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Cai M, Li S, Cai K, Du X, Han J, Hu J. Empowering mitochondrial metabolism: Exploring L-lactate supplementation as a promising therapeutic approach for metabolic syndrome. Metabolism 2024; 152:155787. [PMID: 38215964 DOI: 10.1016/j.metabol.2024.155787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 12/08/2023] [Accepted: 01/05/2024] [Indexed: 01/14/2024]
Abstract
Mitochondrial dysfunction plays a critical role in the pathogenesis of metabolic syndrome (MetS), affecting various cell types and organs. In MetS animal models, mitochondria exhibit decreased quality control, characterized by abnormal morphological structure, impaired metabolic activity, reduced energy production, disrupted signaling cascades, and oxidative stress. The aberrant changes in mitochondrial function exacerbate the progression of metabolic syndrome, setting in motion a pernicious cycle. From this perspective, reversing mitochondrial dysfunction is likely to become a novel and powerful approach for treating MetS. Unfortunately, there are currently no effective drugs available in clinical practice to improve mitochondrial function. Recently, L-lactate has garnered significant attention as a valuable metabolite due to its ability to regulate mitochondrial metabolic processes and function. It is highly likely that treating MetS and its related complications can be achieved by correcting mitochondrial homeostasis disorders. In this review, we comprehensively discuss the complex relationship between mitochondrial function and MetS and the involvement of L-lactate in regulating mitochondrial metabolism and associated signaling pathways. Furthermore, it highlights recent findings on the involvement of L-lactate in common pathologies of MetS and explores its potential clinical application and further prospects, thus providing new insights into treatment possibilities for MetS.
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Affiliation(s)
- Ming Cai
- College of Rehabilitation Sciences, Shanghai University of Medicine and Health Sciences, Shanghai 201318, PR China; Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Shuyao Li
- College of Rehabilitation Sciences, Shanghai University of Medicine and Health Sciences, Shanghai 201318, PR China
| | - Keren Cai
- College of Rehabilitation Sciences, Shanghai University of Medicine and Health Sciences, Shanghai 201318, PR China
| | - Xinlin Du
- College of Rehabilitation Sciences, Shanghai University of Medicine and Health Sciences, Shanghai 201318, PR China
| | - Jia Han
- College of Rehabilitation Sciences, Shanghai University of Medicine and Health Sciences, Shanghai 201318, PR China.
| | - Jingyun Hu
- Central Lab, Shanghai Key Laboratory of Pathogenic Fungi Medical Testing, Shanghai Pudong New Area People's Hospital, Shanghai 201299, PR China.
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Kane DA, Foo ACY, Noftall EB, Brebner K, Marangoni DG. Lactate shuttling as an allostatic means of thermoregulation in the brain. Front Neurosci 2023; 17:1144639. [PMID: 37250407 PMCID: PMC10217782 DOI: 10.3389/fnins.2023.1144639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 04/18/2023] [Indexed: 05/31/2023] Open
Abstract
Lactate, the redox-balanced end product of glycolysis, travels within and between cells to fulfill an array of physiologic functions. While evidence for the centrality of this lactate shuttling in mammalian metabolism continues to mount, its application to physical bioenergetics remains underexplored. Lactate represents a metabolic "cul-de-sac," as it can only re-enter metabolism by first being converted back to pyruvate by lactate dehydrogenase (LDH). Given the differential distribution of lactate producing/consuming tissues during metabolic stresses (e.g., exercise), we hypothesize that lactate shuttling vis-à-vis the exchange of extracellular lactate between tissues serves a thermoregulatory function, i.e., an allostatic strategy to mitigate the consequences of elevated metabolic heat. To explore this idea, the rates of heat and respiratory oxygen consumption in saponin-permeabilized rat cortical brain samples fed lactate or pyruvate were measured. Heat and respiratory oxygen consumption rates, and calorespirometric ratios were lower during lactate vs. pyruvate-linked respiration. These results support the hypothesis of allostatic thermoregulation in the brain with lactate.
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Affiliation(s)
- Daniel A. Kane
- Department of Human Kinetics, St. Francis Xavier University, Antigonish, NS, Canada
| | - Alexander C. Y. Foo
- Department of Chemistry, St. Francis Xavier University, Antigonish, NS, Canada
| | - Erin B. Noftall
- Department of Human Kinetics, St. Francis Xavier University, Antigonish, NS, Canada
| | - Karen Brebner
- Department of Psychology, St. Francis Xavier University, Antigonish, NS, Canada
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Tracing the lactate shuttle to the mitochondrial reticulum. EXPERIMENTAL & MOLECULAR MEDICINE 2022; 54:1332-1347. [PMID: 36075947 PMCID: PMC9534995 DOI: 10.1038/s12276-022-00802-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 01/02/2022] [Accepted: 01/05/2022] [Indexed: 11/10/2022]
Abstract
Isotope tracer infusion studies employing lactate, glucose, glycerol, and fatty acid isotope tracers were central to the deduction and demonstration of the Lactate Shuttle at the whole-body level. In concert with the ability to perform tissue metabolite concentration measurements, as well as determinations of unidirectional and net metabolite exchanges by means of arterial–venous difference (a-v) and blood flow measurements across tissue beds including skeletal muscle, the heart and the brain, lactate shuttling within organs and tissues was made evident. From an extensive body of work on men and women, resting or exercising, before or after endurance training, at sea level or high altitude, we now know that Organ–Organ, Cell–Cell, and Intracellular Lactate Shuttles operate continuously. By means of lactate shuttling, fuel-energy substrates can be exchanged between producer (driver) cells, such as those in skeletal muscle, and consumer (recipient) cells, such as those in the brain, heart, muscle, liver and kidneys. Within tissues, lactate can be exchanged between white and red fibers within a muscle bed and between astrocytes and neurons in the brain. Within cells, lactate can be exchanged between the cytosol and mitochondria and between the cytosol and peroxisomes. Lactate shuttling between driver and recipient cells depends on concentration gradients created by the mitochondrial respiratory apparatus in recipient cells for oxidative disposal of lactate. Studies using isotope tracer technologies have significantly improved understanding of how lactate, a metabolite produced as fuel during normal metabolism and in response to exercise, moves or ‘shuttles’ throughout the body. George Brooks and colleagues at the University of California, Berkeley, USA, reviewed the history of the understanding of lactate shuttling, which has largely been informed by human studies using isotope tracer infusions during rest and exercise. Such research highlights continuous organ–organ, cell–cell, and intracellular lactate shuttling. Lactate moves between producer cells such as skeletal muscle cells and consumer cells in tissues including the heart and brain, where it is preferred over glucose as an energy source. Shuttling depends on lactate concentration gradients created by mitochondrial networks in recipient cells. Lactate is disposed of via oxidation.
