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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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2
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Schurr A. How the 'Aerobic/Anaerobic Glycolysis' Meme Formed a 'Habit of Mind' Which Impedes Progress in the Field of Brain Energy Metabolism. Int J Mol Sci 2024; 25:1433. [PMID: 38338711 PMCID: PMC10855259 DOI: 10.3390/ijms25031433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 01/20/2024] [Accepted: 01/22/2024] [Indexed: 02/12/2024] Open
Abstract
The division of glycolysis into two separate pathways, aerobic and anaerobic, depending on the presence or absence of oxygen, respectively, was formulated over eight decades ago. The former ends with pyruvate, while the latter ends with lactate. Today, this division is confusing and misleading as research over the past 35 years clearly has demonstrated that glycolysis ends with lactate not only in cancerous cells but also in healthy tissues and cells. The present essay offers a review of the history of said division and the more recent knowledge that has been gained about glycolysis and its end-product, lactate. Then, it presents arguments in an attempt to explain why separating glycolysis into aerobic and anaerobic pathways persists among scientists, clinicians and teachers alike, despite convincing evidence that such division is not only wrong scientifically but also hinders progress in the field of energy metabolism.
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Affiliation(s)
- Avital Schurr
- Department of Anesthesiology and Perioperative Medicine, University of Louisville School of Medicine, Louisville, KY 40202, USA
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3
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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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4
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Li X, Yang Y, Zhang B, Lin X, Fu X, An Y, Zou Y, Wang JX, Wang Z, Yu T. Lactate metabolism in human health and disease. Signal Transduct Target Ther 2022; 7:305. [PMID: 36050306 PMCID: PMC9434547 DOI: 10.1038/s41392-022-01151-3] [Citation(s) in RCA: 242] [Impact Index Per Article: 121.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Revised: 07/17/2022] [Accepted: 08/09/2022] [Indexed: 12/29/2022] Open
Abstract
The current understanding of lactate extends from its origins as a byproduct of glycolysis to its role in tumor metabolism, as identified by studies on the Warburg effect. The lactate shuttle hypothesis suggests that lactate plays an important role as a bridging signaling molecule that coordinates signaling among different cells, organs and tissues. Lactylation is a posttranslational modification initially reported by Professor Yingming Zhao’s research group in 2019. Subsequent studies confirmed that lactylation is a vital component of lactate function and is involved in tumor proliferation, neural excitation, inflammation and other biological processes. An indispensable substance for various physiological cellular functions, lactate plays a regulatory role in different aspects of energy metabolism and signal transduction. Therefore, a comprehensive review and summary of lactate is presented to clarify the role of lactate in disease and to provide a reference and direction for future research. This review offers a systematic overview of lactate homeostasis and its roles in physiological and pathological processes, as well as a comprehensive overview of the effects of lactylation in various diseases, particularly inflammation and cancer.
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Affiliation(s)
- Xiaolu Li
- Center for Regenerative Medicine, Institute for Translational Medicine, The Affiliated Hospital of Qingdao University; Department of Cardiac Ultrasound, The Affiliated Hospital of Qingdao University, No. 16 Jiangsu Road, Qingdao, 266000, China
| | - Yanyan Yang
- Department of Immunology, School of Basic Medicine, Qingdao University, Qingdao, 266071, China
| | - Bei Zhang
- Department of Immunology, School of Basic Medicine, Qingdao University, Qingdao, 266071, China
| | - Xiaotong Lin
- Department of Respiratory Medicine, Qingdao Municipal Hospital, Qingdao, 266011, China
| | - Xiuxiu Fu
- Department of Cardiac Ultrasound, The Affiliated Hospital of Qingdao University, No. 16 Jiangsu Road, Qingdao, 266000, China
| | - Yi An
- Department of Cardiology, The Affiliated Hospital of Qingdao University, No. 1677 Wutaishan Road, Qingdao, 266555, China
| | - Yulin Zou
- Department of Cardiac Ultrasound, The Affiliated Hospital of Qingdao University, No. 16 Jiangsu Road, Qingdao, 266000, China
| | - Jian-Xun Wang
- Department of Immunology, School of Basic Medicine, Qingdao University, Qingdao, 266071, China
| | - Zhibin Wang
- Department of Cardiac Ultrasound, The Affiliated Hospital of Qingdao University, No. 16 Jiangsu Road, Qingdao, 266000, China.
