intermediates, is a steady state reached which allows efflux via the malic enzyme.
Collapse
Affiliation(s)
- K E Sundqvist
- Department of Medical Biochemistry, University of Oulu, Finland
| | | | | | | |
Collapse
|
16
|
Klimek J, Swierczyński J, Zelewski L. Inhibition by hydroxymalonate of malate dependent biosynthesis of progesterone in the mitochondrial fraction of human term placenta. JOURNAL OF STEROID BIOCHEMISTRY 1987; 26:161-3. [PMID: 3821103 DOI: 10.1016/0022-4731(87)90045-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
It has been shown that the conversion of cholesterol to progesterone by human term placental mitochondria incubated in the presence of malate or fumarate was inhibited by hydroxymalonate--an inhibitor of malic enzyme. No inhibition was observed when mitochondria were incubated in the presence of citrate or isocitrate. The degree of inhibition by hydroxymalonate of partly purified NAD(P)-linked malic enzyme activity was identical to that of both malate dependent pyruvate and progesterone formation by intact mitochondria. These data strongly support a previous suggestion that malic enzyme plays an important role in the malate dependent progesterone biosynthesis by human placental mitochondria.
Collapse
|
17
|
Pisarenko OI, Solomatina ES, Studneva IM. The role of amino acid catabolism in the formation of the tricarboxylic acid cycle intermediates and ammonia in anoxic rat heart. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 885:154-61. [PMID: 2868758 DOI: 10.1016/0167-4889(86)90083-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Amino acid catabolism, the tricarboxylic acid cycle intermediates and ammonia formation were studied in isolated perfused rat heart under anoxia. The total net anaplerosis due to amino acid degradation in anoxia was equal to that in oxygenation (6.29 and 6.09 mumol/g dry weight per h, respectively) as a result of the increased transamination of glutamic and aspartic acids. During anoxic perfusion, the rate of catabolism of glutamic and aspartic acids was 1.5-times higher than in normoxia, while depletion of branched-chain amino acids, lysine, proline, arginine and methionine, was inhibited. Alanine was the product of excessive degradation of glutamic and aspartic acids. Under anaerobic conditions, in spite of inhibition of amino acid deamination, ammonia formation was increased 2.7-fold as compared to oxygenation. The principal amount of ammonia (96%) was produced at degradation of adenine nucleotides. A 2.5-fold increase in the pool of the tricarboxylic acid cycle intermediates under anoxia was associated mainly with accumulation of succinate. The data suggest that the coupling of alanine- and aspartate amino transferases is a mechanism controlling the tricarboxylic acid cycle pool size in anoxic heart.
Collapse
|
18
|
Swierczyński J, Klimek J, Zelewski L. The role of malic enzyme in the malate dependent biosynthesis of progesterone in the mitochondrial fraction of human term placenta. JOURNAL OF STEROID BIOCHEMISTRY 1985; 22:415-8. [PMID: 3990291 DOI: 10.1016/0022-4731(85)90447-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Mitochondria isolated from human term placenta were able to form citrate from malate as the only added substrate. While mitochondria were incubated in the presence of Mn2+ the citrate formation was stimulated significantly both by NAD+ and NADP+ and was inhibited by hydroxymalonate, arsenite, butylmalonate and rotenone. It is concluded that NAD(P)-linked malic enzyme is involved in the conversion of malate to citrate in these mitochondria. It has also been shown that the conversion of cholesterol to progesterone by human term placental mitochondria incubated in the presence of malate was stimulated by NAD+ and NADP+ and inhibited by arsenite and fluorocitrate. This suggests that the stimulation by malate of progesterone biosynthesis depends not only on the generation of NADPH by NAD(P)-linked malic enzyme, but also on NADPH formed during further metabolism of pyruvate to isocitrate which is in turn efficiently oxidized by NADP+-linked isocitrate dehydrogenase.
Collapse
|
19
|
Skorkowski EF, Biegniewska A, Aleksandrowicz Z, Swierczyński J. Malic enzymes of salmon trout heart mitochondria: separation and some physicochemical properties of NAD-preferring and NADP-specific enzymes. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1985; 80:901-7. [PMID: 3995928 DOI: 10.1016/0305-0491(85)90481-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Mitochondria isolated from the heart of the Baltic salmon trout Salmo trutta contain two distinct malic enzymes. One of these enzymes (NAD-preferring malic enzyme) catalyses the oxidative decarboxylation of malate in the presence of either NAD or NADP. The specific activity with NAD was six times that with NADP as coenzyme. The second enzyme is specific for NADP. These two malic enzymes have been separated by: ion exchange chromatography of DEAE-Sephacel, affinity chromatography on 2',5'ADP-Sepharose 4B, gel filtration on Sephacryl S-300 and polyacrylamide gel electrophoresis. The mol. wts of the two native malic enzymes determined by gel filtration were found to be 280,000 and 190,000 for NAD-preferring and NADP-specific malic enzyme, respectively. Chromatofocusing revealed the isoelectric points of the two enzymes at pH 5.45 and 5.85 for NAD-preferring and NADP-specific malic enzyme, respectively.
