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Nissim I, Daikhin Y, Nissim I, Luhovyy B, Horyn O, Wehrli SL, Yudkoff M. Agmatine stimulates hepatic fatty acid oxidation: a possible mechanism for up-regulation of ureagenesis. J Biol Chem 2006; 281:8486-96. [PMID: 16452488 DOI: 10.1074/jbc.m506984200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We demonstrated previously in a liver perfusion system that agmatine increases oxygen consumption as well as the synthesis of N-acetylglutamate and urea by an undefined mechanism. In this study our aim was to identify the mechanism(s) by which agmatine up-regulates ureagenesis. We hypothesized that increased oxygen consumption and N-acetylglutamate and urea synthesis are coupled to agmatine-induced stimulation of mitochondrial fatty acid oxidation. We used 13C-labeled fatty acid as a tracer in either a liver perfusion system or isolated mitochondria to monitor fatty acid oxidation and the incorporation of 13C-labeled acetyl-CoA into ketone bodies, tricarboxylic acid cycle intermediates, amino acids, and N-acetylglutamate. With [U-13C16] palmitate in the perfusate, agmatine significantly increased the output of 13C-labeled beta-hydroxybutyrate, acetoacetate, and CO2, indicating stimulated fatty acid oxidation. The stimulation of [U-13C16]palmitate oxidation was accompanied by greater production of urea and a higher 13C enrichment in glutamate, N-acetylglutamate, and aspartate. These observations suggest that agmatine leads to increased incorporation and flux of 13C-labeled acetyl-CoA in the tricarboxylic acid cycle and to increased utilization of 13C-labeled acetyl-CoA for synthesis of N-acetylglutamate. Experiments with isolated mitochondria and 13C-labeled octanoic acid also demonstrated that agmatine increased synthesis of 13C-labeled beta-hydroxybutyrate, acetoacetate, and N-acetylglutamate. The current data document that agmatine stimulates mitochondrial beta-oxidation and suggest a coupling between the stimulation of hepatic beta-oxidation and up-regulation of ureagenesis. This action of agmatine may be mediated via a second messenger such as cAMP, and the effects on ureagenesis and fatty acid oxidation may occur simultaneously and/or independently.
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Affiliation(s)
- Itzhak Nissim
- Children's Hospital of Philadelphia, Division of Child Development, Rehabilitation Medicine, and Metabolic Disease, Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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Barron JT, Sasse MF, Nair A. Effect of angiotensin II on energetics, glucose metabolism and cytosolic NADH/NAD and NADPH/NADP redox in vascular smooth muscle. Mol Cell Biochem 2005; 262:91-9. [PMID: 15532713 DOI: 10.1023/b:mcbi.0000038221.44904.a1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Angiotensin II (AII) is a neurohormone and contractile agonist of vascular smooth muscle that has been shown to be involved in the pathogenesis of vascular disease, which may be partially caused by its effect on oxidant stress. Energy metabolism was examined in pig carotid arteries treated with AII, because the activity of pathways of intermediary metabolism of glucose determines the status of cytosolic NADH/NAD and NADPH/NADP redox, factors which are involved in oxidant stress. Contractile responses to AII were characterized by an increase in isometric force followed by a gradual decline to near-basal levels. Despite contractile activation, no change in glycolysis, lactate production, glucose oxidation, fatty acid oxidation, O2 consumption, glycogen content or high-energy phosphates was detected when compared to resting unstimulated arteries. Paradoxically, total uptake of glucose was inhibited by AII. Treatment with diphenylene iodinium, an inhibitor of NAD(P)H oxidase and superoxide production, reversed the inhibition of glucose uptake and revealed the expected increase in glucose uptake and oxidation upon contractile activation of smooth muscle by AII. The intracellular [lactate]/[pyruvate] ratio was increased, reflecting an increase in cytosolic NADH/NAD redox, whereas NADPH/NADP redox was decreased by AII. No change in NADPH/NADP redox was observed when membrane depolarization with K+ was used as the contractile agent. It is concluded that the pattern of force generation, metabolism and energetics of AII-stimulated contraction are significantly different from that of other contractile agonists. Most notably AII inhibited glucose uptake. NAD(P)H oxidase and/or attendant superoxide may play a role in modulating glucose metabolism. AII induces opposite changes in NADH/NAD redox and NADPH/NADP redox, which may have important consequences for oxidant stress.
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Affiliation(s)
- John T Barron
- Division of Cardiology, Department of Internal Medicine, Rush Medical College, Rush University Medical Center, Chicago, IL, USA.
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Hagopian K, Ramsey JJ, Weindruch R. Krebs cycle enzymes from livers of old mice are differentially regulated by caloric restriction. Exp Gerontol 2004; 39:1145-54. [PMID: 15288689 DOI: 10.1016/j.exger.2004.04.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Revised: 04/21/2004] [Accepted: 04/27/2004] [Indexed: 11/26/2022]
Abstract
Krebs cycle enzyme activities and levels of five metabolites were determined from livers of old mice (30 months) maintained either on control or on long-term caloric restriction (CR) diets (28 months). In CR mice, the cycle was divided into two major blocks, the first containing citrate synthase, aconitase and NAD-dependent isocitrate dehydrogenase which showed decreased activities, while the second block, containing the remaining enzymes, displayed increased activity (except for fumarase, which was unchanged). CR also resulted in decreased levels of citrate, glutamate and alpha-ketoglutarate, increased levels of malate, and unchanged levels of aspartate. The alpha-ketoglutarate/glutamate and malate/alpha-ketoglutarate ratios were higher in CR, in parallel with previously reported increases with CR in pyruvate carboxylase activity and glucagon levels, respectively. The results indicate that long-term CR induces a differential regulation of Krebs cycle in old mice and this regulation may be the result of changes in gene expression levels, as well as a complex interplay between enzymes, hormones and other effectors. Truncation of Krebs cycle by CR may be an important adaptation to utilize available substrates for the gluconeogenesis necessary to sustain glycolytic tissues, such as brain.
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Affiliation(s)
- Kevork Hagopian
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, One Shields Avenue, Davis, CA 95616, USA.