| | - Tao Yu
- Center for Regenerative Medicine, Institute for Translational Medicine, The Affiliated Hospital of Qingdao University; Department of Cardiac Ultrasound, The Affiliated Hospital of Qingdao University, No. 16 Jiangsu Road, Qingdao, 266000, China.
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5
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Brooks GA, Osmond AD, Leija RG, Curl CC, Arevalo JA, Duong JJ, Horning MA. The blood lactate/pyruvate equilibrium affair. Am J Physiol Endocrinol Metab 2022; 322:E34-E43. [PMID: 34719944 PMCID: PMC8722269 DOI: 10.1152/ajpendo.00270.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The Lactate Shuttle hypothesis is supported by a variety of techniques including mass spectrometry analytics following infusion of carbon-labeled isotopic tracers. However, there has been controversy over whether lactate tracers measure lactate (L) or pyruvate (P) turnover. Here, we review the analytical errors, use of inappropriate tissue and animal models, failure to consider L and P pool sizes in modeling results, inappropriate tracer and blood sampling sites, and failure to anticipate roles of heart and lung parenchyma on L⇔P interactions. With support from magnetic resonance spectroscopy (MRS) and immunocytochemistry, we conclude that carbon-labeled lactate tracers can be used to quantitate lactate fluxes.
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Affiliation(s)
- George A Brooks
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Adam D Osmond
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Robert G Leija
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Casey C Curl
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Jose A Arevalo
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Justin J Duong
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Michael A Horning
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
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6
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Passarella S, Schurr A, Portincasa P. Mitochondrial Transport in Glycolysis and Gluconeogenesis: Achievements and Perspectives. Int J Mol Sci 2021; 22:ijms222312620. [PMID: 34884425 PMCID: PMC8657705 DOI: 10.3390/ijms222312620] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/16/2021] [Accepted: 11/19/2021] [Indexed: 01/22/2023] Open
Abstract
Some metabolic pathways involve two different cell components, for instance, cytosol and mitochondria, with metabolites traffic occurring from cytosol to mitochondria and vice versa, as seen in both glycolysis and gluconeogenesis. However, the knowledge on the role of mitochondrial transport within these two glucose metabolic pathways remains poorly understood, due to controversial information available in published literature. In what follows, we discuss achievements, knowledge gaps, and perspectives on the role of mitochondrial transport in glycolysis and gluconeogenesis. We firstly describe the experimental approaches for quick and easy investigation of mitochondrial transport, with respect to cell metabolic diversity. In addition, we depict the mitochondrial shuttles by which NADH formed in glycolysis is oxidized, the mitochondrial transport of phosphoenolpyruvate in the light of the occurrence of the mitochondrial pyruvate kinase, and the mitochondrial transport and metabolism of L-lactate due to the L-lactate translocators and to the mitochondrial L-lactate dehydrogenase located in the inner mitochondrial compartment.