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Hepatic Glucose Metabolism and Its Disorders in Fish. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1354:207-236. [PMID: 34807444 DOI: 10.1007/978-3-030-85686-1_11] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Carbohydrate, which is the most abundant nutrient in plant-sourced feedstuffs, is an economically indispensable component in commercial compound feeds for fish. This nutrient can enhance the physical quality of diets and allow for pellet expansion during extrusion. There is compelling evidence that an excess dietary intake of starch causes hepatic disorders, thereby further reducing the overall food consumption and growth performance of fish species. Among the severe metabolic disturbances are glycogenic hepatopathy (hepatomegaly caused by the excessive accumulation of glycogen in hepatocytes) and hepatic steatosis (the accumulation of large vacuoles of triacylglycerols in hepatocytes). The development of those disorders is mainly due to the limited ability of fish to oxidize glucose and control blood glucose concentration. The prolonged elevations of blood glucose increase glucose intake by the liver, and excess glucose is stored either as glycogen through glycogenesis in hepatocytes or as triglycerides via lipogenesis in tissues, depending on the species. In some fish species (e.g., largemouth bass), the liver has a low ability to regulate glycolysis, gluconeogenesis, and glycogen breakdown in response to high starch intake. For most species of fish, the liver size increases with lipid or glycogen accumulation when they have a high starch intake. It is a challenge to develop the same set of diagnostic criteria for all fish species as their physiology or metabolic patterns differ. Although glycogenic hepatopathy appears to be a common disease in carnivorous fish, it has been under-recognized in many studies. As a result, understanding these diseases and their pathogeneses in different fish species is crucial for manufacturing cost-effective pellet diets to promote the health, growth, survival, and feed efficiency of fish in future.
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Herbst EAF, George MAJ, Brebner K, Holloway GP, Kane DA. Lactate is oxidized outside of the mitochondrial matrix in rodent brain. Appl Physiol Nutr Metab 2017; 43:467-474. [PMID: 29206478 DOI: 10.1139/apnm-2017-0450] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The nature and existence of mitochondrial lactate oxidation is debated in the literature. Obscuring the issue are disparate findings in isolated mitochondria, as well as relatively low rates of lactate oxidation observed in permeabilized muscle fibres. However, respiration with lactate has yet to be directly assessed in brain tissue with the mitochondrial reticulum intact. To determine if lactate is oxidized in the matrix of brain mitochondria, oxygen consumption was measured in saponin-permeabilized mouse brain cortex samples, and rat prefrontal cortex and hippocampus (dorsal) subregions. While respiration in the presence of ADP and malate increased with the addition of lactate, respiration was maximized following the addition of exogenous NAD+, suggesting maximal lactate metabolism involves extra-matrix lactate dehydrogenase. This was further supported when NAD+-dependent lactate oxidation was significantly decreased with the addition of either low-concentration α-cyano-4-hydroxycinnamate or UK-5099, inhibitors of mitochondrial pyruvate transport. Mitochondrial respiration was comparable between glutamate, pyruvate, and NAD+-dependent lactate oxidation. Results from the current study demonstrate that permeabilized brain is a feasible model for assessing lactate oxidation, and support the interpretation that lactate oxidation occurs outside the mitochondrial matrix in rodent brain.