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Brosnan JT, Brosnan ME, Nissim I. A window into cellular metabolism: hepatic metabolism of 15N-labelled substrates. Metab Eng 2004; 6:6-11. [PMID: 14734251 DOI: 10.1016/j.ymben.2003.10.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
It is now apparent that many of the subtleties of cellular metabolism are intrinsically associated with cell structure and that their physiological study requires techniques that respect the integrity of cells and organs. We have used 15N-substrates to examine urea synthesis in the intact perfused rat liver. This work permits us to determine the extent to which different amino acids donate nitrogen atoms to the two nitrogens of urea. It is apparent that alanine and the amino group of glutamine provide nitrogen for urea synthesis primarily via cytoplasmic aspartate, whereas mitochondrial ammonia is the preferred route of entry for nitrogen from pre-formed ammonia or from the amide nitrogen of glutamine. Most importantly, this methodology permits us to explore for the occurrence of metabolic channels in such a highly organised, physiological system. Our studies indicate that a metabolic channel does not exist between glutaminase and carbamoylphosphate synthetase 1.
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Affiliation(s)
- John T Brosnan
- Department of Biochemistry, Memorial University of Newfoundland, St John's, NF, Canada A1B 3X9.
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Fulco M, Schiltz RL, Iezzi S, King MT, Zhao P, Kashiwaya Y, Hoffman E, Veech RL, Sartorelli V. Sir2 regulates skeletal muscle differentiation as a potential sensor of the redox state. Mol Cell 2003; 12:51-62. [PMID: 12887892 DOI: 10.1016/s1097-2765(03)00226-0] [Citation(s) in RCA: 467] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Sir2 is a NAD(+)-dependent histone deacetylase that controls gene silencing, cell cycle, DNA damage repair, and life span. Prompted by the observation that the [NAD(+)]/[NADH] ratio is subjected to dynamic fluctuations in skeletal muscle, we have tested whether Sir2 regulates muscle gene expression and differentiation. Sir2 forms a complex with the acetyltransferase PCAF and MyoD and, when overexpressed, retards muscle differentiation. Conversely, cells with decreased Sir2 differentiate prematurely. To inhibit myogenesis, Sir2 requires its NAD(+)-dependent deacetylase activity. The [NAD(+)]/[NADH] ratio decreases as muscle cells differentiate, while an increased [NAD(+)]/[NADH] ratio inhibits muscle gene expression. Cells with reduced Sir2 levels are less sensitive to the inhibition imposed by an elevated [NAD(+)]/[NADH] ratio. These results indicate that Sir2 regulates muscle gene expression and differentiation by possibly functioning as a redox sensor. In response to exercise, food intake, and starvation, Sir2 may sense modifications of the redox state and promptly modulate gene expression.
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Affiliation(s)
- Marcella Fulco
- Muscle Gene Expression Group, Laboratory of Muscle Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Schafer FQ, Buettner GR. Redox environment of the cell as viewed through the redox state of the glutathione disulfide/glutathione couple. Free Radic Biol Med 2001; 30:1191-212. [PMID: 11368918 DOI: 10.1016/s0891-5849(01)00480-4] [Citation(s) in RCA: 3156] [Impact Index Per Article: 137.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Redox state is a term used widely in the research field of free radicals and oxidative stress. Unfortunately, it is used as a general term referring to relative changes that are not well defined or quantitated. In this review we provide a definition for the redox environment of biological fluids, cell organelles, cells, or tissue. We illustrate how the reduction potential of various redox couples can be estimated with the Nernst equation and show how pH and the concentrations of the species comprising different redox couples influence the reduction potential. We discuss how the redox state of the glutathione disulfide-glutathione couple (GSSG/2GSH) can serve as an important indicator of redox environment. There are many redox couples in a cell that work together to maintain the redox environment; the GSSG/2GSH couple is the most abundant redox couple in a cell. Changes of the half-cell reduction potential (E(hc)) of the GSSG/2GSH couple appear to correlate with the biological status of the cell: proliferation E(hc) approximately -240 mV; differentiation E(hc) approximately -200 mV; or apoptosis E(hc) approximately -170 mV. These estimates can be used to more fully understand the redox biochemistry that results from oxidative stress. These are the first steps toward a new quantitative biology, which hopefully will provide a rationale and understanding of the cellular mechanisms associated with cell growth and development, signaling, and reductive or oxidative stress.
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Affiliation(s)
- F Q Schafer
- Free Radical Research Institute & ESR Facility, The University of Iowa, Iowa City, IA 52242-1101, USA.
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Abstract
BACKGROUND/AIMS This study aimed to characterize the exchange of fuel substrates in the splanchnic circulation in acute liver failure. METHODS Liver vein catheterization was used in 22 patients with acute liver failure after development of hepatic encephalopathy grade III-IV Healthy controls, patients with cirrhosis and patients with acute on chronic liver disease were also studied. RESULTS In acute liver failure there was splanchnic removal of glucose (0.21+/-0.44 mmol/min), release of lactate (0.34+/-0.37 mmol/min), pyruvate (0.08+/-0.06 mmol/min) and ketone bodies (0.04+/-0.02 mmol/min), while extraction of amino acids and free fatty acids was insignificant. In the acute liver failure group, a normal hepatic venous oxygen saturation (0.69+/-0.12) and normal pyruvate/lactate ratio suggested absence of hypoxia even though the acetoacetate/beta-hydroxybutyrate ratio was decreased. Only in the acute liver failure group did the measured splanchnic oxygen content difference exceed what could be accounted for even by hypothesizing complete oxidation of all extracted blood-borne fuel substrates; oxidation of endogenous substrates may be quantitatively important in this condition. CONCLUSION Acute liver failure was associated with a state of accelerated glycolysis in the splanchnic region, leading to release of lactate in the absence of splanchnic hypoxia.
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Affiliation(s)
- J O Clemmesen
- Department of Hepatology, Rigshospitalet, University of Copenhagen, Denmark.