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Affiliation(s)
- Salvatore Passarella
- Department of Biomedical Sciences and Human Oncology, University of Bari “Aldo Moro”, 70124 Bari, Italy
- Correspondence: ; Tel.: +39-3293606374
| | - Avital Schurr
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Louisville, Louisville, KY 40202, USA;
| | - Piero Portincasa
- Clinica Medica “A. Murri”, Department of Biomedical Sciences and Human Oncology, University of Bari “Aldo Moro”, 70124 Bari, Italy;
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7
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Dong S, Qian L, Cheng Z, Chen C, Wang K, Hu S, Zhang X, Wu T. Lactate and Myocadiac Energy Metabolism. Front Physiol 2021; 12:715081. [PMID: 34483967 PMCID: PMC8415870 DOI: 10.3389/fphys.2021.715081] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 07/29/2021] [Indexed: 12/05/2022] Open
Abstract
The myocardium is capable of utilizing different energy substrates, which is referred to as “metabolic flexibility.” This process assures ATP production from fatty acids, glucose, lactate, amino acids, and ketones, in the face of varying metabolic contexts. In the normal physiological state, the oxidation of fatty acids contributes to approximately 60% of energy required, and the oxidation of other substrates provides the rest. The accumulation of lactate in ischemic and hypoxic tissues has traditionally be considered as a by-product, and of little utility. However, recent evidence suggests that lactate may represent an important fuel for the myocardium during exercise or myocadiac stress. This new paradigm drives increasing interest in understanding its role in cardiac metabolism under both physiological and pathological conditions. In recent years, blood lactate has been regarded as a signal of stress in cardiac disease, linking to prognosis in patients with myocardial ischemia or heart failure. In this review, we discuss the importance of lactate as an energy source and its relevance to the progression and management of heart diseases.
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Affiliation(s)
- Shuohui Dong
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Linhui Qian
- Department of Colorectal and Anal Surgery, Feicheng Hospital Affiliated to Shandong First Medical University, Feicheng, China
| | - Zhiqiang Cheng
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Chang Chen
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Kexin Wang
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Sanyuan Hu
- Department of General Surgery, The First Affiliated Hospital of Shandong First Medical University, Jinan, China
| | - Xiang Zhang
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Tongzhi Wu
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, SA, Australia.,Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, SA, Australia
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8
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Kolodziej F, O’Halloran KD. Re-Evaluating the Oxidative Phenotype: Can Endurance Exercise Save the Western World? Antioxidants (Basel) 2021; 10:609. [PMID: 33921022 PMCID: PMC8071436 DOI: 10.3390/antiox10040609] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/06/2021] [Accepted: 04/10/2021] [Indexed: 01/16/2023] Open
Abstract
Mitochondria are popularly called the "powerhouses" of the cell. They promote energy metabolism through the tricarboxylic acid (TCA) cycle and oxidative phosphorylation, which in contrast to cytosolic glycolysis are oxygen-dependent and significantly more substrate efficient. That is, mitochondrial metabolism provides substantially more cellular energy currency (ATP) per macronutrient metabolised. Enhancement of mitochondrial density and metabolism are associated with endurance training, which allows for the attainment of high relative VO2 max values. However, the sedentary lifestyle and diet currently predominant in the Western world lead to mitochondrial dysfunction. Underdeveloped mitochondrial metabolism leads to nutrient-induced reducing pressure caused by energy surplus, as reduced nicotinamide adenine dinucleotide (NADH)-mediated high electron flow at rest leads to "electron leak" and a chronic generation of superoxide radicals (O2-). Chronic overload of these reactive oxygen species (ROS) damages cell components such as DNA, cell membranes, and proteins. Counterintuitively, transiently generated ROS during exercise contributes to adaptive reduction-oxidation (REDOX) signalling through the process of cellular hormesis or "oxidative eustress" defined by Helmut Sies. However, the unaccustomed, chronic oxidative stress is central to the leading causes of mortality in the 21st century-metabolic syndrome and the associated cardiovascular comorbidities. The endurance exercise training that improves mitochondrial capacity and the protective antioxidant cellular system emerges as a universal intervention for mitochondrial dysfunction and resultant comorbidities. Furthermore, exercise might also be a solution to prevent ageing-related degenerative diseases, which are caused by impaired mitochondrial recycling. This review aims to break down the metabolic components of exercise and how they translate to athletic versus metabolically diseased phenotypes. We outline a reciprocal relationship between oxidative metabolism and inflammation, as well as hypoxia. We highlight the importance of oxidative stress for metabolic and antioxidant adaptation. We discuss the relevance of lactate as an indicator of critical exercise intensity, and inferring from its relationship with hypoxia, we suggest the most appropriate mode of exercise for the case of a lost oxidative identity in metabolically inflexible patients. Finally, we propose a reciprocal signalling model that establishes a healthy balance between the glycolytic/proliferative and oxidative/prolonged-ageing phenotypes. This model is malleable to adaptation with oxidative stress in exercise but is also susceptible to maladaptation associated with chronic oxidative stress in disease. Furthermore, mutations of components involved in the transcriptional regulatory mechanisms of mitochondrial metabolism may lead to the development of a cancerous phenotype, which progressively presents as one of the main causes of death, alongside the metabolic syndrome.