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Affiliation(s)
- Eric A F Herbst
- a Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Mitchell A J George
- b Department of Human Kinetics, St. Francis Xavier University, Antigonish, NS B2G 2W5, Canada
| | - Karen Brebner
- c Department of Psychology, St. Francis Xavier University, Antigonish, NS B2G 2W5, Canada
| | - Graham P Holloway
- a Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Daniel A Kane
- b Department of Human Kinetics, St. Francis Xavier University, Antigonish, NS B2G 2W5, Canada
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Elustondo PA, White AE, Hughes ME, Brebner K, Pavlov E, Kane DA. Physical and functional association of lactate dehydrogenase (LDH) with skeletal muscle mitochondria. J Biol Chem 2013; 288:25309-25317. [PMID: 23873936 PMCID: PMC3757195 DOI: 10.1074/jbc.m113.476648] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 07/09/2013] [Indexed: 11/06/2022] Open
Abstract
The intracellular lactate shuttle hypothesis posits that lactate generated in the cytosol is oxidized by mitochondrial lactate dehydrogenase (LDH) of the same cell. To examine whether skeletal muscle mitochondria oxidize lactate, mitochondrial respiratory oxygen flux (JO2) was measured during the sequential addition of various substrates and cofactors onto permeabilized rat gastrocnemius muscle fibers, as well as isolated mitochondrial subpopulations. Addition of lactate did not alter JO2. However, subsequent addition of NAD(+) significantly increased JO2, and was abolished by the inhibitor of mitochondrial pyruvate transport, α-cyano-4-hydroxycinnamate. In experiments with isolated subsarcolemmal and intermyofibrillar mitochondrial subpopulations, only subsarcolemmal exhibited NAD(+)-dependent lactate oxidation. To further investigate the details of the physical association of LDH with mitochondria in muscle, immunofluorescence/confocal microscopy and immunoblotting approaches were used. LDH clearly colocalized with mitochondria in intact, as well as permeabilized fibers. LDH is likely localized inside the outer mitochondrial membrane, but not in the mitochondrial matrix. Collectively, these results suggest that extra-matrix LDH is strategically positioned within skeletal muscle fibers to functionally interact with mitochondria.
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Affiliation(s)
- Pia A Elustondo
- From the Department of Physiology and Biophysics, Dalhousie University, Halifax, NS B3H 4R2 and
| | | | | | - Karen Brebner
- Psychology, St. Francis Xavier University, Antigonish, Nova Scotia B2G 2W5, Canada
| | - Evgeny Pavlov
- From the Department of Physiology and Biophysics, Dalhousie University, Halifax, NS B3H 4R2 and
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Carazo A, Levin J, Casas F, Seyer P, Grandemange S, Busson M, Pessemesse L, Wrutniak-Cabello C, Cabello G. Protein sequences involved in the mitochondrial import of the 3,5,3′-L-triiodothyronine receptor p43. J Cell Physiol 2012; 227:3768-77. [DOI: 10.1002/jcp.24085] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Cruz RSDO, de Aguiar RA, Turnes T, Penteado Dos Santos R, Fernandes Mendes de Oliveira M, Caputo F. Intracellular shuttle: the lactate aerobic metabolism. ScientificWorldJournal 2012; 2012:420984. [PMID: 22593684 PMCID: PMC3345575 DOI: 10.1100/2012/420984] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 11/12/2011] [Indexed: 11/17/2022] Open
Abstract
Lactate is a highly dynamic metabolite that can be used as a fuel by several cells of the human body, particularly during physical exercise. Traditionally, it has been believed that the first step of lactate oxidation occurs in cytosol; however, this idea was recently challenged. A new hypothesis has been presented based on the fact that lactate-to-pyruvate conversion cannot occur in cytosol, because the LDH enzyme characteristics and cytosolic environment do not allow the reaction in this way. Instead, the Intracellular Lactate Shuttle hypothesis states that lactate first enters in mitochondria and only then is metabolized. In several tissues of the human body this idea is well accepted but is quite resistant in skeletal muscle. In this paper, we will present not only the studies which are protagonists in this discussion, but the potential mechanism by which this oxidation occurs and also a link between lactate and mitochondrial proliferation. This new perspective brings some implications and comes to change our understanding of the interaction between the energy systems, because the product of one serves as a substrate for the other.
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Affiliation(s)
| | | | | | | | | | - Fabrizio Caputo
- Human Performance Research Group, Center of Health and Sport Sciences, Santa Catarina State University, 88080-350 Florianópolis, SC, Brazil
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Ling B, Peng F, Alcorn J, Lohmann K, Bandy B, Zello GA. D-Lactate altered mitochondrial energy production in rat brain and heart but not liver. Nutr Metab (Lond) 2012; 9:6. [PMID: 22296683 PMCID: PMC3292964 DOI: 10.1186/1743-7075-9-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 02/01/2012] [Indexed: 11/24/2022] Open
Abstract
Background Substantially elevated blood D-lactate (DLA) concentrations are associated with neurocardiac toxicity in humans and animals. The neurological symptoms are similar to inherited or acquired abnormalities of pyruvate metabolism. We hypothesized that DLA interferes with mitochondrial utilization of L-lactate and pyruvate in brain and heart. Methods Respiration rates in rat brain, heart and liver mitochondria were measured using DLA, LLA and pyruvate independently and in combination. Results In brain mitochondria, state 3 respiration was 53% and 75% lower with DLA as substrate when compared with LLA and pyruvate, respectively (p < 0.05). Similarly in heart mitochondria, state 3 respiration was 39% and 86% lower with DLA as substrate when compared with LLA or pyruvate, respectively (p < 0.05). However, state 3 respiration rates were similar between DLA, LLA and pyruvate in liver mitochondria. Combined incubation of DLA with LLA or pyruvate markedly impaired state 3 respiration rates in brain and heart mitochondria (p < 0.05) but not in liver mitochondria. DLA dehydrogenase activities were 61% and 51% lower in brain and heart mitochondria compared to liver, respectively, whereas LLA dehydrogenase activities were similar across all three tissues. An LDH inhibitor blocked state 3 respiration with LLA as substrate in all three tissues. A monocarboxylate transporter inhibitor blocked respiration with all three substrates. Conclusions DLA was a poor respiratory substrate in brain and heart mitochondria and inhibited LLA and pyruvate usage in these tissues. Further studies are warranted to evaluate whether these findings support, in part, the possible neurological and cardiac toxicity caused by high DLA levels.