Collapse
|
20
|
Sundqvist KE, Peuhkurinen KJ, Hiltunen JK, Hassinen IE. Effect of acetate and octanoate on tricarboxylic acid cycle metabolite disposal during propionate oxidation in the perfused rat heart. BIOCHIMICA ET BIOPHYSICA ACTA 1984; 801:429-36. [PMID: 6487652 DOI: 10.1016/0304-4165(84)90149-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Tricarboxylic acid cycle pool size is determined by anaplerosis and metabolite disposal. The regulation of the latter during propionate metabolism was studied in isolated perfused rat hearts in the light of the characteristics of NADP-linked malic enzyme, which is inhibited by acetyl-CoA. The acetyl-CoA concentration was varied by infusions of acetate and octanoate, and the rate of metabolite disposal was calculated from a metabolic balance sheet compiled from the relevant metabolic fluxes. Propionate addition increased the tricarboxylic acid cycle pool size 4-fold and co-infusion of acetate or octanoate did not change it further. Propionate caused a decrease in the CoA-SH concentration and a 10-fold increase in the propionyl-CoA concentration. A paradoxical increase in the CoA-SH concentration was observed upon co-infusion of acetate in the presence of propionate, an effect probably caused by competitive inhibition of propionate activation. A more pronounced decline in the propionyl-CoA concentration was observed upon the co-infusion of octanoate. In a metabolic steady state, acetate and octanoate reduced propionate disposal only slightly, but did not increase the tricarboxylic acid cycle pool size. The results are in accord with the notion that the tricarboxylic acid pool size is mainly regulated by the anaplerotic mechanisms.
Collapse
|
21
|
Taegtmeyer H. Six blind men explore an elephant: aspects of fuel metabolism and the control of tricarboxylic acid cycle activity in heart muscle. Basic Res Cardiol 1984; 79:322-36. [PMID: 6477383 DOI: 10.1007/bf01908033] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Many aspects of the interactions of energy providing substrates and the operational control of the tricarboxylic acid cycle are still unclear. This statement is well supported by the sometimes conflicting observations in heart muscle. The paper discusses some of the knowns and unknowns of tricarboxylic acid cycle regulation and discusses mechanisms of metabolite accumulation in this tissue. It is concluded that the data available at this time are insufficient to propose a unifying concept.
Collapse
|
22
|
Skorkowski EF, Aleksandrowicz Z, Scisłowski PW, Swierczyński J. Evidence for the role of malic enzyme in the rapid oxidation of malate by cod heart mitochondria. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1984; 77:379-84. [PMID: 6697695 DOI: 10.1016/0305-0491(84)90347-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Mitochondria isolated from the heart of cod (Gadus morrhua callarias) oxidized malate as the only exogenous substrate very rapidly. Pyruvate only slightly increased malate oxidation by these mitochondria. This is in contrast with the mitochondria isolated from rat and rabbit heart which oxidized malate very slowly unless pyruvate was added. Arsenite and hydroxymalonate (an inhibitor of malic enzyme) inhibited the respiration rate of mitochondria isolated from cod heart, when malate was the only exogenous substrate. Inhibition caused by hydroxymalonate was reversed by the addition of pyruvate. In the presence of arsenite, malate was converted to pyruvate by cod heart mitochondria. Cod heart mitochondria incubated in the medium containing Triton X-100 catalyzed the reduction of NADP+ in the presence of L-malate and Mn2+ at relatively high rate (about 160 nmoles NADPH formed/min/mg mitochondrial protein). The oxidative decarboxylation of malate was also taking place when NADP+ was replaced by NAD+ (about 25 nmol NADH formed per min per mg mitochondrial protein). These results suggest that the mitochondria contain both NAD+- and NADP+-linked malic enzymes. These two activities were eluted from DEAE-Sephacel as two independent peaks. It is concluded that malic enzyme activity (presumably both NAD+- and NADP+-linked) is responsible for the rapid oxidation of malate (as the only external substrate) by cod heart mitochondria.
Collapse
|
23
|
Quattrochi LC, Hall LM, Becker GL. alpha-Ketoisocaproate stimulates malate-dependent pyruvate formation in rat heart mitochondria. Biochem Biophys Res Commun 1982; 109:950-7. [PMID: 7159451 DOI: 10.1016/0006-291x(82)92032-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
|
24
|
Peuhkurinen KJ. Accumulation and disposal of tricarboxylic acid cycle intermediates during propionate oxidation in the isolated perfused rat heart. BIOCHIMICA ET BIOPHYSICA ACTA 1982; 721:124-34. [PMID: 7138913 DOI: 10.1016/0167-4889(82)90060-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The role of the metabolite disposal mechanisms in the regulation of the tricarboxylic acid cycle pool size was studied in isolated perfused rat hearts oxidizing 2 mM propionate. Malate and succinate accumulated during the propionate metabolism. A further 118% increase in the malate concentration and 600% increase in the succinate concentration and a slight inhibition of the propionate uptake were observed during a subsequent KCl-induced arrest of the heart metabolizing propionate. When the mechanical activity of the heart was restored, the malate and succinate concentrations returned to the same levels as before the arrest of the heart, but the propionate uptake did not rise significantly. The mean disposal rates of the tricarboxylic acid cycle metabolites during the cardiac arrest and subsequent restoration of the activity were 1.4 and 2.4 mumol/min per g dry weight, respectively during cardiac arrest the malate carbon disposed was almost totally recovered as C3 compounds, whereas after the increase in the ATP-consumption most of it was oxidized. The result show that propionate is oxidized by heart muscle at an appreciable rate but the disposal rate of the tricarboxylic acid cycle intermediates is not tightly regulated by the cellular energy state. Although the metabolite pool size of the tricarboxylic acid cycle responds to change in the ATP consumption, the energy state appears to have a greater effect on the fate of the C3 compounds formed than on the actual rate of C4 compound disposition.
Collapse
|