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Affiliation(s)
- Filip Kolodziej
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, T12 XF62 Cork, Ireland;
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9
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Glancy B, Kane DA, Kavazis AN, Goodwin ML, Willis WT, Gladden LB. Mitochondrial lactate metabolism: history and implications for exercise and disease. J Physiol 2021; 599:863-888. [PMID: 32358865 PMCID: PMC8439166 DOI: 10.1113/jp278930] [Citation(s) in RCA: 89] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 03/25/2020] [Indexed: 12/31/2022] Open
Abstract
Mitochondrial structures were probably observed microscopically in the 1840s, but the idea of oxidative phosphorylation (OXPHOS) within mitochondria did not appear until the 1930s. The foundation for research into energetics arose from Meyerhof's experiments on oxidation of lactate in isolated muscles recovering from electrical contractions in an O2 atmosphere. Today, we know that mitochondria are actually reticula and that the energy released from electron pairs being passed along the electron transport chain from NADH to O2 generates a membrane potential and pH gradient of protons that can enter the molecular machine of ATP synthase to resynthesize ATP. Lactate stands at the crossroads of glycolytic and oxidative energy metabolism. Based on reported research and our own modelling in silico, we contend that lactate is not directly oxidized in the mitochondrial matrix. Instead, the interim glycolytic products (pyruvate and NADH) are held in cytosolic equilibrium with the products of the lactate dehydrogenase (LDH) reaction and the intermediates of the malate-aspartate and glycerol 3-phosphate shuttles. This equilibrium supplies the glycolytic products to the mitochondrial matrix for OXPHOS. LDH in the mitochondrial matrix is not compatible with the cytoplasmic/matrix redox gradient; its presence would drain matrix reducing power and substantially dissipate the proton motive force. OXPHOS requires O2 as the final electron acceptor, but O2 supply is sufficient in most situations, including exercise and often acute illness. Recent studies suggest that atmospheric normoxia may constitute a cellular hyperoxia in mitochondrial disease. As research proceeds appropriate oxygenation levels should be carefully considered.
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Affiliation(s)
- Brian Glancy
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Daniel A. Kane
- Department of Human Kinetics, St. Francis Xavier University, NS B2G 2W5, Antigonish, Canada
| | | | - Matthew L. Goodwin
- Department of Orthopaedic Surgery, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Wayne T. Willis
- College of Medicine, Department of Medicine, University of Arizona, Tucson, AZ 85724-5099, USA
| | - L. Bruce Gladden
- School of Kinesiology, Auburn University, Auburn, AL 36849-5323, USA
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10
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Brooks GA. The tortuous path of lactate shuttle discovery: From cinders and boards to the lab and ICU. JOURNAL OF SPORT AND HEALTH SCIENCE 2020; 9:446-460. [PMID: 32444344 PMCID: PMC7498672 DOI: 10.1016/j.jshs.2020.02.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/04/2019] [Accepted: 12/16/2019] [Indexed: 05/11/2023]
Abstract
Once thought to be a waste product of oxygen limited (anaerobic) metabolism, lactate is now known to form continuously under fully oxygenated (aerobic) conditions. Lactate shuttling between producer (driver) and consumer cells fulfills at least 3 purposes; lactate is: (1) a major energy source, (2) the major gluconeogenic precursor, and (3) a signaling molecule. The Lactate Shuttle theory is applicable to diverse fields such as sports nutrition and hydration, resuscitation from acidosis and Dengue, treatment of traumatic brain injury, maintenance of glycemia, reduction of inflammation, cardiac support in heart failure and following a myocardial infarction, and to improve cognition. Yet, dysregulated lactate shuttling disrupts metabolic flexibility, and worse, supports oncogenesis. Lactate production in cancer (the Warburg effect) is involved in all main sequela for carcinogenesis: angiogenesis, immune escape, cell migration, metastasis, and self-sufficient metabolism. The history of the tortuous path of discovery in lactate metabolism and shuttling was discussed in the 2019 American College of Sports Medicine Joseph B. Wolffe Lecture in Orlando, FL.