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Affiliation(s)
- Binbing Ling
- College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, Canada.
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Abstract
Lactate production in skeletal muscle has now been studied for nearly two centuries and still its production and functional role at rest and during exercise is much debated. In the early days skeletal muscle was mainly seen as the site of lactate production during contraction and lactate production associated with a lack of muscle oxygenation and fatigue. Later it was recognized that skeletal muscle not only played an important role in lactate production but also in lactate clearance and this led to a renewed interest, not the least from the Copenhagen School in the 1930s, in the metabolic role of lactate in skeletal muscle. With the introduction of lactate isotopes muscle lactate kinetics and oxidation could be studied and a simultaneous lactate uptake and release was observed, not only in muscle but also in other tissues. Therefore, this review will discuss in vivo human: (1) skeletal muscle lactate metabolism at rest and during exercise and suggestions are put forward to explain the simultaneous lactate uptake and release; and (2) lactate metabolism in the heart, liver, kidneys, brain, adipose tissue and lungs will be discussed and its potential importance in these tissues.
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Affiliation(s)
- Gerrit van Hall
- Metabolic Mass-Spectrometry Facility, Rigshospitalet and Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
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11
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Mitochondria andl-lactate metabolism. FEBS Lett 2008; 582:3569-76. [DOI: 10.1016/j.febslet.2008.09.042] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 09/16/2008] [Accepted: 09/22/2008] [Indexed: 11/18/2022]
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Abstract
This year, 2008, marks the bicentennial of research into lactate metabolism in muscle. Berzelius linked lactate accumulation to exercise in 1807/1808 when he noted the presence of lactate in the muscles of "hunted stags." Today, the exact mechanism of intramuscular lactate oxidation and the relationship of lactate dehydrogenase to mitochondria remain unresolved as animated debate surrounds the intracellular lactate shuttle.
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Abstract
The cell-to-cell lactate shuttle was introduced in 1984 and has been repeatedly supported by studies using a variety of experimental approaches. Because of its large mass and metabolic capacity, skeletal muscle is probably the major component of the lactate shuttle in terms of both production and consumption. Muscles exercising in a steady state are avid consumers of lactate, using most of the lactate as an oxidative fuel. Cardiac muscle is highly oxidative and readily uses lactate as a fuel. Lactate is a major gluconeogenic substrate for the liver; the use of lactate to form glucose increases when blood lactate concentration is elevated. Illustrative of the widespread shuttling of lactate, even the brain takes up lactate when the blood level is increased. Recently, an intracellular lactate shuttle has also been proposed. Although disagreements abound, current evidence suggests that lactate is the primary end-product of glycolysis at cellular sites remote from mitochondria. This lactate could subsequently diffuse to areas adjacent to mitochondria. Evidence is against lactate oxidation within the mitochondrial matrix, but a viable hypothesis is that lactate could be converted to pyruvate by a lactate oxidation complex with lactate dehydrogenase located on the outer surface of the inner mitochondrial membrane. In another controversial area, the role of lactic acid in acid-base balance has been hotly debated in recent times. Careful analysis reveals that lactate, not lactic acid, is the substrate/product of metabolic reactions. One view is that lactate formation alleviates acidosis, whereas another is that lactate is a causative factor in acidosis. Surprisingly, there is little direct mechanistic evidence regarding cause and effect in acid-base balance. However, there is insufficient evidence to discard the term "lactic acidosis."
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Affiliation(s)
- L Bruce Gladden
- Department of Kinesiology, Auburn University, Auburn, AL 36849-5323, USA.
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Atlante A, de Bari L, Bobba A, Marra E, Passarella S. Transport and metabolism of L-lactate occur in mitochondria from cerebellar granule cells and are modified in cells undergoing low potassium dependent apoptosis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:1285-99. [PMID: 17950241 DOI: 10.1016/j.bbabio.2007.08.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Revised: 07/24/2007] [Accepted: 08/20/2007] [Indexed: 10/22/2022]
Abstract
Having confirmed that externally added L-lactate can enter cerebellar granule cells, we investigated whether and how L-lactate is metabolized by mitochondria from these cells under normal or apoptotic conditions. (1) L-lactate enters mitochondria, perhaps via an L-lactate/H+ symporter, and is oxidized in a manner stimulated by ADP. The existence of an L-lactate dehydrogenase, located in the inner mitochondrial compartment, was shown by immunological analysis. Neither the protein level nor the Km and Vmax values changed en route to apoptosis. (2) In both normal and apoptotic cell homogenates, externally added L-lactate caused reduction of the intramitochondrial pyridine cofactors, inhibited by phenylsuccinate. This process mirrored L-lactate uptake by mitochondria and occurred with a hyperbolic dependence on L-lactate concentrations. Pyruvate appeared outside mitochondria as a result of external addition of L-lactate. The rate of the process depended on L-lactate concentration and showed saturation characteristics. This shows the occurrence of an intracellular L-lactate/pyruvate shuttle, whose activity was limited by the putative L-lactate/pyruvate antiporter. Both the carriers were different from the monocarboxylate carrier. (3) L-lactate transport changed en route to apoptosis. Uptake increased in the early phase of apoptosis, but decreased in the late phase with characteristics of a non-competitive like inhibition. In contrast, the putative L-lactate/pyruvate antiport decreased en route to apoptosis with characteristics of a competitive like inhibition in early apoptosis, and a mixed non-competitive like inhibition in late apoptosis.
