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PubMed1991

The alpha-ketoacid dehydrogenase complexes. Sequence similarity of rat pyruvate dehydrogenase with Escherichia coli and Azotobacter vinelandii alpha-ketoglutarate dehydrogenase.

The pyruvate dehydrogenase complex and the alpha-ketoglutarate dehydrogenase complex are multienzyme complexes consisting of three different enzymes. No significant similarity has been reported among the dehydrogenases which are component enzymes of these complexes, despite the presence of homology among the other component enzymes. Here we isolated cDNAs for the alpha and beta subunits of rat pyruvate dehydrogenase and they exhibited a significant similarity of the amino acid sequences among rat pyruvate dehydrogenase, 2-oxoisovalerate dehydrogenase (which is a dehydrogenase component of branched chain alpha-ketoacid dehydrogenase complex) and alpha-ketoglutarate dehydrogenase, suggesting that they have been derived from a common ancestral dehydrogenase. Our results suggested that the alpha and beta subunits of the pyruvate and 2-oxoisovalerate dehydrogenases have been derived by the cleavage of the alpha-ketoglutarate dehydrogenase. However, we could not find significant homology between rat pyruvate dehydrogenase and Gram-negative bacterial pyruvate dehydrogenase.

Amino Acid Sequence↗
PubMed1982

Purification and properties of the pyruvate dehydrogenase complex from Salmonella typhimurium and formation of hybrids with the enzyme complex from Escherichia coli.

The pyruvate dehydrogenase (Pyruvate:lipoamide oxidoreductase (decarboxylating and acceptor acetylating), EC 1.2.4.1) complex from Salmonella typhimurium was purified, characterized and compared to the enzyme complex from Escherichia coli. No difference could be found in the molecular weights of the native enzyme complexes or in the single polypeptide chains of the enzymes of the two organisms. Values of 100 000, 87 000 and 56 000 were obtained for the polypeptide chains of the pyruvate dehydrogenase, the dihydrolipoamide transacetylase (acetyl-CoA:dihydrolipoamide S-acetyltransferase, EC 2.3.1.12) and the dihydrolipoamide dehydrogenase (NADH:lipoamide oxidoreductase, EC 1.6.4.3) components, respectively. Complete cross-reactivity was found with antibodies directed against the pyruvate dehydrogenase complex from E. coli and electron micrographs of both enzyme complexes reveal identical structures. A high Michaelis constant for pyruvate with a Km = 6 . 10(-4) M and a somewhat weaker cooperativity as compared to the enzyme from E. coli reflect some minor differences, while the binding of the cofactor thiamine diphosphate (Km = 1 . 10(-6) M) is identical for both enzyme complexes. Reassociation to a fully active complex molecule works with equal facility between the pyruvate dehydrogenase component and a dihydrolipoamide transacetylase: dihydrolipoamide dehydrogenase subcomplex from either organism in all possible combinations.

Acetyltransferases↗
PubMed1982

Conformational studies of Escherichia coli pyruvate oxidase.

Pyruvate oxidase (pyruvate:oxygen oxidoreductase (phosphorylating), EC 1.2.3.3) is a peripheral membrane enzyme from Escherichia coli which utilizes the cofactors thiamin pyrophosphate (TPP) and flavin-adenine dinucleotide (FAD) to catalyze the decarboxylation of pyruvate to acetic acid and carbon dioxide. The specific activity of the oxidase is enhanced 25-fold when assayed in the presence of certain lipids and detergents. Previous studies have demonstrated that the affinity of pyruvate oxidase for phospholipids and detergents is substantially increased when the flavin is reduced. In this paper, several techniques are utilized to probe both the nature of the active site and the conformational changes in the protein which are concomitant with flavin reduction and with the binding of lipids to the enzyme. Analysis of the circular dichroism spectrum in the far ultraviolet region indicates that neither the binding of lipid activators to the oxidase nor reduction of the enzyme-bound flavin by pyruvate has a significant effect on the average secondary structure of the enzyme. High-resolution electron microscopy demonstrates that at low enzyme concentrations, i.e., assay conditions, incubation of the reduced flavoprotein in the presence of an amphiphilic activator does not alter the quaternary structure of pyruvate oxidase. The results indicate that the conformational changes in the protein due either to reduction of the flavin or to the binding of lipid activators are localized.

Circular Dichroism↗
PubMed1986

A study of the allosteric kinetics of Phycomyces pyruvate kinase as judged by the effect of L-alanine and fructose 1,6-bisphosphate.

