Effects of increased mechanical work by isolated perfused rat heart during production or uptake of ketone bodies. Assessment of mitochondrial oxidized to reduced free nicotinamide-adenine dinucleotide ratios and oxaloacetate concentrations

Opie, Lionel H.; Owen, Philip

doi:10.1042/bj1480403

Cited by 54 publications

(22 citation statements)

References 43 publications

(33 reference statements)

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“…The levels of Nampt have been shown to be upregulated during mild stress of cardiomyocytes, thus supporting the possibility of involvement of the NAD salvage pathway in the regulation of SIRT1 levels during mild stress situations (34). This type of regulation is likely to participate in the induction of SIRT3 levels during physiologic and mild hypertrophy, in which NAD/NADH levels are likely to be elevated (35), but not during severe pathologic hypertrophy and heart failure, in which NAD levels decline due to increased consumption of NAD by overactivation of poly(ADPribose) polymerase-1 (36). There are other mechanisms that can also regulate SIRT1 levels at the level of gene transcription as well as at the posttranscription level by stabilization of mRNA (37).…”

Section: Discussionmentioning

confidence: 92%

Sirt3 blocks the cardiac hypertrophic response by augmenting Foxo3a-dependent antioxidant defense mechanisms in mice

Sundaresan¹,

Gupta²,

Kim³

et al. 2009

J. Clin. Invest.

671

897

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Sirtuin 3 (SIRT3) is a member of the sirtuin family of proteins that promote longevity in many organisms. Increased expression of SIRT3 has been linked to an extended life span in humans. Here, we have shown that Sirt3 protects the mouse heart by blocking the cardiac hypertrophic response. Although Sirt3-deficient mice appeared to have normal activity, they showed signs of cardiac hypertrophy and interstitial fibrosis at 8 weeks of age. Application of hypertrophic stimuli to these mice produced a severe cardiac hypertrophic response, whereas Sirt3-expressing Tg mice were protected from similar stimuli. In primary cultures of cardiomyocytes, Sirt3 blocked cardiac hypertrophy by activating the forkhead box O3a-dependent (Foxo3a-dependent), antioxidant-encoding genes manganese superoxide dismutase (MnSOD) and catalase (Cat), thereby decreasing cellular levels of ROS. Reduced ROS levels suppressed Ras activation and downstream signaling through the MAPK/ERK and PI3K/Akt pathways. This resulted in repressed activity of transcription factors, specifically GATA4 and NFAT, and translation factors, specifically eukaryotic initiation factor 4E (elf4E) and S6 ribosomal protein (S6P), which are involved in the development of cardiac hypertrophy. These results demonstrate that SIRT3 is an endogenous negative regulator of cardiac hypertrophy, which protects hearts by suppressing cellular levels of ROS.

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Section: Discussionmentioning

confidence: 92%

Sirt3 blocks the cardiac hypertrophic response by augmenting Foxo3a-dependent antioxidant defense mechanisms in mice

Sundaresan¹,

Gupta²,

Kim³

et al. 2009

J. Clin. Invest.

671

897

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“…This estimate assumes 48 mg of mitochondrial protein/g wet wt. of heart (Farmer et al, 1974), a fresh-weight/ dry-weight ratio of 5 (Opie & Owen, 1975) and that proteins solubilized by ultrasonic treatment account for 22% of total mitochondrial protein (Lin & Davis, 1974). Thus the rate of reduction of pent-4-enoylCoA by the heart mitochondrial extract is about 50-fold less than a minimum estimate of the rate of pent-4-enoate metabolism by the perfused heart.…”