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Takahashi T, Yamaguchi T, Shitashige M, Okamoto T, Kishi T. Reduction of ubiquinone in membrane lipids by rat liver cytosol and its involvement in the cellular defence system against lipid peroxidation. Biochem J 1995; 309 ( Pt 3):883-90. [PMID: 7639706 PMCID: PMC1135714 DOI: 10.1042/bj3090883] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Rat liver homogenates reduced ubiquinone (UQ)-10 to ubiquinol (UQH2)-10 in the presence of NADPH rather than NADH. This NADPH-dependent UQ reductase (NADPH-UQ reductase) activity that was not inhibited by antimycin A and rotenone, was located mainly in the cytosol fraction and its activity accounted for 68% of that of the homogenates. Furthermore, the NADPH-UQ reductase from rat liver cytosol efficiently reduced both UQ-10 incorporated into egg yolk lecithin liposomes, and native UQ-9 residing in rat microsomes, to the respective UQH2 form in the presence of NADPH. The gross redox ratios of UQH2-9/(UQ-9 + UQH2-9) in individual tissues of rat correlated positively with the log of their respective cytosolic NADPH-UQ reductase activities, while the redox ratios in every intracellular fraction from liver were at about the same level, irrespective of NADPH-UQ reductase activities in the respective fractions. The combined addition of rat liver cytosol and NADPH inhibited to a great extent 2,2'-azobis(2,4-dimethyl-valeronitrile)-induced lipid peroxidation of UQ-10-fortified lecithin liposomes and completely inhibited such peroxidation in the liposomes in which UQH2-10 replaced UQ-10. The NADPH-UQ reductase activity was clearly separated from DT-diaphorase (EC 1.6.99.2) activity by means of Cibacron Blue-immobilized Bio-Gel A-5m chromatography. In conclusion, the NADPH-UQ reductase in cytosol, which is a novel enzyme to our knowledge, was presumed to be responsible for maintaining the steady-state redox levels of intracellular UQ and thereby to act as an endogenous antioxidant in protecting intracellular membranes from lipid peroxidation that is inevitably induced in aerobic metabolism.
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Affiliation(s)
- T Takahashi
- Faculty of Pharmaceutical Sciences, Kobe Gakuin University, Japan
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59
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Qu W, Kauffman FC, Thurman RG. Food restriction and stimulation of monooxygenation of p-nitroanisole in perfused rat liver. Biochem Pharmacol 1994; 48:311-7. [PMID: 8053926 DOI: 10.1016/0006-2952(94)90102-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This study assessed the effect of food restriction on the metabolism of model monooxygenase substrates in the perfused rat liver. Female Sprague-Dawley rats has access ad lib. to a Purina 5001 nonpurified diet (control) or were given 65% of the intake of controls for 3 weeks. Livers were perfused with oxygenated Krebs-Henseleit buffer using a non-recirculating system, and the rates of monooxygenation of p-nitroanisole and 7-ethoxycoumarin were measured. The results indicate that food restriction stimulated p-nitroanisole O-demethylation from 2.9 +/- 0.2 to 4.6 +/- 0.5 mumol/(g.hr) when saturating concentrations of p-nitroanisole were infused. Concomitantly, the ratio of beta-hydroxybutyrate to acetoacetate (B/A) and the rates of ketogenesis (B + A) were increased significantly by food restriction. Further, p-nitroanisole (200 mumol/L) increased hepatic malate concentration nearly 3-fold in liver extracts from food-restricted rats. However, infusion of either a low concentration of p-nitroanisole (50 mumol/L) or 7-ethoxycoumarin (200 mumol/L) did not alter these parameters. On the other hand, food restriction did not alter rates of monooxygenation in isolated microsomes supplemented with excess NADPH. Taken together, these data support the hypothesis that high concentrations of p-nitroanisole increased monooxygenation in food-restricted rats by stimulating fatty acid oxidation, which elevates the mitochondrial NADH/NAD+ ratio. This, in turn, increases the availability of reducing equivalents in the form of NADPH by a malate-pyruvate exchange system, leading to increased drug metabolism.
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Affiliation(s)
- W Qu
- Department of Pharmacology, University of North Carolina at Chapel Hill, 27599-7365
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Rossini L, Bernardi M, Concettoni C, De Florio L, Deslauriers R, Moretti V, Piantelli F, Pigini P, Re L, Rossini P. Some approaches to the pharmacology of multisubstrate enzyme systems. Pharmacol Res 1994; 29:313-35. [PMID: 7971684 DOI: 10.1016/1043-6618(94)80054-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Analytical and exploratory in vitro, in situ and in vivo, physio-pharmacotoxicology, from enzymology to population epidemiology, now embraces those approaches that correlate complex dynamic multisubstrate kinetics through conventional and more recent non-invasive quantitative methodologies. Basically, substrates may be classed as pertaining to fundamental energy turnovers (first-order cellular metabolic pathways or networks) and to iso- vs allosteric modulator systems (second-order metabolic control network). Pairs of substrates and cofactors set-up the third-order multienzyme-receptor patterns, which in intact, native in vivo structures establish and maintain the compartmentalized, dynamically superimposed overall coordination of local redox and phosphate potentials. Perturbations of the various levels of the metabolic hierarchy induced by drugs, as well their relaxations, can be readily submitted to non-invasive kinetic analysis. Both indirect and direct titrations of substrate levels, their modelling and statistical ad hoc evaluations of their interrelations can lead to the identification of the multiple sites involved in drug effects as structured at the different orders/levels of concomitant functional variations. Fractal geometries contribute towards defining the space- and time-related events.
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Affiliation(s)
- L Rossini
- Institute of Experimental and Clinical Medicine-Pharmacology, University of Ancona, Italy
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Laouari D, Jurkovitz C, Burtin M, Bois B, Vassault A, Kleinknecht C. Uremia-induced disturbances in hepatic carbohydrate metabolism: enhancement by sucrose feeding. Metabolism 1994; 43:403-12. [PMID: 8159094 DOI: 10.1016/0026-0495(94)90067-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A high-sucrose (S) diet accentuates anorexia and stunts growth in uremic (U) rats, and an oral S load induces a greater hyperfructosemia in U rats than in control (C) rats. Four studies were performed to determine the roles of S feeding and an acute S load on liver carbohydrate (CHO) metabolism in U and C rats (eight to 10 rats per group). We also examined the plasma responses to either water or a S load. Levels of the main metabolites of glycolysis, gluconeogenesis, and glycogenesis were measured under basal conditions (7 hours' postmeal) in U and C rats fed either a cornstarch diet (study I) or S diet (study II) and at 30 and 60 minutes after an intragastric S load (studies III and IV) in s-fed U and C rats. The weight gain, food intake, and plasma creatinine and urea levels of the rats in the four studies were comparable. Weight gain and liver weight (g/100 g body weight) were lower in U than in C rats. In the plasma, baseline levels of lactate were decreased by uremia and S feeding and those of glucose (G) were increased by S feeding. The increases in plasma G and fructose (F) levels after a S load were greater in U rats than in C rats, whereas those of plasma lactate were comparable. In the liver under basal conditions, uremia markedly decreased levels of glycogen, F-1,6-diphosphate (F-1,6-diP), F-2,6-diP, 3-glycero-phosphate (3-glycero-P), dihydroxyacetone phosphate (DHAP), pyruvate, lactate, and adenosine triphosphate (ATP), and the phosphorylation state (ATP/adenosine diphosphate [ADP] x inorganic phosphorus [PI]), increased phosphoenolpyruvate (PEP), ADP, and Pi levels, but did not affect the cytosolic redox state (pyruvate/lactate). In addition to uremia, S feeding further decreased levels of glycogen, F-2,6-diP, 3-glycero-P, and ATP. After S loading, liver F levels increased more in U than in C rats, but glycogen and 3-glycero-P levels increased less in U than in C rats. Liver lactate and pyruvate levels increased more in U than in C rats, and the pyruvate/lactate and DHAP/3-glycero-P ratios were higher in U than in C rats after a S load. The ATP level and the phosphorylation state in U rats increased 30 minutes later in U than in C rats. Our findings indicate that uremia causes a depletion in liver glycogen, which is enhanced by S feeding and could be partially attributed to decreased glycogen synthesis.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- D Laouari