The influence of fructose 1,6-bisphosphate and L-alanine on the kinetics of pyruvate kinase (ATP:pyruvate O2-phosphotransferase, EC 2.7.1.40) from Phycomyces blakesleeanus NRRL 1555 (-) was studied at pH 7.5. By addition of fructose 1,6-bisphosphate the sigmoid kinetics with respect to phosphoenol pyruvate and Mg2+ were abolished and the velocity curves became hyperbolic. In the presence of L-alanine the positive homotropic cooperativity with respect to phosphoenol pyruvate increased with Hill coefficient values close to 4, while the sigmoid kinetics with respect to Mg2+ became hyperbolic. Fructose 1,6-bisphosphate overcomes the inhibition produced by L-alanine, the antagonism between phosphoenol pyruvate and L-alanine also being evident. Inhibition has been found at high Mg2+ concentrations, compatible with the binding of the magnesium ions to an inactive conformational state of the enzyme. The data were analysed on the basis of the two-states concerted-symmetry model of Monod, Wyman and Changeux, and the parameters of the model were calculated. Phosphoenol pyruvate and fructose 1,6-bisphosphate appeared to show exclusive binding to the active conformational state (R), whereas magnesium ions bind preferentially, by a factor of 45, to the R state. L-Alanine binds more readily to the inactive T state of the enzyme.

Alanine↗
PubMed1989

A kinetic study of the pH effect on the allosteric properties of pyruvate kinase from Phycomyces blakesleeanus.

This paper reports the pH-dependence of the allosteric kinetics of Phycomyces blakeseeanus pyruvate kinase with phosphoenol pyruvate and Mg2+ ions in the presence and in the absence of fructose 1,6-bisphosphate (allosteric activator) and L-alanine (allosteric inhibitor). Hydrogen ions increase the affinity of the inhibitory binding sites for phosphoenol pyruvate and Mg2+ ions. Assuming partial conformational states of high and low affinity for inhibitory binding sites, the data presented are in good agreement with the predictions postulated by the two-state concerted-symmetry model of Monod, Wyman, and Changeux. Fructose-1,6-bisphosphate and L-alanine show opposite effects on the interactions of phosphoenol pyruvate and Mg2+ ions with their respective catalytic and inhibitory binding sites. At pH 6.0, the regulation of the Phycomyces pyruvate kinase activity by the concentrations of phosphoenol pyruvate and Mg2+ ions is controlled mainly by L-alanine.

Alanine↗
PubMed1991

Purification and functional characterisation of the pyruvate (monocarboxylate) carrier from baker's yeast mitochondria (Saccharomyces cerevisiae).

Isolated yeast mitochondria were subjected to solubilization by Triton X-114 and the detergent extract was subsequently chromatrographed on dry hydroxyapatite. Purification of the yeast monocarboxylate (pyruvate) carrier was achieved by affinity chromatography on immobilized 2-cyano-4-hydroxycinnamate, as described previously for bovine heart mitochondria (Bolli, R., Nałecz K.A. and Azzi, A. (1989) J. Biol. Chem. 264 18024-18030). The final preparation contained two polypeptides of apparent molecular mass 26 and 50 kDa. The yeast carrier appeared to be less abundant, but more active, than the analogous protein from higher eukaryotes. The carrier was able to catalyse the pyruvate / pyruvate and pyruvate / acetoacetate exchange reactions, both reactions being sensitive to cyanocinnamate and its derivatives, to phenylpyruvate and to mersalyl and p-chloromercuribenzoate. In the pyruvate / acetoacetate exchange reaction (200 mM internal acetoacetate, enzymatic assay), the Km value for external pyruvate was found to be 0.8 mM and the Vmax 135 mumol/min per mg protein. Among other substrates of the yeast carrier, all transported with similar affinity and identical maximal velocity against acetoacetate, we identified 2-oxoisocaproate, 2-oxoisovalerate and 2-oxo-3-methylvalerate. Lactate was not translocated by this carrier with a measurable rate, neither were di- or tricarboxylates.

Animals↗
PubMed1992

Phosphorylation of pyruvate kinase type K is restricted to the dimeric form.