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Affiliation(s)
- George A Brooks
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California Berkeley, CA 94720-3140, USA.
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11
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Baltazar F, Afonso J, Costa M, Granja S. Lactate Beyond a Waste Metabolite: Metabolic Affairs and Signaling in Malignancy. Front Oncol 2020; 10:231. [PMID: 32257942 PMCID: PMC7093491 DOI: 10.3389/fonc.2020.00231] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Accepted: 02/11/2020] [Indexed: 12/16/2022] Open
Abstract
To sustain their high proliferation rates, most cancer cells rely on glycolytic metabolism, with production of lactic acid. For many years, lactate was seen as a metabolic waste of glycolytic metabolism; however, recent evidence has revealed new roles of lactate in the tumor microenvironment, either as metabolic fuel or as a signaling molecule. Lactate plays a key role in the different models of metabolic crosstalk proposed in malignant tumors: among cancer cells displaying complementary metabolic phenotypes and between cancer cells and other tumor microenvironment associated cells, including endothelial cells, fibroblasts, and diverse immune cells. This cell metabolic symbiosis/slavery supports several cancer aggressiveness features, including increased angiogenesis, immunological escape, invasion, metastasis, and resistance to therapy. Lactate transport is mediated by the monocarboxylate transporter (MCT) family, while another large family of G protein-coupled receptors (GPCRs), not yet fully characterized in the cancer context, is involved in lactate/acidosis signaling. In this mini-review, we will focus on the role of lactate in the tumor microenvironment, from metabolic affairs to signaling, including the function of lactate in the cancer-cancer and cancer-stromal shuttles, as well as a signaling oncometabolite. We will also review the prognostic value of lactate metabolism and therapeutic approaches designed to target lactate production and transport.
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Affiliation(s)
- Fátima Baltazar
- School of Medicine, Life and Health Sciences Research Institute (ICVS), University of Minho, Braga, Portugal
- ICVS/3B's—PT Government Associate Laboratory, Guimarães, Portugal
| | - Julieta Afonso
- School of Medicine, Life and Health Sciences Research Institute (ICVS), University of Minho, Braga, Portugal
- ICVS/3B's—PT Government Associate Laboratory, Guimarães, Portugal
| | - Marta Costa
- School of Medicine, Life and Health Sciences Research Institute (ICVS), University of Minho, Braga, Portugal
- ICVS/3B's—PT Government Associate Laboratory, Guimarães, Portugal
| | - Sara Granja
- School of Medicine, Life and Health Sciences Research Institute (ICVS), University of Minho, Braga, Portugal
- ICVS/3B's—PT Government Associate Laboratory, Guimarães, Portugal
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12
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Brooks GA. Lactate as a fulcrum of metabolism. Redox Biol 2020; 35:101454. [PMID: 32113910 PMCID: PMC7284908 DOI: 10.1016/j.redox.2020.101454] [Citation(s) in RCA: 272] [Impact Index Per Article: 68.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 01/28/2020] [Accepted: 02/05/2020] [Indexed: 12/17/2022] Open
Abstract
Mistakenly thought to be the consequence of oxygen lack in contracting skeletal muscle we now know that the L-enantiomer of the lactate anion is formed under fully aerobic conditions and is utilized continuously in diverse cells, tissues, organs and at the whole-body level. By shuttling between producer (driver) and consumer (recipient) cells lactate fulfills at least three purposes: 1] a major energy source for mitochondrial respiration; 2] the major gluconeogenic precursor; and 3] a signaling molecule. Working by mass action, cell redox regulation, allosteric binding, and reprogramming of chromatin by lactylation of lysine residues on histones, lactate has major influences in energy substrate partitioning. The physiological range of tissue [lactate] is 0.5–20 mM and the cellular Lactate/Pyruvate ratio (L/P) can range from 10 to >500; these changes during exercise and other stress-strain responses dwarf other metabolic signals in magnitude and span. Hence, lactate dynamics have rapid and major short- and long-term effects on cell redox and other control systems. By inhibiting lipolysis in adipose via HCAR-1, and muscle mitochondrial fatty acid uptake via malonyl-CoA and CPT1, lactate controls energy substrate partitioning. Repeated lactate exposure from regular exercise results in major effects on the expression of regulatory enzymes of glycolysis and mitochondrial respiration. Lactate is the fulcrum of metabolic regulation in vivo.