- INSERM U.192, Hôpital des Enfants Malades, Paris, France
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Donohoe JA, Rosenfeldt FL, Munsch CM, Williams JF. The effect of orotic acid treatment on the energy and carbohydrate metabolism of the hypertrophying rat heart. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1993; 25:163-82. [PMID: 8444313 DOI: 10.1016/0020-711x(93)90004-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
1. Adenine nucleotide concentrations in normal and one day hypertrophied hearts of untreated, orotic acid (OA), uridine, uracil, dihydroorotate and reserpine pretreated rats were measured. OA treatment increased the ADP concentration 5-fold in one day hypertrophied hearts. Neither uracil, uridine, dihydroorotate nor reserpine treatments changed ADP or total adenylate concentrations at one day of hypertrophy. 2. The adenine nucleotide ratio (ANR) at 0.263 x 10(3) M-1 and the energy charge (0.66) were at their lowest values in OA and in reserpine treated one day hypertrophying hearts. The temporal decline in the indices of energy metabolism corresponded with the OA induced maximum stimulation of contractility and maximum rates of protein, RNA and glycogen synthesis. 3. The phosphorylation state of the adenine nucleotides (PSAN) was both the most sensitive and the best predictive index of the cellular energy status in normal and hypertrophying hearts. The pronounced ability of OA treatment to energize myocyte cytoplasm was shown by the 9- and 6-fold greater values of PSAN over ANR in one and three day hypertrophied hearts. The enhanced PSAN may be the key factor in the mechanism of OA induced enhancement of contractile and synthetic functions of the heart in compensatory hypertrophy. 4. The development of myocardial hypertrophy in untreated rats resulted in a 36% reduction in the cytoplasmic NAD/NADH ratio. In rats treated with OA this redox couple of the hypertrophying heart was more oxidized and was increased by 30% to restore it to the value range of normal heart. 5. The regulatory status of the glycolytic pathway in untreated and OA treated hypertrophying hearts was assessed by comparisons of the mass action ratio (MAR) and equilibrium constants for each of the individual glycolytic reactions. There was an OA induced 2.7-fold increase in glycogen, UDP-glucose and total uridine nucleotides in hypertrophied hearts. The concentrations of seven out of ten glycolytic intermediates, including pyruvate and lactate were increased as a consequence of OA treated hypertrophy. Glycolytic flux was not stalled, rather the pathway was "more open" permitting greater throughput of intermediates with individually increased levels of selected metabolites. OA stimulated hypertrophy did not change the canonical control of glycolysis by the activities and individual MAR values of phosphofructokinase and pyruvic kinase. 6. Elevated levels of Glu 6-P, Fru 6-P and DHAP can force glycolytic intermediate entry into the non-oxidative reaction segment of the pentose pathway (PP), thereby elevating Rib 5-P concentration by reversal of the conventional flux direction of PP.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- J A Donohoe
- Division of Biochemistry and Molecular Biology, Faculty of Science, Australian National University, Canberra ACT
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Kashimoto S, Nakagomi M, Nonaka A, Kumazawa T. The effects of ulinastatin on cardiac and hepatic energy metabolism in rats subjected to hypovolemic shock. J Anesth 1990; 4:40-4. [PMID: 15236015 DOI: 10.1007/s0054000040040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/1988] [Accepted: 06/05/1989] [Indexed: 10/26/2022]
Abstract
Ulinastatin is a trypsin inhibitor extracted from human urine. In this study the effects of ulinastatin on myocardial and hepatic tissue concentrations of creatine phosphate (CP), ATP, ADP, AMP, lactate, pyruvate, and glycogen have been investigated in rats which were in hemorrhagic shock state. Hypovolemia was induced by bleeding from the femoral artery, and systolic blood pressure was maintained 40 mmHg for 25 min, then ulinastatin 50,000 units.kg(-1) in saline or saline vehicle was intravenously administered. Thereafter the heart and liver were extirpated and frozen quickly with liquid nitrogen. The tissue concentrations of CP, ATP, ADP, AMP, lactate and glycogen were measured enzymatically. Systolic blood pressure elevated significantly after ulinastatin administration. The myocardial tissue CP level was higher in ulinastatin-treated group than that of control group, whereas no significant difference in energy charge between two groups. The hepatic tissue level of AMP, lactate and L/P ratio was lower in ulinastatin-treated group than that of control group, however, no significant difference was found in hepatic tissue level of ATP, ADP and energy charge. From these results it is concluded that ulinastatin can improve the energy metabolism of myocardium to some extent, but not of the liver in rats with hypovolemic shock.
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Affiliation(s)
- S Kashimoto
- Department of Anesthesiology, Yamanashi Medical College, Yamanashi-ken, Japan
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Nam YT, Takahashi S, Tominaga M, Yoshitake J. The hemodynamic and metabolic changes in prostaglandin E1-induced hypotension in dogs--a comparative study with trimetaphan-induced hypotension. J Anesth 1989; 3:210-7. [PMID: 15236040 DOI: 10.1007/s0054090030210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/1989] [Accepted: 04/13/1989] [Indexed: 10/26/2022]
Abstract
The hemodynamic and metabolic changes in hypotensive state induced with prostaglandin E1 (PGE1) or trimetaphan (TMT) infusion were investigated in dogs. Mean arterial pressure was decreased by about 50% with 1.58 microg/kg/min of PGE1 or 45 microg/kg/min of TMT. Heart rate, pulmonary capillary wedge pressure and central venous pressure remained virtually unchanged in the two groups. Cardiac output was well maintained in PGE1 group, whereas cardiac output showed the tendency to decline in TMT group. Greater reduction in systemic vascular resistance was seen in PGE1 group than in TMT group. Pulmonary vascular resistance showed no significant change in PGE1 group, whereas it increased significantly in TMT group. Gradual decreases in arterial pH, PaO2 and base excess and slight but significant increase in PaCO2 was observed in PGE1 group, and these abnormalities recovered 30 min after hypotension. Abnormalities in blood gases and acid-base balance were considerably more severe and prolonged in TMT group compared with those in PGE1 group. Blood lactate and pyruvate concentrations showed no significant changes in PGE1 group, whereas substantial elevation was seen in L/P ratio especially 30 min after induction of hypotension in TMT group. Oxygen consumption showed minimal changes in PGE1 group, whereas a significant decrease was observed in TMT group. The conclusions derived from these results are as follows; 1) PGE1 maintained cardiac output better than TMT, probably because of its direct inotropic action on the heart, and of its greater reduction of systemic vascular resistance than TMT. 2) PGE1 seemed to provide the better blood perfusion throughout the body than TMT. 3) PGE1 showed less possibility to produce the metabolic derangement compared with TMT.