In the absence of glycolytic intermediate, fructose-1,6-bisphosphate, pyruvate kinase type K exists in the dimeric form and is readily phosphorylated, whereas in the same sample and the same conditions pyruvate kinase type M is present as a tetramer and is not phosphorylated. Addition of fructose-1,6-bisphosphate results in the association of dimeric K2 molecules to a tetrameric K4 enzyme as determined by gel filtration and cellulose acetate electrophoresis, with concomitant loss of the capacity of the K isozyme to become phosphorylated. Phosphorylated K2 dimers can also tetramerize, but with a low recovery of the radiolabel, suggesting a fructose-1,6-bisphosphate induced dephosphorylation or selective degradation. The dimeric K isozyme is enzymatically active; inactive K-type monomers can be detected by immunoblot analysis in the absence of fructose-1,6-bisphosphate, but no phosphorylated pyruvate kinase is present in this fraction. The formation of K4 tetramers can not be accomplished by the substrate phosphoenolpyruvate. Fructose-1,6-bisphosphate is an allosteric activator of pyruvate kinase type K and induces hyperbolic saturation curves for phosphoenolpyruvate. In contrast, in the absence of effectors, pyruvate kinase type M exhibits Michaelis-Menten kinetics, but sigmoidal curves can be induced by the amino acid phenylalanine. However, even in the presence of phenylalanine, the M-type maintained its tetrameric configuration and did not serve as a substrate in the phosphorylation reaction. These findings argue for the importance of subunit interaction in the regulation of phosphorylation of pyruvate kinase.

Astrocytoma↗
PubMed1991

Hexose metabolism in pancreatic islets: pyruvate carboxylase activity.

The anaplerotic hypothesis for insulin release postulates that an increased generation of malonyl-CoA, acyl residues and diacylglycerol in nutrient-stimulated pancreatic islets may couple the catabolism of nutrient secretagogues to more distal events in the secretory sequence. In the light of this hypothesis, pyruvate carboxylase activity was measured in rat pancreatic islets using two distinct radioisotopic procedures. The first procedure is based on the conversion of oxalacetate generated from pyruvate to 14C-labelled citrate in the presence of [1-14C]acetyl-CoA and citrate synthase. The second technique involves the conversion of 14C-labelled oxalacetate generated from [1-14C]pyruvate to radioactive aspartate in the presence of L-glutamate and glutamate-oxalacetate transaminase. Pyruvate carboxylase activity amounted to 10 pmol/min per islet, was restricted to mitochondria, displayed a Km for pyruvate close to 0.4 mM, and demonstrated dependency towards ATP (apparent Ka close to 0.1 mM), Mg2+ and acetyl-CoA. It is proposed that pyruvate carboxylase activity accounts for the generation of 14C-labelled amino acids other than alanine in islets exposed to D-[3,4-14C]glucose and participates to the pyruvate/citrate shuttle for the transport of acetyl-CoA out of the mitochondria in nutrient-stimulated islets.

Acetyl Coenzyme A↗
PubMed1982

Purification and properties of pyruvate kinase type M2 from rat lung.

(1) Pyruvate kinase type M2 from rat lung has been purified 840-fold with an overall yield of 20%. The enzyme gave a single band upon SDS-electrophoresis and isoelectrofocusing and had a specific activity of 1340 U/mg protein. The homotetramer of Mr = 224000 and an isoelectric point of pH 5.8 had an amino acid composition closely resembling that of other pyruvate kinase isoenzymes type M2, except that of the chicken liver. The enzyme was crystallized. (2) The enzyme has its pH optimum at pH 6.5. The K0.5 value for phosphoenolpyruvate is 0.26 mM (nH = 1.81) which decreases in the presence of 0.2 mM fructose 1,6-bisphosphate to 0.056 mM (nH = 1.06). 1 microM fructose 1,6-bisphosphate activates the enzyme at 0.1 mM phosphoenolpyruvate half-maximally. The Km value for ADP at 1 mM phosphoenolpyruvate is 0.4 mM. The Km value for other nucleoside diphosphates increases in the order ADP less than GDP less than IDP less than UDP. (3) No evidence for an interconversion of pyruvate kinase type M2 from rat or chicken lung was found. The enzyme was neither a substrate for the cAMP-dependent protein kinase from rabbit muscle nor for the cAMP-independent protein kinase from chicken liver. Since pyruvate kinase type M2 from chicken liver is inactivated by phosphorylation catalyzed by a cAMP-independent protein kinase (Eigenbrodt, E., Abdel-Fattah Mostafa, M. and Schoner, W. (1977) Hoppe-Seyler's Z. Physiol. Chem. 358, 1047-1055) we suggest that the interconvertible form of pyruvate kinase type M2 may represent a separate form of the pyruvate kinase type M2 family.

