1
|
Lai N, Fealy CE, Kummitha CM, Cabras S, Kirwan JP, Hoppel CL. Mitochondrial Utilization of Competing Fuels Is Altered in Insulin Resistant Skeletal Muscle of Non-obese Rats (Goto-Kakizaki). Front Physiol 2020; 11:677. [PMID: 32612543 PMCID: PMC7308651 DOI: 10.3389/fphys.2020.00677] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 05/26/2020] [Indexed: 12/25/2022] Open
Abstract
Aim Insulin-resistant skeletal muscle is characterized by metabolic inflexibility with associated alterations in substrate selection, mediated by peroxisome-proliferator activated receptor δ (PPARδ). Although it is established that PPARδ contributes to the alteration of energy metabolism, it is not clear whether it plays a role in mitochondrial fuel competition. While nutrient overload may impair metabolic flexibility by fuel congestion within mitochondria, in absence of obesity defects at a mitochondrial level have not yet been excluded. We sought to determine whether reduced PPARδ content in insulin-resistant rat skeletal muscle of a non-obese rat model of T2DM (Goto-Kakizaki, GK) ameliorate the inhibitory effect of fatty acid (i.e., palmitoylcarnitine) on mitochondrial carbohydrate oxidization (i.e., pyruvate) in muscle fibers. Methods Bioenergetic function was characterized in oxidative soleus (S) and glycolytic white gastrocnemius (WG) muscles with measurement of respiration rates in permeabilized fibers in the presence of complex I, II, IV, and fatty acid substrates. Mitochondrial content was measured by citrate synthase (CS) and succinate dehydrogenase activity (SDH). Western blot was used to determine protein expression of PPARδ, PDK isoform 2 and 4. Results CS and SDH activity, key markers of mitochondrial content, were reduced by ∼10-30% in diabetic vs. control, and the effect was evident in both oxidative and glycolytic muscles. PPARδ (p < 0.01), PDK2 (p < 0.01), and PDK4 (p = 0.06) protein content was reduced in GK animals compared to Wistar rats (N = 6 per group). Ex vivo respiration rates in permeabilized muscle fibers determined in the presence of complex I, II, IV, and fatty acid substrates, suggested unaltered mitochondrial bioenergetic function in T2DM muscle. Respiration in the presence of pyruvate was higher compared to palmitoylcarnitine in both animal groups and fiber types. Moreover, respiration rates in the presence of both palmitoylcarnitine and pyruvate were reduced by 25 ± 6% (S), 37 ± 6% (WG) and 63 ± 6% (S), 57 ± 8% (WG) compared to pyruvate for both controls and GK, respectively. The inhibitory effect of palmitoylcarnitine on respiration was significantly greater in GK than controls (p < 10-3). Conclusion With competing fuels, the presence of fatty acids diminishes mitochondria ability to utilize carbohydrate derived substrates in insulin-resistant muscle despite reduced PPARδ content.