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Affiliation(s)
- Anna Atlante
- Istituto di Biomembrane e Bioenergetica, Consiglio Nazionale delle Ricerche, Via G Amendola, 165/A-70126, Bari, Italy.
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Schurr A, Payne RS. Lactate, not pyruvate, is neuronal aerobic glycolysis end product: An in vitro electrophysiological study. Neuroscience 2007; 147:613-9. [PMID: 17560727 DOI: 10.1016/j.neuroscience.2007.05.002] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Revised: 04/30/2007] [Accepted: 05/01/2007] [Indexed: 10/23/2022]
Abstract
For over 60 years, a distinction has been made between aerobic and anaerobic glycolysis based on their respective end products: pyruvate of the former, lactate of the latter. Recently we hypothesized that, in the brain, both aerobic and anaerobic glycolysis terminate with the formation of lactate from pyruvate by the enzyme lactate dehydrogenase (LDH). If this hypothesis is correct, lactate must be the mitochondrial substrate for oxidative energy metabolism via its oxidation to pyruvate, plausibly by a mitochondrial LDH. Here we employed electrophysiology of the rat hippocampal slice preparation to test and monitor the effects of malonate and oxamate, two different LDH inhibitors, and glutamate, a neuronal activator, in experiments, the results of which support the hypothesis that lactate, at least in this in vitro setting, is indeed the principal end product of neuronal aerobic glycolysis.
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Affiliation(s)
- A Schurr
- Department of Anesthesiology and Perioperative Medicine, University of Louisville, School of Medicine, Louisville, KY 40202, USA.
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Yoshida Y, Holloway GP, Ljubicic V, Hatta H, Spriet LL, Hood DA, Bonen A. Negligible direct lactate oxidation in subsarcolemmal and intermyofibrillar mitochondria obtained from red and white rat skeletal muscle. J Physiol 2007; 582:1317-35. [PMID: 17556391 PMCID: PMC2075251 DOI: 10.1113/jphysiol.2007.135095] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We examined the controversial notion of whether lactate is directly oxidized by subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria obtained from red and white rat skeletal muscle. Respiratory control ratios were normal in SS and IMF mitochondria. At all concentrations (0.18-10 mm), and in all mitochondria, pyruvate oxidation greatly exceeded lactate oxidation, by 31- to 186-fold. Pyruvate and lactate oxidation were inhibited by alpha-cyano-4-hydroxycinnamate, while lactate oxidation was inhibited by oxamate. Excess pyruvate (10 mm) inhibited the oxidation of palmitate (1.8 mm) as well as lactate (1.8 mm). In contrast, excess lactate (10 mm) failed to inhibit the oxidation of either palmitate (1.8 mm) or pyruvate (1.8 mm). The cell-permeant adenosine analogue, AICAR, increased pyruvate oxidation; in contrast, lactate oxidation was not altered. The monocarboxylate transporters MCT1 and 4 were present on SS mitochondria, but not on IMF mitochondria, whereas, MCT2, a high-affinity pyruvate transporter, was present in both SS and IMF mitochondria. The lactate dehydrogenase (LDH) activity associated with SS and IMF mitochondria was 200- to 240-fold lower than in whole muscle. Addition of LDH increased the rate of lactate oxidation, but not pyruvate oxidation, in a dose-dependent manner, such that lactate oxidation approached the rates of pyruvate oxidation. Collectively, these studies indicate that direct mitochondrial oxidation of lactate (i.e. an intracellular lactate shuttle) does not occur within the matrix in either IMF or SS mitochondria obtained from red or white rat skeletal muscle, because of the very limited quantity of LDH within mitochondria.
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Affiliation(s)
- Yuko Yoshida
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Yahong C, Ruxiu C. Highly sensitive fluorimetic determination of gluthione based inhibitory effect on multienzyme redox system. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2005; 61:3051-5. [PMID: 16165050 DOI: 10.1016/j.saa.2004.11.041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Accepted: 11/17/2004] [Indexed: 05/04/2023]
Abstract
A highly sensitive spectrofluorimetric method for the determination of reduced glutathione (GSH,gamma-L-glutamyl-L-cysteinylglycine) based on its inhibitory effect on hemoglobin activity was developed. Multienzyme redox system is the most important biological oxidation process in cellular respiration chain. Under the action of hemoglobin, NADH can be oxidized by hydrogen peroxide (H2O2) to form a dimmer that is optimally fluorescent. Under the optimum conditions, the degree of inhibitory effect was linear to the GSH concentration in the range of 5.00 x 10(-8) to 9.60 x 10(-6) mol l(-1). The relative standard deviation was 3.70% for 11 determinations of 5.00 x 10(-6) mol l(-1) GSH and the detection limit was 8.00 x 10(-9) mol l(-1). Further experimental results revealed that the inhibition of GSH on this system was of the competitive type.