Amino Acids↗
PubMed1986

Demonstration of a heterogeneous distribution of glycolytic enzymes and of pyruvate kinase isoenzymes types M1 and M2 in unfertilized hen eggs.

The intracellular distribution of the glycolytic enzymes hexokinase, glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase and the pyruvate kinase isoenzymes type M1 and type M2 within unfertilized hen eggs was studied. Most of glycolytic enzyme activities were found in the yolk fraction; 8-24% of total glycolytic enzyme activities were found in the vitelline membrane fraction. However, the specific activities of these enzymes in the vitelline membrane fraction are 19-72-fold higher (U/mg protein) and 45-178-fold more concentrated (U/g wet weight) than in the yolk fraction. The study of intracellular localization of pyruvate kinase isoenzymes shows that the blastodisc, latebra and vitelline membrane contain only pyruvate kinase type M2, whereas pyruvate kinase types M1 and M2 are found in the egg yolk. The exclusive occurrence of pyruvate kinase type M2 in the blastodisc is consistent with the concept that this isoenzyme is involved in the cell proliferation. The heterogeneous distribution of the glycolytic enzymes hexokinase, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase, and the heterogeneous localization of the pyruvate kinase isoenzymes types M1 and M2 indicate that glycolysis is distributed heterogeneously within the unfertilized hen egg cell.

Animals↗
PubMed1995

Purification and properties of the pyruvate kinase isozyme M1 from the pig brain.

There are four pyruvate kinase isozymes in vertebrate tissues, designated as L, M1, M2, and R. Although pyruvate kinases have been purified and characterized from pig liver, muscle, kidney, and heart, the brain isozyme has not. The aim of this work was to purify, characterize and make an isozymic designation for the pig brain pyruvate kinase. Purification was accomplished by chromatography on phosphocellulose, Sephadex G200, and blue-dextran agarose columns. The molecular weight of the native enzyme was determined by sucrose density centrifugation. The degree of purity, and subunit molecular weight were determined by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The isoelectric point was estimated by the rapid isoelectric focusing method in sucrose gradients. The pH optimum, and kinetics in the presence and absence of fructose-1,6-diphosphate were determined spectrophotometrically. The purification scheme used resulted in a 382-fold purification of pig brain pyruvate kinase, and a final specific activity of 191 Units/mg protein. As estimated by scanning of the sodium dodecyl sulfate polyacrylamide gels, the purification scheme also resulted in a preparation that was of at least 98% purity. Pig brain pyruvate kinase has a native molecular weight of approx. 230,000, and a subunit molecular weight of approx. 60,000. The pI was determined to be approximately 8.0, while the pH optimum was estimated at pH 7.4. Fructose-1,6-diphosphate had no effect on either the Km for phospho(enol)pyruvate, or the Vmax of the reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

Pyruvate mitigates oxidative stress during reperfusion of cardioplegia-arrested myocardium.

BACKGROUND: Cardioplegic arrest and reperfusion of the myocardium imposes oxidative stress that could potentially inactivate metabolic enzymes and compromise energy production. This study determined the impact of cardioplegic arrest and reperfusion on activities of several oxidant-sensitive enzymes, and tested whether pyruvate, a natural metabolic fuel and antioxidant, mitigates oxidant stress, protects enzymes, and bolsters myocardial energy state after reperfusion. METHODS: In situ swine hearts were arrested for 60 minutes with 4:1 blood:crystalloid cardioplegia, and then reperfused for 3 minutes with cardioplegia-free blood with or without approximately 12 mM pyruvate. Tissue metabolites and enzyme activities were measured in left ventricular myocardium snap frozen at 45 minutes of arrest and 3 minutes of reperfusion. RESULTS: The 8-isoprostane content, a measure of lipid peroxidation, sharply increased upon reperfusion, coincident with a 70% decline in redox state of the intracellular antioxidant glutathione. Aconitase and glucose 6-phosphate dehydrogenase activities fell during arrest; creatine kinase and phosphofructokinase were inactivated upon reperfusion. Pyruvate suppressed 8-isoprostane formation, maintained glutathione redox state, and enhanced phosphocreatine phosphorylation potential, a measure of myocardial energy state, during reperfusion. Pyruvate reactivated creatine kinase and aconitase, which are at least partially mitochondrial enzymes, but did not protect the cytosolic enzymes glucose 6-phosphate dehydrogenase and phosphofructokinase. CONCLUSIONS: Administration of pyruvate upon reperfusion after cardioplegic arrest mitigates oxidative stress, protects mitochondrial enzymes and increases myocardial energy state. These results support therapeutic application of pyruvate-enhanced reperfusion to prevent cardiac injury after cardioplegic arrest.