Collapse
Affiliation(s)
- Nicola Lai
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA, United States.,Biomedical Engineering Institute, Old Dominion University, Norfolk, VA, United States.,Department of Mechanical, Chemical and Materials Engineering, University of Cagliari, Cagliari, Italy.,Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States.,Center for Mitochondrial Disease, Case Western Reserve University, Cleveland, OH, United States
| | - Ciarán E Fealy
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Chinna M Kummitha
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
| | - Silvia Cabras
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
| | - John P Kirwan
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States.,Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, United States.,Pennington Biomedical Research Center, Baton Rouge, LA, United States
| | - Charles L Hoppel
- Center for Mitochondrial Disease, Case Western Reserve University, Cleveland, OH, United States.,Department of Pharmacology, Case Western Reserve University, Cleveland, OH, United States.,Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| |
Collapse
|
2
|
Makrecka M, Kuka J, Volska K, Antone U, Sevostjanovs E, Cirule H, Grinberga S, Pugovics O, Dambrova M, Liepinsh E. Long-chain acylcarnitine content determines the pattern of energy metabolism in cardiac mitochondria. Mol Cell Biochem 2014; 395:1-10. [PMID: 24878991 DOI: 10.1007/s11010-014-2106-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 05/15/2014] [Indexed: 01/07/2023]
Abstract
In the heart, a nutritional state (fed or fasted) is characterized by a unique energy metabolism pattern determined by the availability of substrates. Increased availability of acylcarnitines has been associated with decreased glucose utilization; however, the effects of long-chain acylcarnitines on glucose metabolism have not been previously studied. We tested how changes in long-chain acylcarnitine content regulate the metabolism of glucose and long-chain fatty acids in cardiac mitochondria in fed and fasted states. We examined the concentrations of metabolic intermediates in plasma and cardiac tissues under fed and fasted states. The effects of substrate availability and their competition for energy production at the mitochondrial level were studied in isolated rat cardiac mitochondria. The availability of long-chain acylcarnitines in plasma reflected their content in cardiac tissue in the fed and fasted states, and acylcarnitine content in the heart was fivefold higher in fasted state compared to the fed state. In substrate competition experiments, pyruvate and fatty acid metabolites effectively competed for the energy production pathway; however, only the physiological content of acylcarnitine significantly reduced pyruvate and lactate oxidation in mitochondria. The increased availability of long-chain acylcarnitine significantly reduced glucose utilization in isolated rat heart model and in vivo. Our results demonstrate that changes in long-chain acylcarnitine contents could orchestrate the interplay between the metabolism of pyruvate-lactate and long-chain fatty acids, and thus determine the pattern of energy metabolism in cardiac mitochondria.
Collapse
Affiliation(s)
- Marina Makrecka
- Latvian Institute of Organic Synthesis, Aizkraukles Str. 21, Riga, 1006, Latvia,
| | | | | | | | | | | | | | | | | | | |
Collapse
|
3
|
Bhattacharya P, Ross BD, Bünger R. Cardiovascular applications of hyperpolarized contrast media and metabolic tracers. Exp Biol Med (Maywood) 2009; 234:1395-416. [PMID: 19934362 DOI: 10.3181/0904-mr-135] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Modern hyperpolarization technology enhances the recordable magnetic resonance signal four to five orders of magnitude, making in vivo assessments of tracer pathways and metabolic compartments feasible. Existing hyperpolarization instrumentation and previous tracer studies using hydroxyethylpropionate (HEP) as an extracellular marker and 14-carbon label pyruvate as examples are described and reviewed as applicable to the working heart. Future metabolic imaging based on the use of hyperpolarized pyruvate needs to consider extra- and intra-cellular label dilution due to glycolysis, lactate oxidation and protein degradation. This dilution can substantially decrease the recordable signals from PDH flux (oxidative decarboxylation of pyruvate) and other pyruvate pathways. The review of previous literature and data suggests that the (13)C-alanine signal is a better index of mitochondrially oxidized pyruvate than L-lactate. These facts and considerations will help in the interpretation of the in vivo recorded hyperpolarization signals of metabolic tracers and contrast media.
Collapse
Affiliation(s)
- Pratip Bhattacharya
- Enhanced MR Laboratory, Huntington Medical Research Institutes, 10 Pico Street, Pasadena, CA 91105.
