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PubMed1986

Effect of sepsis on activity of pyruvate dehydrogenase complex in skeletal muscle and liver.

The effect of chronic sepsis on the concentration of active pyruvate dehydrogenase complex has been investigated in liver and skeletal muscle of normal, sterile inflammatory, and chronic septic (small and large abscess) animals. Hyperdynamic sepsis was induced by the intraperitoneal introduction of a rat fecal-agar pellet of known size and bacterial composition (Escherichia coli + Bacteroides fragilis). Total pyruvate dehydrogenase complex activity was not altered in either liver or skeletal muscle in any of the conditions studied. In hepatic tissue, sterile inflammation increased the proportion of active complex 2.5-fold compared with control. The same increase in the concentration of active complex was observed in animals with a small abscess. When the abscess size was increased (large abscess), the concentration of active complex was decreased relative to sterile inflammatory or small abscess septic animals. In contrast to liver, sterile inflammation did not alter the proportion of active complex in skeletal muscle. Sepsis (either small or large septic abscess) resulted in threefold decrease in the concentration of active complex relative to control or sterile inflammatory animals. Changes in the concentration of active complex did not appear to be dependent on the ATP/ADP concentration ratio or tissue pyruvate levels but were consistent with changes in the acetyl-coenzyme A-to-coenzyme A concentration ratio. The mechanism responsible for altered concentration of active complex may be mediated through changes in the activity of the pyruvate dehydrogenase kinase, secondary to alterations in the effector concentration ratios.

Abscess↗
PubMed1985

Compartmented pyruvate in perfused working heart.

Pyruvate compartmentation and lactate dehydrogenase (LDH) were studied in isolated perfused working guinea pig hearts. The mean intracellular pyruvate (Pyr) contents increased with perfusate Pyr (0-2 mM) but varied only slightly with glucose (0-10 mM) and additional insulin (0.04-5 U/l), respectively. With 5-10 mM glucose plus 5 U/l insulin, but not with Pyr or lactate (Lac) as substrates, a near equilibrium between the LDH and the glycerol-3-phosphate dehydrogenase seemed to exist. Evidence for an inhibitory effect of Pyr on the activity of the LDH system of the perfused hearts was not obtained. With [U-14C]glucose as sole substrate, the specific activity of coronary venous Lac was near half that of precursor glucose. 14CO2 production was thus in quantitative agreement with rates of pyruvate oxidation that were determined as glucose uptake minus (Pyr + Lac) release. In contrast, with 0.2 mM [1-14C]Pyr plus 5 mM glucose, the ratio of 14CO2 production to specific activity of Lac overestimated Pyr oxidation judged from myocardial substrate balances and O2 uptake, respectively; here, at least three pools of [14C]HCO-3 and [14C]lac, respectively, were kinetically demonstrable during washout of trace amounts of 14C-labeled Pyr. Evidently, the specific activity of Lac was equivalent to that of mitochondrial oxidized Pyr provided [14C]glucose was the sole or major precursor of cellular pyruvate. However, exogenously applied [1-14C]Pyr of high specific activity seemed to induce intracellular formation of both a highly and lowly labeled Pyr; the latter Pyr compartment did not seem in ready equilibrium with the cell physiologically prevailing highly labeled Pyr pool.

Animals↗
PubMed1996

Impaired pyruvate oxidation but normal glucose uptake in diabetic pig heart during dobutamine-induced work.

We tested the hypothesis that diabetes impairs myocardial glucose uptake and pyruvate oxidation under normal conditions and during a dobutamine-induced increase in work. We also tested the hypothesis that an increase in work would result in a decrease in the levels of malonyl CoA, a potent inhibitor of carnitine palmitoyltransferase I (CPT I). Streptozotocin-diabetic micropigs were compared with a nondiabetic control group (n = 8 per group). Triglyceride emulsion, glucose, and somatostatin were infused into the nondiabetic group to create an acute diabetic-like state. In accord with our hypothesis, malonyl CoA decreased significantly with dobutamine in both groups, providing a possible mechanism for increased fatty acid oxidation through relieved inhibition on CPT I. In the absence of dobutamine, glucose uptake and tracer-measured lactate uptake were decreased by 57 and 80%, respectively, in the diabetic group. Dobutamine infusion resulted in similar increases in cardiac contractility, oxygen consumption, and glucose uptake in both groups despite reductions of 50-65% in GLUT-4 and GLUT-1 protein in the diabetic group. Diabetic animals possessed a defect in myocardial pyruvate oxidation, as reflected in increased lactate production, and depressed lactate uptake and pyruvate dehydrogenase activity under control and dobutamine conditions. In conclusion, the major derangement in carbohydrate metabolism in diabetic myocardium was not in glycolysis but, rather, in pyruvate oxidation.