Animals↗
PubMed2005

Ethyl pyruvate protects PC12 cells from dopamine-induced apoptosis.

Pyruvate acid can protect cells against oxidative damage. However, its instability limits its usefulness as a therapeutic agent. In this study, we examined the effect of ethyl pyruvate, an aliphatic ester derived from pyruvate acid, on dopamine-induced cytotoxicity in rat pheochromocytoma PC12 cells. The results demonstrated that dopamine induced apoptosis in PC12 cells accompanied with increases of intercellular reactive oxygen species, nuclear translocation of nuclear transcription factor kappa B (NF-kappaB) and expression of p53 and decrease of mitochondrial transmembrane potential. Ethyl pyruvate markedly reduced the dopamine-induced production of reactive oxygen species, nuclear translocation of NF-kappaB, upregulation of p53, loss of mitochondrial transmembrane potential and apoptosis in PC12 cells. The results suggested that ethyl pyruvate might protect PC12 cells against dopamine by suppressing intercellular oxidative stress and modulating key signal pathways of apoptosis, and that ethyl pyruvate might be used as a potential therapeutic agent for Parkinson's disease.

Acetylcysteine↗
PubMed2004

The PEP-pyruvate-oxaloacetate node as the switch point for carbon flux distribution in bacteria.

In many organisms, metabolite interconversion at the phosphoenolpyruvate (PEP)-pyruvate-oxaloacetate node involves a structurally entangled set of reactions that interconnects the major pathways of carbon metabolism and thus, is responsible for the distribution of the carbon flux among catabolism, anabolism and energy supply of the cell. While sugar catabolism proceeds mainly via oxidative or non-oxidative decarboxylation of pyruvate to acetyl-CoA, anaplerosis and the initial steps of gluconeogenesis are accomplished by C3- (PEP- and/or pyruvate-) carboxylation and C4- (oxaloacetate- and/or malate-) decarboxylation, respectively. In contrast to the relatively uniform central metabolic pathways in bacteria, the set of enzymes at the PEP-pyruvate-oxaloacetate node represents a surprising diversity of reactions. Variable combinations are used in different bacteria and the question of the significance of all these reactions for growth and for biotechnological fermentation processes arises. This review summarizes what is known about the enzymes and the metabolic fluxes at the PEP-pyruvate-oxaloacetate node in bacteria, with a particular focus on the C3-carboxylation and C4-decarboxylation reactions in Escherichia coli, Bacillus subtilis and Corynebacterium glutamicum. We discuss the activities of the enzymes, their regulation and their specific contribution to growth under a given condition or to biotechnological metabolite production. The present knowledge unequivocally reveals the PEP-pyruvate-oxaloacetate nodes of bacteria to be a fascinating target of metabolic engineering in order to achieve optimized metabolite production.

Bacteria↗
PubMed2005

Ethyl pyruvate enhances ATP levels, reduces oxidative stress and preserves cardiac function in a rat model of off-pump coronary bypass.

BACKGROUND: Off-pump coronary artery bypass grafting is associated with transient periods of myocardial ischemia during revascularization resulting in myocardial contractile dysfunction and oxidative injury. The purpose of this study was to investigate the efficacy of ethyl pyruvate as a myocardial protective agent in a rat model of off-pump coronary artery bypass grafting associated with transient myocardial dysfunction without infarction. METHODS: Wistar rats were subjected to transient ischemia via 10 min occlusion of the LAD coronary artery followed by 10 min of reperfusion. Animals received an IV bolus of Ringer's solution as a control (n=10) or Ringer's ethyl pyruvate (n=10) immediately before the initiation of ischemia and reperfusion. Myocardial ATP and lipid peroxidation levels were quantified for an estimation of energetics and oxidative stress, respectively. In vivo cardiac function was assessed throughout the ischemia and reperfusion periods. RESULTS: Ethyl pyruvate significantly increased myocardial ATP levels compared to controls (2650+/-759 nmol/g versus 892+/-276 nmol/g, p=0.04). Myocardial oxidative stress was significantly reduced in animals treated with ethyl pyruvate compared to controls (70.4+/-2.6 nmol/g versus 81.8+/-2.4 nmol/g, p=0.04). dP/dt max and cardiac output were significantly greater in the ethyl pyruvate group compared to controls during ischemia and reperfusion. CONCLUSIONS: Ethyl pyruvate enhances myocardial ATP levels, reduces oxidative stress, and preserves myocardial function in a model of transient ischemia/reperfusion injury not subject to myocardial infarction.