Section: Resultsmentioning

confidence: 99%

Metabolism of pent-4-enoate in rat heart. Reduction of the double bond

Hiltunen¹,

Davis²

1981

Biochemical Journal

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1. Soluble extracts from rat heart and liver mitochondria were used to evaluate the early steps in the conversion of pent-4-enoyl-CoA into tricarboxylic acid-cycle intermediates. Hitherto the unresolved problem was the reduction of the double bond of pent-4-enoate. 2. Soluble extracts from heart mitochondria reduced pent-4-enoyl-CoA and penta-2,4-dienoyl-CoA in the presence of NADPH at rates (nmol/min per mg of protein) of 0.9 + 0.1 and 132 + 8 and from the liver mitochondria at the rates of 1.9 + 0.2 and 52 + 6 respectively. No reduction of acryloyl-CoA was found. 3. We show that primarily the double bond in position 4, not in position 2, of penta-2,4-dienoyl-CoA is reduced. 4. It is concluded that the principal metabolic pathway of penta-4-enoate is reduction of the double bond in position 4 after an initial oxidation to penta-2,4-dienoyl-CoA. The pent-2-enoyl-CoA thus formed can be further metabolized by the usual enzymes of f-oxidation, and by the further metabolism of propionyl-CoA to tricarboxylic acid-cycle intermediates.The hypoglycaemic agent pent-4-enoate inhibits fatty acid oxidation under many different kinds of conditions (e.g. Senior et al., 1968;Brendel et al., 1969;Fukami & Williamson, 1971). Pent-4-enoate itself can be slowly metabolized through #-oxidation, forming acetyl-CoA and acryloyl-CoA as end products (Brendel et al., 1969;, and the inhibition is apparently caused by some inhibitory intermediates during pent-4-enoate metabolism. We have shown, however, that in perfused rat hearts (Hiltunen, 1978) and in isolated heart mitochondria (Hiltunen et al., 1980) pent-4-enoate causes a rapid increase of tricarboxylic acid-cycle intermediates, and that pent-4-enoate itself is the source of these extra carbon skeletons. The mechanism seems to be that the C3 end products formed during the fl-oxidation of pent-4-enoate are metabolized via the propionate pathway into the tricarboxylic acid cycle.Reduction of the double bond is a prerequisite for the metabolism of pent-4-enoate by a mechanism suggested above. How and at which step of pent-4-enoate metabolism this takes place has remained unclear. We now show in experiments done with soluble extracts from heart and liver mitochondria and intermediates of pent-4-enoate metabolism that only the reduction of penta-2,4-dienoyl-CoA to pent-2-enoyl-CoA is rapid enough to account for the rate of pent-4-enoate metabolism found in perfused heart and liver.

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“…In cardiac tissue, NADH is produced by fatty acid oxidation from acetyl-CoA entering the Krebs cycle and this reaction depends on the BHB/AcAc ratio. 27 As increasing the BHB/ AcAc ratio from 2∶1 to 20∶1 favors the NADH production, we administered BHB (3 mmol∕L) in a basic extracellular solution in the presence of different AcAc concentrations: 1.5 and 150 μmol∕L (2∶1 and 20∶1 ratio, respectively) to vary NADH production. In accordance with decreased NADH concentration in cardiomyocyte mitochondria, the lowered ratio translated into a decrease of the integral fluorescence intensity in components 1 and 2 [ Fig.…”

Section: Sensitivity Of Mitochondrial Nadh Production To Ouabainmentioning

confidence: 99%

Effect of ouabain on metabolic oxidative state in living cardiomyocytes evaluated by time-resolved spectroscopy of endogenous NAD(P)H fluorescence

et al. 2012

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Abstract. Time-resolved spectrometry of endogenous nicotinamide dinucleotide phosphate [NAD(P)H] fluorescence is a useful method to evaluate metabolic oxidative state in living cells. Ouabain is a well-known pharmaceutical drug used in the treatment of cardiovascular disease, the effects of which on myocardial metabolism were recently demonstrated. Mechanisms implicated in these actions are still poorly understood. We investigate the effect of ouabain on the metabolic oxidative state of living cardiac cells identified by time-resolved fluorescence spectroscopy of mitochondrial NAD(P)H. Spectral unmixing is used to resolve individual NAD(P)H fluorescence components. Ouabain decreased the integral intensity of NAD(P)H fluorescence, leading to a reduced component amplitudes ratio corresponding to a change in metabolic state. We also noted that lactate/pyruvate, affecting the cytosolic NADH gradient, increased the effect of ouabain on the component amplitudes ratio. Cell oxidation levels, evaluated as the percentage of oxidized NAD(P)H, decreased exponentially with rising concentrations of the cardiac glycoside. Ouabain also stimulated the mitochondrial NADH production. Our study sheds a new light on the role that ouabain plays in the regulation of metabolic state, and presents perspective on a noninvasive, pharmaceutical approach for testing the effect of drugs on the mitochondrial metabolism by means of time-resolved fluorescence spectroscopy in living cells.

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Effects of increased mechanical work by isolated perfused rat heart during production or uptake of ketone bodies. Assessment of mitochondrial oxidized to reduced free nicotinamide-adenine dinucleotide ratios and oxaloacetate concentrations

Cited by 54 publications

References 43 publications

Sirt3 blocks the cardiac hypertrophic response by augmenting Foxo3a-dependent antioxidant defense mechanisms in mice

Sirt3 blocks the cardiac hypertrophic response by augmenting Foxo3a-dependent antioxidant defense mechanisms in mice

Metabolism of pent-4-enoate in rat heart. Reduction of the double bond

Effect of ouabain on metabolic oxidative state in living cardiomyocytes evaluated by time-resolved spectroscopy of endogenous NAD(P)H fluorescence

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