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Affiliation(s)
- Y T Nam
- Department of Anesthesiology, Yonsei University College of Medicine, Severance Hospital, Seoul, Korea
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Keleti T, Ovádi J, Batke J. Kinetic and physico-chemical analysis of enzyme complexes and their possible role in the control of metabolism. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1989; 53:105-52. [PMID: 2692072 DOI: 10.1016/0079-6107(89)90016-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Veech RL, Gitomer WL. The medical and metabolic consequences of administration of sodium acetate. ADVANCES IN ENZYME REGULATION 1988; 27:313-43. [PMID: 2854950 DOI: 10.1016/0065-2571(88)90024-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
1. The standard total parenteral nutrition, peritoneal dialysis, hemodialysis and many surgical fluids in use today contain 36 to 45 mM D,L-lactate or 2 to 140 mM acetate whereas the normal blood level of D-lactate is 0.02 mM L-lactate 0.5 to 5 mM and acetate 0.1 nM. The reasons for the continued use in patients of such unphysiological concentrations of these anions appear to be historic. 2. Administration of similar concentrations of these anions to the rat causes widespread metabolic disturbances which mimic many of the untoward complications associated with current parenteral and dialysis therapy. Understanding of the mechanisms attendant upon the metabolism of these anions may serve as a guide for designing improved parenteral fluids for human patients. 3. Elevation of blood D-lactate to 5 mM is associated with cerebral dysfunction in human patients. 4. Acetate stimulates the release of the inflammatory leukokine, interleukin-1 from human monocytes. Use of 35 to 45 mM acetate in peritoneal dialysis fluids led to peritoneal fibrosis. Patients exposed to acetate containing hemodialysis fluids have 12-fold elevation in their plasma interleukin-1 levels. 5. Administration of 20 mM sodium acetate to rats leads to a number of metabolic disturbances similar to those seen in human dialysis patients: (a) Acetate elevates blood glucose in the rat and may contribute to the exacerbation of the carbohydrate intolerance seen in uremic patients. (b) Acetate increases the levels of hepatic malonyl CoA, the rate controlling substrate of fatty acid synthesis and may exacerbate the hypertriglyceridemia characteristic of dialysis patients. (c) Acetate administration in the rat leads to a decrease in the cytosolic phosphorylation potential, reduction of the redox state of the free cytosolic NAD couple and paradoxical oxidation of the mitochondrial NAD couple in a pattern analogous to that produced by uncouplers of oxidative phosphorylation and may account in part for the elevation of temperature reported in patients undergoing hemodialysis with acetate. (d) Acetate administration in the rat leads to an increase in intracellular phosphorylated intermediates, adenine nucleotides, inorganic phosphate, inorganic pyrophosphate, calcium and magnesium. On cessation of acetate metabolism, the inorganic phosphate and calcium accumulated intracellularly leave the intracellular space. In patients undergoing hemodialysis, the blood phosphate returns to predialysis levels, within 6 hr after the completion of treatment, leaving significant numbers of patients with chronic hyperphosphatemia and the multiple complications attendant to that state.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- R L Veech
- Laboratory of Metabolism and Molecular Biology, NIAAA, Rockville, Maryland 20852
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Kauffman FC, Evans RK, Jerkins AA, Reinke LA, Conway JG, Thurman RG. Maintenance of nicotinamide dinucleotide phosphate content and oxidation-reduction state during mixed-function oxidation of p-nitroanisole in isolated perfused livers of various species. Biochem Pharmacol 1987; 36:1083-90. [PMID: 3566803 DOI: 10.1016/0006-2952(87)90418-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The influence of p-nitroanisole, a substrate for mixed-function oxidation, on total NADP+ and NADPH and NADP+/NADPH ratios was examined in perfused livers from three different species. Studies were performed using livers from Sprague-Dawley rats, Syrian golden hamsters and C57BL/6J mice. Although rates of p-nitroanisole O-demethylation varied more than 16-fold in perfused livers from these species, NADP+/NADPH ratios calculated from measured concentrations of NADP+ and NADPH and from ratios calculated from substrate pairs assumed to be in near equilibrium with NADP+-dependent dehydrogenases remained remarkably constant under most conditions. Thus, rates of NADPH utilization and generation must be tightly coupled in perfused livers during high rates of mixed-function oxidation. Exceptions to the general pattern noted above occurred in livers of fasted, phenobarbital-treated rats where carbohydrate reserves were depleted and in livers from 3-methyl-cholanthrene-treated mice where rates of p-nitroanisole O-demethylation were exceptionally high. Livers from fed phenobarbital-treated rats displayed a paradoxical decrease in NADP+/NADPH ratios reflecting reduction calculated from substrates assumed to be in near equilibrium with 6-phosphogluconate dehydrogenase during mixed-function oxidation, suggesting that NADPH generation exceeded NADPH utilization in the rat in the fed state. In contrast, the NADP+/NADPH ratio calculated from measured pyridine nucleotides increased in livers of 3-methylcholanthrene-treated mice perfused with p-nitroanisole, reflecting oxidation. Moreover, the NADP+/NADPH ratio calculated from substrates assumed to be near equilibrium with 6-phosphogluconate dehydrogenase increased in livers of fasted rats, suggesting that utilization of NADPH exceeded generation. Thus, adequate carbohydrate reserves appear essential for maintenance of NADPH during high rates of mixed-function oxidation.