| | | | | |
Collapse
|
4
|
Sharma P, Karian J, Sharma S, Liu S, Mongan PD. Pyruvate ameliorates post ischemic injury of rat astrocytes and protects them against PARP mediated cell death. Brain Res 2004; 992:104-13. [PMID: 14604778 DOI: 10.1016/j.brainres.2003.08.043] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This in vitro study was designed to examine the efficacy of exogenous pyruvate and glucose as a fuel substrate to protect rat astrocytes from post-ischemic injury. Astrocytes were incubated in Kreb's buffer deprived of oxygen and glucose for 6 h (ischemia) followed by incubation with added pyruvate or glucose and normoxia for the next 6 h (reperfusion). The transformation of reactive astrocytes in response to various treatments was examined by immunostaining with glial fibrillary acidic protein. The extent of cell damage was evaluated in terms of lactate dehydrogenase leakage from the cells and altered intracellular redox status. The mechanism of cell death was determined by immunoblotting with cytochrome C, caspase-3 and PARP antibodies. The mechanism of the action of pyruvate was determined by measuring the activity of pyruvate dehydrogenase complex, and cellular metabolic status by measuring ATP levels. In comparison to glucose, supply of exogenous pyruvate restored the morphological integrity of post-ischemic astrocytes and prevented gliosis. Pyruvate prevented the cell death of post-ischemic astrocytes by inhibiting the leakage of lactate dehydrogenase, decreasing the redox ratio and restraining the activation of apoptotic events such as release of mitochondrial cytochrome c and fragmentation of caspase-3 and PARP. This study also suggests that pyruvate may accelerate its own metabolism by increasing the activity of pyruvate dehydrogenase and thus restores the cellular ATP levels in post-ischemic astrocytes. Use of pyruvate as an alternate fuel substrate may provide a possibility for the novel therapeutic approach to the treatment of cerebral ischemia.
Collapse
Affiliation(s)
- Pushpa Sharma
- Department of Anesthesiology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | | | | | | | | |
Collapse
|
5
|
MacDonald MJ, Fahien LA, Buss JD, Hasan NM, Fallon MJ, Kendrick MA. Citrate Oscillates in Liver and Pancreatic Beta Cell Mitochondria and in INS-1 Insulinoma Cells. J Biol Chem 2003; 278:51894-900. [PMID: 14522964 DOI: 10.1074/jbc.m309038200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Oscillations in citric acid cycle intermediates have never been previously reported in any type of cell. Here we show that adding pyruvate to isolated mitochondria from liver, pancreatic islets, and INS-1 insulinoma cells or adding glucose to intact INS-1 cells causes sustained oscillations in citrate levels. Other citric acid cycle intermediates measured either did not oscillate or possibly oscillated with a low amplitude. In INS-1 mitochondria citrate oscillations are in phase with NAD(P) oscillations, and in intact INS-1 cells citrate oscillations parallel oscillations in ATP, suggesting that these processes are co-regulated. Oscillations have been extensively studied in the pancreatic beta cell where oscillations in glycolysis, NAD(P)/NAD(P)H and ATP/ADP ratios, plasma membrane electrical activity, calcium levels, and insulin secretion have been well documented. Because the mitochondrion is the major site of ATP synthesis and NADH oxidation and the only site of citrate synthesis, mitochondria need to be synchronized for these factors to oscillate. In suspensions of mitochondria from various organs, most of the citrate is exported from the mitochondria. In addition, citrate inhibits its own synthesis. We propose that this enables citrate itself to act as one of the cellular messengers that synchronizes mitochondria. Furthermore, because citrate is a potent inhibitor of the glycolytic enzyme phosphofructokinase, the pacemaker of glycolytic oscillations, citrate may act as a metabolic link between mitochondria and glycolysis. Citrate oscillations may coordinate oscillations in mitochondrial energy production and anaplerosis with glycolytic oscillations, which in the beta cell are known to parallel oscillations in insulin secretion.
Collapse
Affiliation(s)
- Michael J MacDonald
- Childrens Diabetes Center, University of Wisconsin Medical School, Madison, Wisconsin 53706, USA.