Acetyl-CoA Carboxylase↗
PubMed2004

Role of pyruvate oxidase in Escherichia coli strains lacking the phosphoenolpyruvate:carbohydrate phosphotransferase system.

We report a study to determine the role of pyruvate oxidase among Escherichia coli isogenic strains with active and inactive phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS). Strain PB11, displaying a specific growth rate (mu) in glucose minimal medium of 0.1 h(-1) is a ptsHI, crr operon deletion derivative of wild-type JM101 (displaying a mu of 0.70 h(-1)). Strain PB12 is a spontaneous mutant obtained from PB11 after selection for its capacity to grow on glucose with a mu of 0.40 h(-1). In minimal medium cultures supplemented with glucose plus acetate, strain JM101 displayed preferential consumption of glucose, whereas strains PB11 and PB12 did not display glucose catabolic repression of acetate consumption. Inactivation of poxB caused a severe reduction in growth rate in strain PB11 when grown in the fermentor with medium containing glucose or glucose plus acetate, whereas under the same conditions poxB(-)derivative strains of JM101 and PB12 were not affected. Relative transcript levels for 29 genes related to poxB transcriptional regulation and central metabolism were determined using RT-PCR. This analysis revealed 2-fold lower transcript levels for genes encoding subunits of the pyruvate dehydrogenase complex (Pdh) in strain PB11 and 4- to 6-fold higher transcript levels for poxB in strains PB11 and PB12, when compared to JM101. In addition, in the PTS(-) strains, upregulation of the poxB transcription factors rpoS, soxS and marA, was detected. The results presented here strongly suggest that AcCoA is mainly synthesized from acetate produced by pyruvate oxidase in strain PB11, whereas in strains JM101 and PB12, AcCoA is synthesized preferentially from pyruvate by Pdh.

Acetic Acid↗
PubMed1981

Pyruvate dehydrogenase complex activity in normal and deficient fibroblasts.

Pyruvate dehydrogenase complex (PDC) activity in human skin fibroblasts appears to be regulated by a phosphorylation-dephosphorylation mechanism, as is the case with other animal cells. The enzyme can be activated by pretreating the cells with dichloroacetate (DCA), an inhibitor of pyruvate dehydrogenase kinase, before they are disrupted for measurement of PDC activity. With such treatment, the activity reaches 5-6 nmol/min per mg of protein at 37 degrees C with fibroblasts from infants. Such values represent an activation of about 5-20-fold over those observed with untreated cells. That this assay, based on [1-(14)C]pyruvate decarboxylation, represents a valid measurement of the overall PDC reaction is shown by the dependence of (14)CO(2) production on the presence of thiamin-PP, coenzyme A (CoA), Mg(++), and NAD(+). Also, it has been shown that acetyl-CoA and (14)CO(2) are formed in a 1:1 ratio. A similar degree of activation of PDC can also be achieved by adding purified pyruvate dehydrogenase phosphatase and high concentrations of Mg(++) and Ca(++), or in some cases by adding the metal ions alone to the cell homogenate after disruption. These results strongly suggest that activation is due to dephosphorylation. Addition of NaF, which inhibits dephosphorylation, leads to almost complete loss of PDC activity. Assays of completely activated PDC were performed on two cell lines originating from patients reported to be deficient in this enzyme (Blass, J. P., J. Avigan, and B. W. Ublendorf. 1970. J. Clin. Invest. 49: 423-432; Blass, J. P., J. D. Schuman, D. S. Young, and E. Ham. 1972. J. Clin. Invest. 51: 1545-1551). Even after activation with DCA, fibroblasts from the patients showed values of only 0.1 and 0.3 nmol/min per mg of protein. A familial study of one of these patients showed that both parents exhibited activity in fully activated cells about half that of normal values, whereas cells from a sibling appeared normal. These results demonstrate the inheritance nature of PDC deficiency, and that the present assay is sufficient to detect the heterozygous carriers of the deficiency. Application of the same procedures to fibroblasts obtained from 16 individuals who were believed to have normal PDC activities showed a range from about 2-2.5 nmol/min per mg protein for adults to 5-6 nmol/min per mg protein for cells from infants.