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Affiliation(s)
- George A Brooks
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, CA, 94720-3140, USA.
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13
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Young A, Oldford C, Mailloux RJ. Lactate dehydrogenase supports lactate oxidation in mitochondria isolated from different mouse tissues. Redox Biol 2019; 28:101339. [PMID: 31610469 PMCID: PMC6812140 DOI: 10.1016/j.redox.2019.101339] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 10/03/2019] [Accepted: 10/04/2019] [Indexed: 11/26/2022] Open
Abstract
Research over the past seventy years has established that mitochondrial-l-lactate dehydrogenase (m-L-LDH) is vital for mitochondrial bioenergetics. However, in recent report, Fulghum et al. concluded that lactate is a poor fuel for mitochondrial respiration [1]. In the present study, we have followed up on these findings and conducted an independent investigation to determine if lactate can support mitochondrial bioenergetics. We demonstrate herein that lactate can fuel the bioenergetics of heart, muscle, and liver mitochondria. Lactate was just as effective as pyruvate at stimulating mitochondrial coupling efficiency. Inclusion of LDH (sodium oxamate or GSK 2837808A) and pyruvate dehydrogenase (PDH; CPI-613) inhibitors abolished respiration in mitochondria energized with lactate. Lactate also fueled mitochondrial ROS generation and was just as effective as pyruvate at stimulating H2O2 production. Additionally, lactate-induced ROS production was inhibited by both LDH and PDH inhibitors. Enzyme activity measurements conducted on permeabilized mitochondria revealed that LDH is localized in mitochondria. In aggregate, we can conclude that mitochondrial LDH fuels bioenergetics in several tissues by oxidizing lactate. Lactate can fuel mitochondrial respiration. Lactate serves as a substrate for H2O2 production. Mitochondria contain LDH.
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Affiliation(s)
- Adrian Young
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Catherine Oldford
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Ryan J Mailloux
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada; The School of Human Nutrition, Faculty of Agricultural and Environmental Sciences, McGill University, Ste.-Anne-de-Bellevue, Quebec, Canada.
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14
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Russ AE, Schifino AG, Leong CH. Effect of lactate supplementation on V̇O 2peak and onset of blood lactate accumulation: A double-blind, placebo-controlled trial. ACTA GYMNICA 2019. [DOI: 10.5507/ag.2019.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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15
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Fulghum KL, Rood BR, Shang VO, McNally LA, Riggs DW, Zheng YT, Hill BG. Mitochondria-associated lactate dehydrogenase is not a biologically significant contributor to bioenergetic function in murine striated muscle. Redox Biol 2019; 24:101177. [PMID: 30939431 PMCID: PMC6441728 DOI: 10.1016/j.redox.2019.101177] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 03/08/2019] [Accepted: 03/21/2019] [Indexed: 12/17/2022] Open
Abstract
Previous studies indicate that mitochondria-localized lactate dehydrogenase (mLDH) might be a significant contributor to metabolism. In the heart, the presence of mLDH could provide cardiac mitochondria with a higher capacity to generate reducing equivalents directly available for respiration, especially during exercise when circulating lactate levels are high. The purpose of this study was to test the hypothesis that mLDH contributes to striated muscle bioenergetic function. Mitochondria isolated from murine cardiac and skeletal muscle lacked an appreciable ability to respire on lactate in the absence or presence of exogenous NAD+. Although three weeks of treadmill running promoted physiologic cardiac growth, mitochondria isolated from the hearts of acutely exercised or exercise-adapted mice showed no further increase in lactate oxidation capacity. In all conditions tested, cardiac mitochondria respired at >20-fold higher levels with provision of pyruvate compared with lactate. Similarly, skeletal muscle mitochondria showed little capacity to respire on lactate. Protease protection assays of isolated cardiac mitochondria confirmed that LDH is not localized within the mitochondrion. We conclude that mLDH does not contribute to cardiac bioenergetics in mice.