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68
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Srivastava DK, Bernhard SA. Enzyme-enzyme interactions and the regulation of metabolic reaction pathways. CURRENT TOPICS IN CELLULAR REGULATION 1986; 28:1-68. [PMID: 3539532 DOI: 10.1016/b978-0-12-152828-7.50003-2] [Citation(s) in RCA: 134] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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69
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Matthews PM, Shen LF, Foxall D, Mansour TE. 31P-NMR studies of metabolite compartmentation in Fasciola hepatica. BIOCHIMICA ET BIOPHYSICA ACTA 1985; 845:178-88. [PMID: 3995088 DOI: 10.1016/0167-4889(85)90175-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Fasciola hepatica, the common liver fluke, is an anaerobic parasitic worm. Possible compartmentation of metabolites between different cell types, metabolic compartments, and free and macromolecule-bound species was investigated using 31P-NMR. A spectrum of the intact worm shows unusual metabolic features, among which are large amounts of glycerolphosphorylcholine, phospholipids mobile on the NMR time-scale, and free cytosolic ADP. Spectra from cells as different as those in oral sucker tissue and eggs showed similar features. Acidosis after serotonin administration was associated with parallel changes in chemical shifts of intracellular Pi and glucose 6-phosphate, suggesting that they are in the same metabolic compartment. Although 13.4 +/- 1.1 mumol/g wet wt. (n = 3) Mg2+ is present in fluke tissue, a considerable fraction is sequestered out of the cytosol. The intracellular free [Mg2+] was independently estimated from the chemical shifts of ATP and ADP as 1.6 +/- 0.5 mM and 2.9 +/- 0.7 mM, respectively. Quantitation of observable phosphate-containing metabolites in whole tissue and in perchlorate extracts demonstrated that 60% of the total ADP and 50% of the total Pi are 'NMR-invisible' in the intact fluke and therefore probably bound to macromolecules in the cells. The apparent ATP/ADP X Pi free concentration ratio is much lower in this anaerobic tissue than in mammalian oxidative tissues.
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70
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Kaminsky YG, Kosenko EA, Kondrashova MN. Analysis of the circadian rhythm in energy metabolism of rat liver. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1984; 16:629-39. [PMID: 6468728 DOI: 10.1016/0020-711x(84)90032-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
To study the temporal organization of energy metabolism in rat liver the steady state concentrations of key intermediates of carbohydrate and phosphorus metabolism were determined during 24 hr. The circadian rhythm in energy metabolism of rat liver has been analysed by four different approaches. It was shown that neither apparent PEP synthesis nor crossover theorem were acceptable for the elucidation of the temporal organization of multi-enzyme systems. Correlations analysis explained the temporal organization of energy metabolism most satisfactorily. Based on the results of this analysis it was suggested that circadian regulation of energy metabolism in liver was realized at the level of the citric acid cycle.
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71
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Cornell NW. Properties of alcohol dehydrogenase and ethanol oxidation in vivo and in hepatocytes. Pharmacol Biochem Behav 1983; 18 Suppl 1:215-21. [PMID: 6356160 DOI: 10.1016/0091-3057(83)90174-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Studies in this laboratory have been concerned with testing the properties of alcohol dehydrogenase (ADH) in vitro as predictors of ethanol oxidation in the rat in vivo. With the kinetic constants for the extracted enzyme determined under physiological conditions (pH 7.3, ionic strength = 0.25, 38 degrees C), it was possible to predict rates of ethanol elimination in the rat in vivo within +/- 15%. The results indicate that the level of ADH is the major rate determining factor and that physiological levels of free cytosolic NADH have a minor influence (less than or equal to 20%) on the rate of ethanol oxidation in vivo. Those conclusions are supported by results with isolated hepatocytes which, when incubated without other substrates, oxidize ethanol at 1/3 the rate in vivo. Under that condition, titrations with 4-pentylpyrazole show that ADH is not rate determining, and acceleration of NADH reoxidation stimulates ethanol removal. When hepatocyte incubations are supplemented with substrates, ethanol oxidation proceeds at rates similar to those in vivo, and the rates are, as in vivo, determined largely by the cellular content of ADH.
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72
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van den Thillart G, van Waarde A, Dobbe F, Kesbeke F. Anaerobic energy metabolism of goldfish,Carassius auratus (L.). J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1982. [DOI: 10.1007/bf00688715] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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73
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Mooney RA, Lane MD. Control of ketogenesis and fatty-acid synthesis at the mitochondrial branch-point for acetyl-CoA in the chick liver cell: effect of adenosine 3',5'-monophosphate. EUROPEAN JOURNAL OF BIOCHEMISTRY 1982; 121:281-7. [PMID: 6277621 DOI: 10.1111/j.1432-1033.1982.tb05783.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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74
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Pardridge WM, Duducgian-Vartavarian L, Casanello-Ertl D, Jones MR, Kopple JD. Effects of clofibric acid on amino acid metabolism in cultured rat skeletal muscle. THE AMERICAN JOURNAL OF PHYSIOLOGY 1981; 240:E203-8. [PMID: 7468794 DOI: 10.1152/ajpendo.1981.240.2.e203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Well-differentiated cultured skeletal muscle cells (myotubes) obtained from adult rats were incubated for up to 48 h in Dulbecco's modified Eagle's medium. Medium glucose decreased from 4.9 +/- 0.1 mM at 0 h to 13 +/- 1 microM by 24 h; approximately 60% of glucose was converted to lactate. Pyruvate, alanine, and citrate were continuously produced, even during the period of 24-48 h when no glucose or lactate utilization was observed. Branched-chain amino acid utilization increased more than fourfold during the incubation period of 24-48 h; during this time, intracellular ATP, pyruvate, alpha-ketoglutarate, malate, and citrate levels were constant despite the absence of glucose or lactate consumption. Incubation of muscle cells with 2 mM clofibric acid resulted in a 76% inhibition of leucine metabolism. Coincident with the drug-induced inhibition of a branched-chain amino acid utilization, alanine and citrate production was blocked, and cell levels of pyruvate, alpha-ketoglutarate, malate, and citrate were markedly reduced. These studies suggest branched-chain amino acids contribute significantly to anaplerotic pathways in cultured skeletal muscle cells and that these pathways lead to the net production of alanine and citrate during periods of minimal carbohydrate utilization.