Adenosine Triphosphate↗
PubMed2004

Pyruvate formation and suppression in recombinant Bacillus megaterium cultivation.

A recombinant Bacillus megaterium strain showed the ability to secrete large amounts of pyruvate (up to 27.8 gl( -1)) for growth rates larger than 0.15 h(-1). Cultivation below this growth rate avoids pyruvate formation while minimizing acetate and succinate production. Using exponential feeding, final biomass concentrations of up to 80 g l(-1) were achieved. Overall molar yields for the experiments with pyruvate formation were as high as 0.79 mol mol(-1). Pyruvate formation was caused by the discrepancy between glycolytic and pyruvate dehydrogenase reaction/tricarboxylic acid cycle capacities during glucose excess. High pyruvate resulted in deceleration and subsequent cessation of growth. In addition, this inhibitory effect is likely associated with the phoshoenolpyruvate:glucose phosphotransferase system used by B. megaterium as the main importer for glucose.

Bacillus megaterium↗
PubMed2005

Pyruvate improves cardiac electromechanical and metabolic recovery from cardiopulmonary arrest and resuscitation.

Severe depletion of myocardial energy and antioxidant resources during cardiac arrest culminates in electromechanical dysfunction following recovery of spontaneous circulation (ROSC). A metabolic fuel and natural antioxidant, pyruvate augments myocardial energy and antioxidant redox states in parallel with its enhancement of contractile performance of stunned and oxidant-challenged hearts. This study tested whether pyruvate improves post-arrest cardiac function and metabolism. Beagles were subjected to 5 min cardiac arrest and 5 min open-chest cardiac compression (OCCC: 80 compressions min(-1); aortic pressure 60-70 mmHg), then epicardial dc countershocks (5-10 J) were applied to restore sinus rhythm. Pyruvate was infused i.v. throughout OCCC and the first 25 min ROSC to a steady-state arterial concentration of 3.6+/-0.2 mM. Control experiments received NaCl infusions. Phosphocreatine phosphorylation potential (approximately PCr) and glutathione/glutathione disulfide ratio (GSH/GSSG), measured in snap-frozen left ventricle, indexed energy and antioxidant redox states, respectively. In control experiments, left ventricular pressure development, dP/dt and carotid flow initially recovered upon defibrillation, but then fell 40-50% by 3 h ROSC. ST segment displacement in lead II ECG persisted throughout ROSC. Approximately PCr collapsed and GSH/GSSG fell 61% during arrest. Both variables recovered partially during OCCC and completely during ROSC. Pyruvate temporarily increased approximately PCr and GSH/GSSG during OCCC and the first 25 min ROSC and enhanced pressure development, dP/dt and carotid flow at 15-25 min ROSC. Contractile function stabilized and ECG normalized at 2-3 h ROSC, despite post-infusion pyruvate clearance and waning of its metabolic benefits. In conclusion, intravenous pyruvate therapy increases energy reserves and antioxidant defenses of resuscitated myocardium. These temporary metabolic improvements support post-arrest recovery of cardiac electromechanical performance.

Analysis of Variance↗
PubMed2003

Enhanced energy metabolism during cold hypoxic organ preservation: studies on rat liver after pyruvate supplementation.

Previous studies have indicated that pyruvate is able to reduce ischaemia/reperfusion (I/R) injury in a variety of tissues, but a full understanding of the effects is lacking. In this current preliminary study, magnetic resonance spectroscopy (MRS) was used to investigate the biochemical effects of differing concentrations of pyruvate (3 and 15mM) on liver metabolism during the cold hypoxic preservation period itself, in order to gain insight into possible mechanisms. Hepatic lactate, alanine, and succinate levels were increased in livers preserved with 15mM pyruvate added to the University of Wisconsin (UW) solution and were generally elevated (but to a lesser degree) in livers flushed with 3mM pyruvate, compared to those cold stored in UW alone. Further, from enzymatic assays of adenine nucleotides, 15mM levels of pyruvate were found to maintain higher ATP levels during short periods (up to 4h) of cold hypoxic storage than in UW stored livers, whilst energy charge ratios (after 4 and 24h) were also higher (P<0.01 in each case). This may arise from enhanced glycolysis secondary to an improved redox status in the pyruvate-treated livers, as evident by the increase in the levels of lactate.

Adenosine↗