| | | | | | | | | | | |
Collapse
|
6
|
Wojtczak L, Schönfeld P. Effect of fatty acids on energy coupling processes in mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1183:41-57. [PMID: 8399375 DOI: 10.1016/0005-2728(93)90004-y] [Citation(s) in RCA: 243] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Long-chain fatty acids are natural uncouplers of oxidative phosphorylation in mitochondria. The protonophoric mechanism of this action is due to transbilayer movement of undissociated fatty acid in one direction and the passage of its anion in the opposite direction. The transfer of the dissociated form of fatty acid can be, at least in some kinds of mitochondrion, facilitated by adenine nucleotide translocase. Apart from dissipating the electrochemical proton gradient, long-chain fatty acids decrease the activity of the respiratory chain by mechanism(s) not fully understood. In intact cells and tissues fatty acids operate mostly as excellent respiratory substrates, providing electrons to the respiratory chain. This function masks their potential uncoupling effect which becomes apparent only under special physiological or pathological conditions characterized by unusual fatty acid accumulation. Short- and medium-chain fatty acids do not have protonophoric properties. Nevertheless, they contribute to energy dissipation because of slow intramitochondrial hydrolysis of their activation products, acyl-AMP and acyl-CoA. Long-chain fatty acids increase permeability of mitochondrial membranes to alkali metal cations. This is due to their ionophoric mechanism of action. Regulatory function of fatty acids with respect to specific cation channels has been postulated for the plasma membrane of muscle cells, but not demonstrated in mitochondria. Under cold stress, cold acclimation and arousal from hibernation the uncoupling effect of fatty acids may contribute to increased thermogenesis, especially in the muscle tissue. In brown adipose tissue, the special thermogenic organ of mammals, long-chain fatty acids promote operation of the unique natural uncoupling protein, thermogenin. As anionic amphiphiles, long-chain fatty acids increase the negative surface charge of biomembranes, thus interfering in their enzymic and transporting functions.
Collapse
Affiliation(s)
- L Wojtczak
- Nencki Institute of Experimental Biology, Warsaw, Poland
| | | |
Collapse
|
7
|
Abstract
The activation of intramitochondrial dehydrogenases by Ca2+ provides a link between the intensity of work performance by a tissue and the activity of pyruvate dehydrogenase and the tricarboxylate cycle, and hence the rate of ATP production by the mitochondria. Several aspects of this model of the control of oxidative phosphorylation are examined in this article, with particular emphasis on mitochondrial functioning in situ in cardiac myocytes and in the intact heart. Recent use of the fluorescent Ca2+ chelating agents indo-1 and fura-2 has allowed a more quantitative description of the dependence of dehydrogenase activity upon concentration of free intramitochondrial Ca2+, in experiments with isolated mitochondria. Further, a novel technique developed by Miyata et al. has allowed description of free intramitochondrial Ca2+ within a single cardiac myocyte, and the conclusion that this parameter changes in response to electrical excitation of the cell over a range which would be expected to give substantial modulation of dehydrogenase activity.
Collapse
Affiliation(s)
- R G Hansford
- Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, Maryland 21224
| |
Collapse
|
8
|
Lai JC, Sheu KF. Relationship between activation state of pyruvate dehydrogenase complex and rate of pyruvate oxidation in isolated cerebro-cortical mitochondria: effects of potassium ions and adenine nucleotides. J Neurochem 1985; 45:1861-8. [PMID: 3840524 DOI: 10.1111/j.1471-4159.1985.tb10544.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The relation between the activation (phosphorylation) state of pyruvate dehydrogenase complex (PDHC; EC 1.2.4.1, EC 2.3.1.12, and EC 1.6.4.3) and the rate of pyruvate oxidation has been examined in isolated, metabolically active, and tightly coupled mitochondria from rat cerebral cortex. With pyruvate and malate as the substrates, the activation state of PDHC decreased on addition of ADP, while the rates of oxygen uptake and 14CO2 formation from [1-14C]pyruvate increased. The lack of correlation between the activation state of PDHC and rate of pyruvate oxidation was seen in media containing 5, 30, or 100 mM KCl. Both the activation state of PDHC and pyruvate oxidation increased, however, when KCl was increased from 5 to 100 mM. Although the PDHC is inactivated by an ATP-dependent kinase (EC 2.7.1.99), direct measurement of ATP and ADP failed to show a consistent relationship between the activation state of PDHC and either ATP levels or ATP/ADP ratios. Comparison of the activation state of PDHC in uncoupled or oligomycin-treated mitochondria also failed to correlate PDHC activation state to adenine nucleotides. In brain mitochondria, unlike those from other tissues, the activation state of PDHC does not seem to be related clearly to the rate of pyruvate oxidation, or to the mitochondrial adenylate energy charge.