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Affiliation(s)
- Chen Yahong
- Suzhou Center for Disease Control and Prevention, Suzhou 215003, Wuhan University, Wuhan 430072, PR China
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18
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Abstract
For much of the 20th century, lactate was largely considered a dead-end waste product of glycolysis due to hypoxia, the primary cause of the O2 debt following exercise, a major cause of muscle fatigue, and a key factor in acidosis-induced tissue damage. Since the 1970s, a 'lactate revolution' has occurred. At present, we are in the midst of a lactate shuttle era; the lactate paradigm has shifted. It now appears that increased lactate production and concentration as a result of anoxia or dysoxia are often the exception rather than the rule. Lactic acidosis is being re-evaluated as a factor in muscle fatigue. Lactate is an important intermediate in the process of wound repair and regeneration. The origin of elevated [lactate] in injury and sepsis is being re-investigated. There is essentially unanimous experimental support for a cell-to-cell lactate shuttle, along with mounting evidence for astrocyte-neuron, lactate-alanine, peroxisomal and spermatogenic lactate shuttles. The bulk of the evidence suggests that lactate is an important intermediary in numerous metabolic processes, a particularly mobile fuel for aerobic metabolism, and perhaps a mediator of redox state among various compartments both within and between cells. Lactate can no longer be considered the usual suspect for metabolic 'crimes', but is instead a central player in cellular, regional and whole body metabolism. Overall, the cell-to-cell lactate shuttle has expanded far beyond its initial conception as an explanation for lactate metabolism during muscle contractions and exercise to now subsume all of the other shuttles as a grand description of the role(s) of lactate in numerous metabolic processes and pathways.
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Affiliation(s)
- L B Gladden
- Department of Health and Human Performance, 2050 Memorial Coliseum, Auburn University, Auburn, AL 36849-5323, USA.
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19
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Rasmussen HN, van Hall G, Rasmussen UF. Lactate dehydrogenase is not a mitochondrial enzyme in human and mouse vastus lateralis muscle. J Physiol 2002; 541:575-80. [PMID: 12042361 PMCID: PMC2290332 DOI: 10.1113/jphysiol.2002.019216] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2002] [Accepted: 04/18/2002] [Indexed: 11/08/2022] Open
Abstract
The presence of lactate dehydrogenase in skeletal muscle mitochondria was investigated to clarify whether lactate is a possible substrate for mitochondrial respiration. Mitochondria were prepared from 100 mg samples of human and mouse vastus lateralis muscle. All fractions from the preparation procedure were assayed for marker enzymes and lactate dehydrogenase (LDH). The mitochondrial fraction contained no LDH activity (detection limit approximately 0.05 % of the tissue activity) and the distribution of LDH activity among the fractions paralleled that of pyruvate kinase, i.e. LDH was fractionated as a cytoplasmic enzyme. Respiratory experiments with the mitochondrial fraction also indicated the absence of LDH. Lactate did not cause respiration, nor did it affect the respiration of pyruvate + malate. The major part of the native cytochrome c was retained in the isolated mitochondria, which, furthermore, showed high specific rates of state 3 respiration. This excluded artificial loss from the mitochondria of all activity of a possible LDH. It was concluded that skeletal muscle mitochondria are devoid of LDH and unable to metabolize lactate.
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Affiliation(s)
- Hans N Rasmussen
- Department of Biochemistry, August Krogh Institute, University of Copenhagen, Universitetsparken 13, DK-2100, Copenhagen Ø, Denmark.
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20
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McClelland GB, Brooks GA. Changes in MCT 1, MCT 4, and LDH expression are tissue specific in rats after long-term hypobaric hypoxia. J Appl Physiol (1985) 2002; 92:1573-84. [PMID: 11896024 DOI: 10.1152/japplphysiol.01069.2001] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Little is known about the effect of chronic hypobaric hypoxia on the enzymes and transporters involved in lactate metabolism. We looked at the protein expression of monocarboxylate transporters MCT 1, MCT 2, and MCT 4, along with total lactate dehydrogenase (LDH) and LDH isozymes in skeletal muscle, cardiac muscle, and liver. Expression of these components of the lactate shuttle affects the ability to transport and oxidize lactate. We hypothesized that the expression of MCTs and LDH would increase after acclimation to high altitude (HA). The response to acclimation to HA was, however, tissue specific. In addition, the response was different in whole muscle (Mu) and mitochondria-enriched (Mi) fractions. Heart, soleus, and plantaris muscles showed the greatest response to HA. Acclimation resulted in a 34% increase in MCT 4 in heart and a decrease in MCT 1 (-47%) and MCT 4 (-47%) in plantaris Mu. In Mi fractions, the heart had an increase (+40%) and soleus a decrease (-40%) in LDH. HA also had a significant effect on the LDH isozyme composition of both the Mu and Mi fractions. Mitochondrial density was decreased in both the soleus (-17%) and plantaris (-44%) as a result of chronic hypoxia. We conclude that chronic hypoxia had a tissue-specific effect on MCTs and LDH (that form the lactate shuttle) but did not produce a consistent increase in these components in all tissues.