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Affiliation(s)
- Kyle L Fulghum
- Diabetes and Obesity Center, Envirome Institute, Department of Medicine, University of Louisville, Louisville, KY, USA; Department of Physiology and Biophysics, University of Louisville, Louisville, KY, USA
| | - Benjamin R Rood
- Diabetes and Obesity Center, Envirome Institute, Department of Medicine, University of Louisville, Louisville, KY, USA
| | - Velma O Shang
- Diabetes and Obesity Center, Envirome Institute, Department of Medicine, University of Louisville, Louisville, KY, USA; Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY, USA
| | - Lindsey A McNally
- Diabetes and Obesity Center, Envirome Institute, Department of Medicine, University of Louisville, Louisville, KY, USA
| | - Daniel W Riggs
- Diabetes and Obesity Center, Envirome Institute, Department of Medicine, University of Louisville, Louisville, KY, USA; Department of Bioinformatics and Biostatistics, University of Louisville, Louisville, KY, USA
| | - Yu-Ting Zheng
- Diabetes and Obesity Center, Envirome Institute, Department of Medicine, University of Louisville, Louisville, KY, USA
| | - Bradford G Hill
- Diabetes and Obesity Center, Envirome Institute, Department of Medicine, University of Louisville, Louisville, KY, USA; Department of Physiology and Biophysics, University of Louisville, Louisville, KY, USA; Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY, USA.
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16
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Schurr A. Glycolysis Paradigm Shift Dictates a Reevaluation of Glucose and Oxygen Metabolic Rates of Activated Neural Tissue. Front Neurosci 2018; 12:700. [PMID: 30364172 PMCID: PMC6192285 DOI: 10.3389/fnins.2018.00700] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 09/18/2018] [Indexed: 01/31/2023] Open
Abstract
In 1988 two seminal studies were published, both instigating controversy. One concluded that “the energy needs of activated neural tissue are minimal, being fulfilled via the glycolytic pathway alone,” a conclusion based on the observation that neural activation increased glucose consumption, which was not accompanied by a corresponding increase in oxygen consumption (Fox et al., 1988). The second demonstrated that neural tissue function can be supported exclusively by lactate as the energy substrate (Schurr et al., 1988). While both studies continue to have their supporters and detractors, the present review attempts to clarify the issues responsible for the persistence of the controversies they have provoked and offer a possible rationalization. The concept that lactate rather than pyruvate, is the glycolytic end-product, both aerobically and anaerobically, and thus the real mitochondrial oxidative substrate, has gained a greater acceptance over the years. The idea of glycolysis as the sole ATP supplier for neural activation (glucose → lactate + 2ATP) continues to be controversial. Lactate oxidative utilization by activated neural tissue could explain the mismatch between glucose and oxygen consumption and resolve the existing disagreements among users of imaging methods to measure the metabolic rates of the two energy metabolic substrates. The postulate that the energy necessary for active neural tissue is supplied by glycolysis alone stems from the original aerobic glycolysis paradigm. Accordingly, glucose consumption is accompanied by oxygen consumption at 1–6 ratio. Since Fox et al. (1988) observed only a minimal if non-existent oxygen consumption compared to glucose consumption, their conclusion make sense. Nevertheless, considering (a) the shift in the paradigm of glycolysis (glucose → lactate; lactate + O2 + mitochondria → pyruvate → TCA cycle → CO2 + H2O + 17ATP); (b) that one mole of lactate oxidation requires only 50% of the amount of oxygen necessary for the oxidation of one mole of glucose; and (c) that lactate, as a mitochondrial substrate, is over eight times more efficient at ATP production than glucose as a glycolytic substrate, suggest that future studies of cerebral metabolic rates of activated neural tissue should include along with the measurements of CMRO2 and CMRglucose the measurement of CMRlactate.