Acetyl Coenzyme A↗
PubMed1977

Deficiency of dihydrolipoyl dehydrogenase (a component of the pyruvate and alpha-ketoglutarate dehydrogenase complexes): a cause of congenital chronic lactic acidosis in infancy.

A male child died at 7 months of age with progressive neurologic deterioration and persistent metabolic acidosis. Investigations during life showed this child to have elevated blood pyruvate, lactate, and alpha-ketoglutarate as well as elevation of branched chain amino acids and occasional hypoglycemia. Cofactor therapy using either thiamine-HCl (2 g/kg/24 hr) or thiamine tetrahydrofurfuryl disulfide had no measurable effect on the clinical or biochemical status of the patient. Tissue taken postmortem showed normal levels of key gluconeogenic enzymes but a deficiency in the activity of pyruvate dehydrogenase in all tissues tested (liver, brain, kidney, skeletal muscle, and heart). Examination of the individual activities of pyruvate dehydrogenase complex showed pyruvate decarboxylase (E1) to be normal in liver and other tissues. Dihydrolipoyl dehydrogenase (E3), on the other hand, was deficient in all tissues tested. alpha-Ketoglutarate dehydrogenase complex, which depends of E3 for its total activity, was also deficient in all tissues tested. The absence of this enzyme id discussed in relation to the clinical and biochemical status of the patient.

Acidosis↗
PubMed1984

A possible role for potassium and pyruvate in the modulation of sperm motility in the rabbit oviducal isthmus.

Spermatozoa were recovered from the isthmus of the rabbit oviduct at 4 and 11 h post coitum using several defined flushing media. The motility of spermatozoa in the isthmic flushings was subsequently analysed from video recordings. There was little sperm movement in the native isthmic fluid, but vigorous flagellar activity and hyperactivated movement were induced by flushing the isthmus with 0.25 M-sucrose, apparently an effect of dilution. Flushing with a complex culture medium resulted in similar stimulation of sperm movement. When pyruvate was present in the medium, hyperactivated flagellar bending was stimulated, whereas these movements were virtually absent when glucose alone was present. The stimulating effect of dilution was less pronounced when the flushing medium contained 50 mM-potassium. When the isthmus was flushed with media containing 50 mM-K+ and the K+ concentration was lowered to 5 mM during a washing procedure, large-amplitude flagellar movements were sequentially suppressed and restored. The restoration of large-amplitude movements was enhanced when pyruvate was present in the 5 mM-K+ washing medium. These results suggest that alterations in the concentration of both K+ and pyruvate may have a role in regulating the motility of rabbit spermatozoa in the oviducal isthmus, K+ being inhibitory and pyruvate stimulatory.

Animals↗
PubMed1983

Effects of FSH, isoproterenol, and cyclic AMP on the production of lactate and pyruvate by cultured Sertoli cells.

We have examined the hormonal regulation of the secretion of lactate and pyruvate from cultured rat Sertoli cells. FSH and isoproterenol caused 3-6-fold stimulation of lactate and pyruvate secretion, whereas ovine LH, TSH, and prolactin were ineffective. Dibutyryl cyclic AMP (10(-4) M) stimulated the secretion of lactate and pyruvate to the same extent as FSH. Much lower stimulation was observed when Sertoli cells from 43-day old rats were exposed to FSH or isoproterenol. FSH increased lactate secretion in a concentration-dependent manner. The concentration of FSH (NIH-S14) causing half-maximal stimulation of lactate secretion (150 ng/ml) was similar to that causing 50% maximal stimulation of Sertoli cell adenylyl cyclase. Both FSH and isoproterenol caused a time-dependent increase in lactate levels in the incubation medium during the first 6-9 hr after the addition of hormones, after which levels were constant or decreased. Thus, the production of lactate and pyruvate by cultured Sertoli cells is stimulated both by FSH and isoproterenol and these effects are exerted via cyclic AMP.

Animals↗
PubMedDate not supplied

[Effect of insulin and hydrocortisone on the isoenzyme composition of pyruvate kinase in the rabbit kidney].

Alloxan diabetes, starvation of rabbits within one day and administration of hydrocortisone during 5 days did not cause distinct alterations in the total activity of pyruvate kinase in kidney cortex. At the same time pronounced alterations in the isozyme spectra were observed: the L-type activity of pyruvate kinase was decreased and the M2-type of activity was increased. The total activity and the isozyme content of pyruvate kinase were only slightly altered in starvation of rabbits during 3 or 10-16 days and after administration of protamine-Zn-insulin during 3 days. Hydrocortisone caused variable effects on the pyruvate kinase isozymes from kidney cortex, depending on periods of administration.