Collapse
|
9
|
Wieland OH. The mammalian pyruvate dehydrogenase complex: structure and regulation. Rev Physiol Biochem Pharmacol 1983; 96:123-70. [PMID: 6338572 DOI: 10.1007/bfb0031008] [Citation(s) in RCA: 260] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
|
10
|
Patel TB, Debuysere MS, Scholz R, Olson MS. The regulation of the pyruvate dehydrogenase complex in the perfused rat liver: a role for the mitochondrial monocarboxylate translocator. Arch Biochem Biophys 1982; 213:573-84. [PMID: 6803675 DOI: 10.1016/0003-9861(82)90586-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
|
11
|
Zwiebel FM, Schwabe U, Olson MS, Scholz R. Role of pyruvate transporter in the regulation of the pyruvate dehydrogenase multienzyme complex in perfused rat liver. Biochemistry 1982; 21:346-53. [PMID: 7074018 DOI: 10.1021/bi00531a023] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Metabolic substrates such as octanoate, beta-hydroxybutyrate, and alpha-ketoisocaproate which produce acetoacetate stimulate the rate of pyruvate decarboxylation in perfused livers from fed rats at perfusate pyruvate concentrations in the physiological range (below 0.2 mM). A quantitative relationship between pyruvate oxidation (14CO2 production from [1-14C]pyruvate) and ketogenesis (production of acetoacetate or total ketone bodies) was observed with all ketogenic substrates when studied over a wide range of concentrations. The ratio of extra pyruvate decarboxylated to extra acetoacetate produced was greater than 1 with octanoate and alpha-ketoisocaproate, but it was less than 1 with beta-hydroxybutyrate. The stimulatory effect of beta-hydroxybutyrate on pyruvate decarboxylation was abolished completely in the presence of 0.1 mM alpha-cyanocinnamate, an inhibitor of the pyruvate transporting system in the mitochondrial membrane. The data suggest that the mechanism by which the flux through the pyruvate dehydrogenase reaction is stimulated in liver under ketogenic conditions involves an acceleration of the net rate of pyruvate transport into the mitochondria compartment due to an exchange with acetoacetate and/or acetoacetate plus beta-hydroxybutyrate.
Collapse
|
12
|
|
13
|
Davis-van Thienen W, Davis E. The effects of energetic steady state, pyruvate concentration, and octanoyl-(–)-carnitine on the relative rates of carboxylation and decarboxylation of pyruvate by rat liver mitochondria. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)68853-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
|
14
|
Chapter 9 Mitochondrial ion transport. ACTA ACUST UNITED AC 1981. [DOI: 10.1016/s0167-7306(08)60037-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
15
|
Wanders RJ, Van Woerkom GM, Nooteboom RF, Meijer AJ, Tager JM. Relationship between the rate of citrulline synthesis and bulk changes in the intramitochondrial ATP/ADP ratio in rat-liver mitochondria. EUROPEAN JOURNAL OF BIOCHEMISTRY 1981; 113:295-302. [PMID: 7202412 DOI: 10.1111/j.1432-1033.1981.tb05066.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
1. The relationship between intramitochondrial and extramitochondrial ATP-utilizing systems and the intramitochondrial ATP/ADP ratio was studied in isolated rat-liver mitochondria. Citrulline synthesis was used as an intramitochondrial ATP-utilizing system, and glucose-6-phosphate synthesis as an extramitochondrial ATP-utilizing system. The intramitochondrial ATP/ADP ratio was manipulated in three ways: with succinate and different concentrations of malonate and/or hexokinase; with 2-oxoglutarate (plus oligomycin) and different concentrations of hexokinase; and with added ATP in uncoupled mitochondria (oligomycin present). 2. Under all conditions used, citrulline synthesis was strictly correlated with the bulk intramitochondrial ATP/ADP ratio. 3. The curve relating citrulline synthesis and intramitochondrial ATP/ADP was shifted towards lower ATP/ADP ratios when the activity of carbamoyl-phosphate synthetase was enhanced by increasing the mitochondrial content of N-acetylglutamate. 4. It is concluded that under the experimental conditions used the intramitochondrial adenine nucleotides behave as a homogeneous pool.