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Affiliation(s)
- Grant B McClelland
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California 94720-3140, USA
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21
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Abstract
Lactate production in skeletal muscle has now been studied for nearly two centuries and still its production and functional role at rest and during muscle contraction is a subject of debate. Historically, skeletal muscle was seen mainly as the site of lactate production during contraction and lactate production associated with a lack of muscle oxygenation and fatigue. Later, it was recognized that skeletal muscle not only plays an important role in lactate production but also in lactate clearance and this in turn has led to a renewed interest in the metabolic fate of lactate in skeletal muscle and also in other tissues. Studies using lactate isotopes have shown that skeletal muscle extracts lactate from the circulation despite a substantial net lactate release, and that skeletal muscle has a large capacity for lactate oxidation; these processes being enhanced with exercise. Lactate dehydrogenase (LDH) controls the formation of lactate and may regulate the turnover of lactate in the muscle cell. Skeletal muscle contains five LDH isoforms (LDH1-5). Of the five LDH isoforms, the heart-specific LDH1, 2 is generally suggested to favour the reaction of lactate to pyruvate whereas the muscle-specific LDH4,5 isoform favours lactate formation. However, in this paper, it is argued that compartmentalization of the muscle cell and LDH association with cell structures may play a more predominant role in whether the LDH reaction proceeds towards lactate or pyruvate formation. The model for skeletal muscle lactate metabolism presented is in essence based on a synthesis of old and more recent studies on skeletal muscle lactate transport, uptake, release, oxidation, and the role of LDH at rest and during exercise.
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Affiliation(s)
- G Van Hall
- The Copenhagen Muscle Research Centre, Rigshospitalet, Copenhagen, Denmark
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22
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Nakae Y, Stoward PJ. Effects of tissue protectants on the kinetics of lactate dehydrogenase in cells. J Histochem Cytochem 1997; 45:1417-25. [PMID: 9313803 DOI: 10.1177/002215549704501010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We studied the effects of two tissue protectants, polyvinyl alcohol (PVA) and agarose gel, on a kinetic parameter of lactate dehydrogenase LDH that is assumed to be related to the extent of diffusion of the enzyme out of tissue sections during its histochemical assay. the kinetics of the enzyme in mouse gastrocnemius (skeletal) muscle fibers and periportal hepatocytes were determined in unfixed sections incubated either on substrate (L-lactate)-containing agarose gel films or in aqueous assay media in the presence or absence of 18% PVA. The absorbances of the formazan final reaction products at their isobestic point were measured continuously in the cytoplasm of individual cells as a function of incubation time, using a real-time image analysis system. Whichever incubation medium was used, the absorbances in the two cell types increased nonlinearly during the first minute of incubation but linearly for incubation times between 1 and 3 min. The nonlinearity of the LDH reaction was analyzed using the equation vi-v = a0A, where vi is the observed initial velocity determined from the absorbance changes during the first 10 sec of incubation and v and 0 A are respectively the gradient and intercept on the absorbance axis of the linear regression line of the absorbance on incubation times between 1 and 3 min. The plots of the observed (vi-v) against 0 A were linear. Their gradients a were characteristic for each cell type and tissue protectant. The a values for skeletal muscle fibers were 12-43% lower than those for hepatocytes. The a value for hepatocytes obtained with the PVA method was 32% lower than that determined with the gel film method. For skeletal muscle fibers, the a values determined by the two methods were almost the same. Addition of excess pyruvate to the aqueous assay medium had no effects on a for either muscle fibers or hepatocytes. In contrast, a was zero for sections of polyacrylamide gels containing purified enzyme, whether incubated on agarose films or in PVA media. These data confirmed that the constant a is related to the extent to which the enzyme diffuses out of sections during incubation but not to product inhibition of LDH by pyruvate. PVA was more effective for protecting diffusion of LDH from hepatocytes than from skeletal muscle fibers, possibly because hepatocytes contain a greater proportion of diffusable (unbound) LDH than skeletal muscle fibers.
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Affiliation(s)
- Y Nakae
- Department of Oral Anatomy 1, Tokushima University School of Dentistry, Japan
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23
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Stavropoulos G, Magafa V, Liakopoulou-Kyriakides M, Sinakos Z, Aaberg A. Synthesis of salicyl-peptides and their effect on human platelet aggregationin vitro. Amino Acids 1997. [DOI: 10.1007/bf01373215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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24
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Heavner GA. Active sequences in cell adhesion molecules: targets for therapeutic intervention. Drug Discov Today 1996. [DOI: 10.1016/1359-6446(96)10027-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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25
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Vegners R, Shestakova I, Kalvinsh I, Ezzell RM, Janmey PA. Use of a gel-forming dipeptide derivative as a carrier for antigen presentation. J Pept Sci 1995; 1:371-8. [PMID: 9223016 DOI: 10.1002/psc.310010604] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A dipeptide of the formula Fmoc-Leu-Asp and some other related dipeptides were synthesized in solution by standard methods. When such peptides are dissolved in water at concentrations below 1% at 100 degrees C and cooled below 60 degrees C they form turbid solutions and eventually viscoelastic gels at lower temperatures. Such gels are thermoreversible and can also be disrupted by mechanical agitation. At a concentration of 2 mg/ml the peptide Fmoc-Leu-Asp forms an aqueous gel at 60 degrees C with a shear modulus of 80 Pa measured at a frequency of 1 rad/s. Peptide solutions undergo an abrupt increase in light scattering between 1 and 1.5 mg/ml at both 23 and 60 degrees C. By analogy with previous observations of other systems, this increase appears to be due to the formation of filamentous micelles and the aggregation of filaments into a three-dimensional network. When low molecular weight adamantanamine derivatives, which are inherently non-antigenic antiviral drugs, were incorporated into the Fmoc-Leu-Asp gel and injected into rabbits, high titre specific antibodies were efficiently produced without the need for additional adjuvant. Both the physical properties of the gel and its effect on the antigenicity of low molecular weight compounds suggest a number of practical applications.