Animals↗
PubMed1992

In vivo effect of glucocorticoids on the rates of pyruvate utilization and lactate formation by incubated lymphocytes.

Although the immunosuppressive effect of glucocorticoids has been widely reported, the mechanism of action of these hormones on the immune system has not been fully established. In the present study, the effect of glucocorticoids on the rates of pyruvate utilization and lactate production by lymphocytes obtained from rat mesenteric lymph nodes was investigated. Adult rats were injected with dexamethasone (1 mg/kg, ip) daily for 3 days. A stressed group which received a corresponding volume of 0.9% saline and control rats not injected were also included. All treatments were carried out at 17:00 h. Stress or administration of dexamethasone reduced the rate of pyruvate utilization by 50% and 62%, respectively. The hormonal injection increased the rate of lactate production by 57%, whereas the stressed group showed a 2.4-fold increase of the conversion of pyruvate to lactate, as compared to control rats. These findings suggest that glucocorticoids regulate pyruvate metabolism in lymphocytes and that an additional neurohormonal factor released during stress may also participate in the control of lactate production.

Animals↗
PubMed1991

Alcohol and pyruvate cardioplegia. Twenty-four-hour in situ preservation of hamster hearts.

Isolated hamster hearts were first perfused with a normal Krebs-Henseleit medium to demonstrate comparable viability of hearts before perfusing and storing them for 24 hours in one of three solutions. The three solutions were a physiologic saline with pyruvate as the substrate and 4% alcohol to arrest the heart (group 1), a standard cardioplegic solution (group 2), and an alcohol-free physiologic saline with pyruvate as the substrate (group 3). Recovery in terms of rate/pressure product and oxygen consumption after 30 minutes of reperfusion was 81% and 93%, respectively, for group 1, 13% and 32% for group 2, and 70% and 72% for group 3. Percent of physiologic recovery was not related to recovery of adenosine triphosphate. The adenosine triphosphate level returned to approximately 40% control level in all three groups, and in all three groups inorganic phosphate remained approximately 320% over control level after 30 minutes of reperfusion. Phosphocreatine level significantly higher in groups 1 and 3 than in group 2, as a result of improved oxygen consumption. Intracellular pH, determined by phosphorous 31 nuclear magnetic resonance spectroscopy, was physiologic in groups 1 and 3 but alkaline in group 2. This alkalinity may have been caused by leaky membranes. Pyruvate helped preserve mitochondrial function during depressed oxygen delivery, such as was seen during the 24-hour storage period. Four percent alcohol arrested the heart; combined with pyruvate plus alcohol solution were better than a standard cardioplegic solution for maintaining functional capability.

Animals↗
PubMed1990

Pyruvate utilization of rabbit reticulocytes--a compartmental study.

The utilization of [2-14C] pyruvate via the citric acid cycle of rabbit reticulocytes was studied to elucidate the importance of carboxylation- and decarboxylation reactions in this cell type. Unknown flux rates were determined by fitting the observed time-dependent labeling of CO2, alanine, glutamate and aspartate (all carbon atoms and C alpha) to the corresponding set of differential equations. The results reveal a high activity of the shuttle rate between mitochondrial pyruvate and the C4 pool catalysed by the pyruvate carboxylase (v = 19.1 nM/ml cells/min) and the malic enzyme (v = 57.5 mM/ml cells/min) which is comparable with the flux rate within the citrate cycle (v2 = 46.2 nM/ml cells/min). Moreover, our studies provide strong indications for the existence of a pyruvate utilizing metabolic pathway which has not been described so far.

Alanine↗
PubMed1989

Studies on the formation of lactate and pyruvate from glucose in cultured skin fibroblasts: implications for detection of respiratory chain defects.

We investigated the time course of the formation of lactate and pyruvate from glucose in cultured skin fibroblasts from controls, from a patient with a cytochrome c oxidase deficiency and from controls treated with inhibitors of the individual respiratory chain complexes. Fibroblasts from the patient and inhibitor treated fibroblasts produced more lactate and less pyruvate; this resulted in a significant increase in the lactate to pyruvate ratio, reflecting an increased cytosolic NADH/NAD+ redox state. We conclude that measurement of lactate and pyruvate production from glucose in cultured skin fibroblasts can be of value in the diagnosis of inherited diseases of the mitochondrial respiratory chain.