Collapse
|
16
|
|
17
|
Studies of the effects of beta-adrenergic agonists on the regulation of pyruvate dehydrogenase in the perfused rat heart. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)43871-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
18
|
Effects of branched chain alpha-ketoacids on the metabolism of isolated rat liver cells. III. Interactions with pyruvate dehydrogenase. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)86189-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
19
|
|
20
|
Smith SJ, Saggerson ED. Regulation of pyruvate dehydrogenase activity in white adipocyte mitochondria by palmitoyl carnitine and citrate. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1979; 10:785-90. [PMID: 229006 DOI: 10.1016/0020-711x(79)90049-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
21
|
Hansford RG, Cohen L. Relative importance of pyruvate dehydrogenase interconversion and feed-back inhibition in the effect of fatty acids on pyruvate oxidation by rat heart mitochondria. Arch Biochem Biophys 1978; 191:65-81. [PMID: 216317 DOI: 10.1016/0003-9861(78)90068-1] [Citation(s) in RCA: 104] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
22
|
van Hinsbergh VW, Veerkamp JH, van Moerkerk HT. Palmitate oxidation by rat skeletal muscle mitochondria. Comparison of polarographic and radiochemical experiments. Arch Biochem Biophys 1978; 190:762-71. [PMID: 718176 DOI: 10.1016/0003-9861(78)90337-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
23
|
Olson M, Dennis S, DeBuysere M, Padma A. The regulation of pyruvate dehydrogenase in the isolated perfused rat heart. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(17)34510-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
24
|
Olson MS, Dennis SC, Routh CA, Debuysere MS. The regulation of pyruvate dehydrogenase by fatty acids in isolated rabbit heart mitochondria. Arch Biochem Biophys 1978; 187:121-31. [PMID: 207223 DOI: 10.1016/0003-9861(78)90014-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
25
|
Dennis S, DeBuysere M, Scholz R, Olson M. Studies on the relationship between ketogenesis and pyruvate oxidation in isolated rat liver mitochondria. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(17)38063-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
26
|
Ohlen J, Siess EA, Löffler G, Wieland OH. The effect of insulin on pyruvate dehydrogenase interconversion in heart muscle of alloxan-diabetic rats. Diabetologia 1978; 14:135-9. [PMID: 631458 DOI: 10.1007/bf01263452] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Evidence is presented for regulation by insulin of pyruvate dehydrogenase (pdh) interconversion in rat heart muscle in vivo and in vitro. In the alloxan diabetic rat the active (dephospho) enzyme amounted only to 12% of total PDH and was restored to 42% by insulin. Antilipolytic treatment of the dibetic animals was ineffective, indicating that the action of insulin was independent of a lowering of plasma non-esterified fatty acid concentration. On perfusion of isolated hearts from diabetic rats in the presence of glucose the proportion of pyruvate dehydrogenase in the active form remained low but was fully restored upon addition of insulin (2mU/ml) to the medium. No effect of insulin was obtained in the absence of glucose. The correlation between the rate of pyruvate decarboxylation in the perfused heart and of pyruvate dehydrogenase activity, in vitro, suggests that in the diabetic heart the entry of pyruvate into the citric acid cycle is largely controlled by covalent modification of the pyruvate dehydrogenase complex rather than by feedback inhibition. The possible role of insulin therein is discussed.
Collapse
|
27
|
Denton RM, Hughes WA. Pyruvate dehydrogenase and the hormonal regulation of fat synthesis in mammalian tissues. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1978; 9:545-52. [PMID: 213324 DOI: 10.1016/0020-711x(78)90113-1] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
28
|
Portenhauser R, Wieland OH, Wenzel H. Regulation of pyruvate dehydrogenase in heart mitochondria. HOPPE-SEYLER'S ZEITSCHRIFT FUR PHYSIOLOGISCHE CHEMIE 1977; 358:647-58. [PMID: 885486 DOI: 10.1515/bchm2.1977.358.1.647] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|