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75
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Lane MD, Mooney RA. Tricarboxylic acid cycle intermediates and the control of fatty acid synthesis and ketogenesis. CURRENT TOPICS IN CELLULAR REGULATION 1981; 18:221-42. [PMID: 6168431 DOI: 10.1016/b978-0-12-152818-8.50019-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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76
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Kauffman FC, Evans RK, Reinke LA, Belinsky SA, Ballow C, Thurman RG. Effects of 3-methylcholanthrene on oxidized nicotinamide-adenine dinucleotide phosphatedependent dehydrogenases and selected metabolites in perfused rat liver. Biochem Pharmacol 1980; 29:697-700. [DOI: 10.1016/0006-2952(80)90542-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/1979] [Accepted: 09/20/1979] [Indexed: 11/17/2022]
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77
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Jansen R, Reichl JR. [Effect of varying protein contents of feed on the concentration of metabolites, NAD+/NADH-redox states and enzyme activities in the liver of rats]. ZEITSCHRIFT FUR ERNAHRUNGSWISSENSCHAFT 1980; 19:57-65. [PMID: 7385921 DOI: 10.1007/bf02021074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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78
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Pardridge WM, Duducgian-Vartavarian L, Casanello-Ertl D, Jones MR, Kopple JD. Glucose and amino acid metabolism in neonatal rat skeletal muscle in tissue culture. J Cell Physiol 1980; 102:91-8. [PMID: 7372720 DOI: 10.1002/jcp.1041020113] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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79
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Zahradník FJ. Streptococcal extracellular NAD+ nucleosidase. Characterization of changes occurring during purification. Folia Microbiol (Praha) 1980; 25:40-9. [PMID: 6243600 DOI: 10.1007/bf02876396] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Purification of streptococcal extracellular NAD+ nucleosidase is associated with changes of kinetic properties. A high-molecular weight component is required for a full activity of the enzyme. The component is not produced by bacteria and is present in the Todd-Hewitt cultivation medium, the beef-heart extract serving primarily as its source. In its effect on the enzyme this component can be replaced with bovine albumin. It follows from the time relationship of the NAD decomposition that the mechanism of the studied enzymic reaction is not hydrolytic. In addition to nicotinamide, a product of polymeric character is formed.
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80
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Feraudi M. Determination of metabolite compartition in hepatic cells by varying the redox state in vivo. ARCHIVES INTERNATIONALES DE PHYSIOLOGIE ET DE BIOCHIMIE 1979; 87:915-23. [PMID: 94822 DOI: 10.3109/13813457909070539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In the present study, metabolite (lactate, pyruvate, glycerol 3-phosphate, dihydroxyacetone phosphate) concentrations were measured in various redox states. The mathematical relations between metabolite concentrations in various redox states were expressed algebraically and studied. Models which provided separate lactate/pyruvate (L/P) and glycerol 3-phosphate/dihydroxyacetone phosphate (G/D) spaces correspond to the experimental results in the case of "reductants" (e.g. ethanol, acetaldehyde, dihydroxyacetone and acetate) or of "oxidizing agents" (e.g. pyruvate) of the cytosolic NAD-NADH. Crotonate injection caused an oxidation of cytosolic redox couples, but no separation of the lactate/pyruvate space from the glycerol 3-phosphate/dihydroxyacetone phosphate space may necessarily be inferred. Furthermore, the following statements could be made in both first cases: (i.e. of "reductants" and "oxidizing agents"): (a) Redox couples in L/P space and in G/D space (together L/P-G/D system) are in equilibrium; (b) Redox-equivalent transport from the L/P space to the G/D space is not subject to any velocity-limiting mechanism; (c) Substrates which transports redox-equivalents into and from the L/P-G/D system reach concentrations to values, which are in a linear relation to each other in this system; (d) It is possible that these substrates are regenerated in another system which is also in equilibrium and subject to statement c.
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Bautista J, Satrústegui J, Machado A. Evidence suggesting that the NADPH/NADP ratio modulates the splitting of the isocitrate flux between the glyoxylic and tricarboxylic acid cycles, in Escherichia coli. FEBS Lett 1979; 105:333-6. [PMID: 39785 DOI: 10.1016/0014-5793(79)80642-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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83
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Reinke LA, Thurman RG, Kauffman FC. Oxidation-reduction state of free NADP+ during mixed-function oxidation in perfused rat livers--Evaluation of the assumptions of near equilibrium by comparisons of surface fluorescence changes and calculated NADP+:NADPH ratios. Biochem Pharmacol 1979; 28:2381-7. [PMID: 40558 DOI: 10.1016/0006-2952(79)90704-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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84
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Fiskum G, Lehninger AL. Regulated release of Ca2+ from respiring mitochondria by Ca2+/2H+ antiport. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(18)50352-5] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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85
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La Noue KF, Duszynski J, Watts JA, McKee E. Kinetic properties of aspartate transport in rat heart mitochondrial inner membranes. Arch Biochem Biophys 1979; 195:578-90. [PMID: 38752 DOI: 10.1016/0003-9861(79)90384-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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86
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Pardridge WM, Davidson MB. Alanine metabolism in skeletal muscle in tissue culture. BIOCHIMICA ET BIOPHYSICA ACTA 1979; 585:34-42. [PMID: 444590 DOI: 10.1016/0304-4165(79)90322-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Alanine production by skeletal muscle in tissue culture was studied using an established myogenic line (L6) of rat skeletal muscle cells. Correlation analyses were performed on rates of metabolism of alanine, glucose, lactate and pyruvate over incubation periods up to 96 h. Alanine production did not correlate significantly with glucose utilization (r = 0.24, P less than 0.20). Alanine production, however, did correlate with lactate production (r = 0.72, P less than 0.0005) as well as medium (r = 0.50, P less than 0.025) and intracellular (r = 0.85, P less than 0.0005) pyruvate concentrations. The intercepts of the latter two correlation analyses indicated that when medium or cell pyruvate fell below 0.28 mM or 1 nmol/mg protein, respectively, net alanine consumption occurred. Alanine synthesis also correlated (r = 0.71, P less than 0.0005) with the percent change in the cell mass action ratio for the sum of the alanine and aspartate aminotransferase reactions, i.e., [alanine] [malate]/[aspartate] [lactate]. These results suggest that alanine production is not necessarily linked to the rate of glucose utilization but rater to pyruvate overflow above a critical intracellular level; under conditions of pyruvate overflow, alanine synthesis is driven by the tendency to establish equilibrium between metabolites of the linked amino acid transaminases in skeletal muscle.