Cells, Cultured↗
PubMed1989

Lactate and pyruvate kinetics after treadmill exercise in patients with intermittent claudication.

Lactate and pyruvate movements in arterial and venous blood during recovery following treadmill exercise in 8 patients with arterial occlusive disease were studied by means of a two-compartment model. Blood lactate and pyruvate concentration curves over the recovery period were found to fit a two-exponential time function including a rapidly increasing and a slowly decreasing component. The velocity constants gamma 2 were dependent on the exercise load. The time of lactate disappearance during recovery decreased with the work load in patients with intermittent claudication. The velocity constant of the arterial blood pyruvate decrease was similar to that of the simultaneously measured lactate indicating that the rate of lactate removal is closely related to that of pyruvate. In conclusion, the use of the model allows to study factors likely to modify the coefficients, such as physical training, therapeutic effects and active recovery.

Adult↗
PubMedDate not supplied

[Effect of pyruvate on metabolic processes in erythrocytes after acute massive blood loss].

It is shown in the in vitro experiments that addition into the incubation medium of 10 mumol pyruvate is accompanied by the inhibition of the lactate dehydrogenase activity. The level of 2.3-biphosphoglycerate, ATP, lactate and hemoglobin increases by 92%, 265%, 93% and 56%, respectively. The acute massive haemorrhage against a background of infusion of 0.065% solution of pyruvate does not evoke a decrease in the hemoglobin level, which is observed after infusion of the physiological solution. The value of hematocrit proved to be higher to some extent. The 2,3-biphosphoglycerate level and the activity of glucoso-6-phosphate dehydrogenase are not changed in comparison with the results of intact rats. The glutathione reductase activity rises by 38%. The lactate level diminishes by 34%. Pyruvate is established to exert a therapeutic effect in acute massive haemorrhage. The survival rate of rats after infusion of pyruvate increases by 65%.

Acute Disease↗
PubMed1988

Pyruvic acid protects against the lethality of sulfide.

The efficacy of pyruvic acid in protecting mice against the lethal effects of sodium sulfide was examined. Pyruvic acid (1 g/kg, i.p.) reduced the mortality of sodium sulfide (100 mg/kg, i.p.) from 100% to 5% when administered 15 min prior to the sulfide. The protective effect of pyruvic acid decreased over time but was still present at 20 min and 30 min, with 40% and 50% mortality, respectively. The lethality of sulfide in larger mice was less than that in smaller mice when the doses were normalized for body weight, but the protection factor of the pyruvic acid, approximately 2.0, was the same for both sizes.

Animals↗
PubMed1986

Comparative study of the effects of pyruvate and CG-120 in preventing experimental oxalate urolithiasis in rats.

Male Wistar-strain rats which had been fed a calcium-oxalate lithogenic diet (a glycolate diet) developed urinary calculi in 4 weeks. Sodium pyruvate or CG-120 (a mixture of citrate salts) had been added to this diet to determine its effect in preventing lithogenicity. Rats in the group fed a pyruvate diet had, however, almost no stones in the urinary system. Rats in the CG-120 group showed results somewhat similar to those in the pyruvate group. Increased urinary citrate excretion was observed in both groups and could be implicated as the main inhibitory factor in stone formation. Therefore, it can be concluded that CG-120 exerts a beneficial effect close to that of pyruvate in preventing calculi formation and that both substances cause a high citrate excretion in urine.

Animals↗
PubMed1983

[3H]biotin-labeled proteins in cultured human skin fibroblasts from patients with pyruvate carboxylase deficiency.

Biotin containing carboxylases in cultured human skin fibroblasts were radioactively labeled by addition of [8,9-3H]biotin to biotin-depleted cell cultures. Three major bands were visualized by fluorography after sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the fibroblast proteins. These bands corresponded to pyruvate carboxylase (Mr = 125,000), the biotin-containing subunit of methyl crotonyl-CoA carboxylase (Mr = 75,000) and the biotin-containing subunit of propionyl-CoA carboxylase (Mr = 73,000) as judged by molecular weight markers, purified carboxylase protein standards, and interaction with monospecific antisera. Four out of 5 cell lines from patients with classical pyruvate carboxylase deficiency (less than 5% of normal activity) labeled with this technique displayed a normal band in the position of pyruvate carboxylase while one cell line showed complete absence of any labeled protein in this area. These results demonstrate heterogeneity in the etiology of pyruvate carboxylase deficiency.

Biotin↗