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Affiliation(s)
- R Vegners
- Latvian Institute of Organic Synthesis, Riga, Latvia
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26
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Wrutniak C, Cassar-Malek I, Marchal S, Rascle A, Heusser S, Keller JM, Fléchon J, Dauça M, Samarut J, Ghysdael J. A 43-kDa protein related to c-Erb A alpha 1 is located in the mitochondrial matrix of rat liver. J Biol Chem 1995; 270:16347-54. [PMID: 7608204 DOI: 10.1074/jbc.270.27.16347] [Citation(s) in RCA: 165] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
In order to characterize Sterling's triiodothyronine (T3) mitochondrial receptor using photoaffinity labeling, we observed two specific T3-binding proteins in the inner membrane (28 kDa) and in the matrix (43 kDa) of rat liver mitochondria. Western blots and immunoprecipitation using antibodies raised against the T3-binding domain of the T3 nuclear receptor c-Erb A alpha 1 indicated that at least the 43-kDa protein was c-Erb A alpha 1-related. In addition, gel mobility shift assays demonstrated the occurrence of a c-Erb A alpha 1-related mitochondrial protein that specifically binds to a natural or a palindromic thyroid-responsive element. Moreover, this protein specifically binds to a direct repeat 2 sequence located in the D-loop of the mitochondrial genome. Furthermore, electron microscopy studies allowed the direct observation of a c-Erb A-related protein in mitochondria. Lastly, the relative amounts of the 43-kDa protein related to c-Erb A alpha 1 were in good correlation with the known mitochondrial mass in three typical tissues. Interestingly, expression of a truncated form of the c-Erb A alpha 1 nuclear receptor in CV1 cells was associated with a mitochondrial localization and a stimulation of mitochondrial activity. These results supply evidence of the localization of a member of the nuclear receptor superfamily in the mitochondrial matrix involved in the regulation of mitochondrial activity that could act as a mitochondrial T3-dependent transcription factor.
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Affiliation(s)
- C Wrutniak
- Laboratoire de Différenciation Cellulaire et Croissance, Institut National de la Recherche Agronomique (INRA), Montpellier, France
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Nakae Y, Stoward PJ. The initial reaction velocities of lactate dehydrogenase in various cell types. THE HISTOCHEMICAL JOURNAL 1994; 26:283-91. [PMID: 8040001 DOI: 10.1007/bf00157760] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The initial reaction velocities (vi) of lactate dehydrogenase in hepatocytes, cardiac muscle fibres, skeletal (gastrocnemius) muscle fibres, gastric parietal cells, ductal epithelial and acinar cells of the parotid gland, and oocytes were determined, by computer-assisted image analysis, in unfixed sections of these tissues incubated at 37 degrees C on substrate-containing agarose gel films. They were found to fit the equations vi = a1 zero A (equation 1) and vi-v = a2 zero A (equation 2) reported previously for mouse hepatocytes (Nakae & Stoward, 1993a, b), where v and zero A are, respectively, the gradients (or steady-state velocities) and the intercepts on the absorbance axis of the linear regression lines of the absorbance (A) of the final reaction product on incubation times between 1 and 3 min, and a1 and a2 are constants. Both equations 1 and 2 fitted the observed vi closely for mouse (a1 = 2.7, a2 = 2.2) and human (a1 = 3.0, a2 = 1.9) hepatocytes. However, equation 2 fitted the observed vi better than equation 1 for mouse cardiac muscle fibres (a1 = 1.5), skeletal muscle fibres (a2 = 1.2), gastric parietal cells (a2 = 1.7), acinar (a2 = 1.4) and striated ductal (a2 = 2.2) epithelial cells of the parotid gland, and oocytes (a2 = 1.6). The values of vi calculated from the two equations agreed with the observed vi to within about 11%. They ranged from 105 mumole hydrogen equivalents/cm3 cell/min units in hepatocytes to 24 units in parotid acinar cells, but for other cell types they were between 46 and 61 units. These are all considerably higher than values reported previously.
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Affiliation(s)
- Y Nakae
- Department of Oral Anatomy, School of Dentistry, Tokushima University, Japan
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28
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Szczesna-Kaczmarek A. Regulating effect of mitochondrial lactate dehydrogenase on oxidation of cytoplasmic NADH via an "external" pathway in skeletal muscle mitochondria. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1992; 24:657-61. [PMID: 1516736 DOI: 10.1016/0020-711x(92)90343-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
1. The specific activity of lactate dehydrogenase of skeletal muscle mitochondria was found to be 2.5 times lower than specific activity of total NADH-cytochrome c reductase. 2. The specific activity of mitochondrial LDH in skeletal muscle mitochondria was almost equal to the activity of rotenone-insensitive NADH-cytochrome c reductase. 3. Mitochondrial LDH acting as an oxidase of lactate to pyruvate may feed an "external" pathway, but the activity of the mitochondrial enzyme is a limiting factor in oxidation of lactate-derived NADH. 4. Mitochondrial LDH acting as a reductase of pyruvate to lactate successfully competes with an "external" pathway for cytoplasmic NADH. 5. Exogenous NADH oxidation via an "external" pathway was inhibited by pyruvic acid. This inhibition was overcome by addition of oxamic acid or hydrazine.
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Affiliation(s)
- A Szczesna-Kaczmarek
- Department of Physiology, Jedrzej Sniadecki Academy of Physical Education, Gdańsk-Oliwa, Poland
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