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87
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Pardridge WM, Casanello-Ertl D. Effects of glutamine deprivation on glucose and amino acid metabolism in tissue culture. THE AMERICAN JOURNAL OF PHYSIOLOGY 1979; 236:E234-8. [PMID: 426054 DOI: 10.1152/ajpendo.1979.236.3.e234] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The effects of glutamine deprivation on cultured skeletal muscle cells were analyzed by incubating 10-day-old myotube preparations in glutamine free Dulbecco's modified Eagle medium containing 10% fetal calf serum for up to 48 h. Under these conditions net glutamine production was not observed, but active ammonia production (average rate = 1.0 nmol/min . mg protein) continued despite glutamine withdrawal. Glutamine deprivation was associated with a progressive depletion of intracellular aspartate and glutamate. Maximal aspartate depletion correlated with a 15-fold increase in the intracellular lactate:pyruvate ratio and a 3-fold decrease in the estimated intracellular glutamate:(alpha-ketoglutarate) (ammonia) ratio. Despite wide shifts in cell metabolite concentrations, the mass action ratios of alanine and aspartate aminotransferase approximated the expected equilibria constants. These results suggest that 1) glutamine deprivation is associated with a marked reduction of aspartate, and the maintenance of aspartate depletion is due in part to the tendency of aspartate aminotransferase to maintain the metabolites of this reaction at a near equilibrium level; 2) the transport of reducing equivalents from the cytosolic to the mitochondrial compartments via the malate-aspartate shuttle may be limited under conditions of aspartate depletion.
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88
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Pardridge WM, Davidson MB, Casanello-Ertl D. Glucose and amino acid metabolism in an established line of skeletal muscle cells. J Cell Physiol 1978; 96:309-18. [PMID: 670313 DOI: 10.1002/jcp.1040960306] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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89
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Schoolwerth A, Nazar B, LaNoue K. Glutamate dehydrogenase activation and ammonia formation by rat kidney mitochondria. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(17)34596-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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90
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Feraudi M. Rat-liver cell compartition as revealed by correlations between redox-quotient changes following alloxan treatment, starvation, carbohydrate- and fat-diet. ARCHIVES INTERNATIONALES DE PHYSIOLOGIE ET DE BIOCHIMIE 1978; 86:487-507. [PMID: 83818 DOI: 10.3109/13813457809055919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
As reported elsewhere (FERAUDI, 1976a & b), we have studied the mathematical relations between metabolite concentrations in the rat liver at various redox states and expressed them algebraically. In the present work we have measured the liver-cell concentrations of lactate, pyruvate, glycerol 3-phosphate, dihydroxyacetone phosphate, malate, oxaloacetate, beta-hydroxybutyrate, acetoacetate, 2-oxoglutarate, ribulose 5-phosphate as pentose phosphates, gluconate 6-phosphate, isocitrate, aspartate in untreated and treated rats (alloxan-diabetic, insulin-treated alloxan-diabetic or starved rats as well as rats fed on carbohydrate- or fat diet). Through analysis of the algebraic correlation between metabolite concentrations, we arrived at the following statements: 1. Under certain physiological conditions the concentration of some metabolites in one compartment determines their total quantity in the cell; 2. NADP and NADPH are comparted within the cytosol; 3. Reduced cosubstrate/oxidized cosubstrate ratios of some enzymic reactions are under certain physiological conditions in mutual equilibrium; 4. Such relationships are first verified after treatment and therefore characterize the metabolite status.
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91
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Heinrich R, Rapoport S, Rapoport T. Metabolic regulation and mathematical models. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1978. [DOI: 10.1016/0079-6107(78)90017-2] [Citation(s) in RCA: 374] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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92
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Panek E, Cook GA, Cornell NW. Inhibition by 5-(tetradecyloxy)-2-furoic acid of fatty acid and cholesterol synthesis in isolated rat hepatocytes. Lipids 1977; 12:814-8. [PMID: 916823 DOI: 10.1007/bf02533270] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Fatty acid and cholesterol synthesis in isolated rat hepatocytes were strongly inhibited by 5-(tetradecyloxy)-2-furoic acid. With either 3H2O or [2(-14)C] acetate as the labeled precursor, the concentrations of inhibitor causing 50% decrease in fatty acid and cholesterol synthesis were, respectively, less than 0.005 mM and 0.020 mM. At 0.1 mM inhibitor, citrate concentration in cells from fed rats was increased by 75%; lactate and pyruvate concentrations were decreased by 30%; ethanol oxidation was decreased by 20%; with cells from starved rats, the mitochondrial [NAD+]/[NADH] was decreased. Other parameters were unaffected. Both its potency and its specificity indicate that 5-(tetradecyloxy)-2-furoic acid will be useful in studies on the regulation of lipid biosynthesis.
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93
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Parrilla R, Goodman MN, Toews CJ. The effect of anoxia on nitrogen metabolism in the isolated perfused rat liver. Pflugers Arch 1977; 369:167-75. [PMID: 560678 DOI: 10.1007/bf00591573] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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94
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Milkowski AL, Lardy HA. Factors affecting the redox state of bovine epididymal spermatozoa. Arch Biochem Biophys 1977; 181:270-7. [PMID: 195533 DOI: 10.1016/0003-9861(77)90505-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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95
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Thauer RK, Jungermann K, Decker K. Energy conservation in chemotrophic anaerobic bacteria. BACTERIOLOGICAL REVIEWS 1977; 41:100-80. [PMID: 860983 PMCID: PMC413997 DOI: 10.1128/br.41.1.100-180.1977] [Citation(s) in RCA: 1326] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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96
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97
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98
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Cassan SM, Simmons DH. Nitrogen dioxide and the erythrocyte redox state. ARCHIVES OF ENVIRONMENTAL HEALTH 1975; 30:502-6. [PMID: 170872 DOI: 10.1080/00039896.1975.10666763] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Normal human erythrocytes were exposed for two hours at 38 C to an atmosphere of air containing variable concentrations of nitrogen dioxide, in order to detect any primary cytoplasmic effect of NO2 on the calculated oxidation-reduction (redox) ratio ([NAD+]/[NADH]) of a mitochondria-free cell. Substantial increases in the redox ratio were noted only when NO2 concentrations exceeded 15 ppm. In the range of 15 to 500 ppm NO2, the increase in the redox ratio significantly correlated with the NO2 concentration (r=.71; p less than .01). Intracellular to extracellular anion distribution ratios for chloride, lactate, and pyruvate were similar in NO2 and non-NO2 exposed cells, suggesting absence of a substantial hemolytic effect. These data identify a direct cytoplasmic NO2-induced biochemical change that may be mediated by a mechanism other than lipid peroxidation. Alteration of hemoglobin or NAD-NADH-dependent enzyme activity is suggested.
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Plasma lactic acid and pyruvic acid concentrations following intragastric infusion of ethanol in adult miniature swine (Sus scrofa). ACTA ACUST UNITED AC 1975. [DOI: 10.1016/0020-711x(75)90067-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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