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Affiliation(s)
- Avital Schurr
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Louisville, Louisville, KY, United States
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17
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Lund J, Aas V, Tingstad RH, Van Hees A, Nikolić N. Utilization of lactic acid in human myotubes and interplay with glucose and fatty acid metabolism. Sci Rep 2018; 8:9814. [PMID: 29959350 PMCID: PMC6026123 DOI: 10.1038/s41598-018-28249-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 06/11/2018] [Indexed: 01/05/2023] Open
Abstract
Once assumed only to be a waste product of anaerobe glycolytic activity, lactate is now recognized as an energy source in skeletal muscles. While lactate metabolism has been extensively studied in vivo, underlying cellular processes are poorly described. This study aimed to examine lactate metabolism in cultured human myotubes and to investigate effects of lactate exposure on metabolism of oleic acid and glucose. Lactic acid, fatty acid and glucose metabolism were studied in myotubes using [14C(U)]lactic acid, [14C]oleic acid and [14C(U)]glucose, respectively. Myotubes expressed both the MCT1, MCT2, MCT3 and MCT4 lactate transporters, and lactic acid was found to be a substrate for both glycogen synthesis and lipid storage. Pyruvate and palmitic acid inhibited lactic acid oxidation, whilst glucose and α-cyano-4-hydroxycinnamic acid inhibited lactic acid uptake. Acute addition of lactic acid inhibited glucose and oleic acid oxidation, whereas oleic acid uptake was increased. Pretreatment with lactic acid for 24 h did not affect glucose or oleic acid metabolism. By replacing glucose with lactic acid during the whole culturing period, glucose uptake and oxidation were increased by 2.8-fold and 3-fold, respectively, and oleic acid oxidation was increased 1.4-fold. Thus, lactic acid has an important role in energy metabolism of human myotubes.
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Affiliation(s)
- Jenny Lund
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Vigdis Aas
- Department of Life Sciences and Health, Faculty of Health Sciences, OsloMet - Oslo Metropolitan University, Oslo, Norway
| | - Ragna H Tingstad
- Department of Life Sciences and Health, Faculty of Health Sciences, OsloMet - Oslo Metropolitan University, Oslo, Norway
| | - Alfons Van Hees
- Department of Life Sciences and Health, Faculty of Health Sciences, OsloMet - Oslo Metropolitan University, Oslo, Norway
| | - Nataša Nikolić
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway.
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18
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The Science and Translation of Lactate Shuttle Theory. Cell Metab 2018; 27:757-785. [PMID: 29617642 DOI: 10.1016/j.cmet.2018.03.008] [Citation(s) in RCA: 618] [Impact Index Per Article: 103.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/06/2018] [Accepted: 03/16/2018] [Indexed: 02/07/2023]
Abstract
Once thought to be a waste product of anaerobic metabolism, lactate is now known to form continuously under aerobic conditions. Shuttling between producer and consumer cells fulfills at least three purposes for lactate: (1) a major energy source, (2) the major gluconeogenic precursor, and (3) a signaling molecule. "Lactate shuttle" (LS) concepts describe the roles of lactate in delivery of oxidative and gluconeogenic substrates as well as in cell signaling. In medicine, it has long been recognized that the elevation of blood lactate correlates with illness or injury severity. However, with lactate shuttle theory in mind, some clinicians are now appreciating lactatemia as a "strain" and not a "stress" biomarker. In fact, clinical studies are utilizing lactate to treat pro-inflammatory conditions and to deliver optimal fuel for working muscles in sports medicine. The above, as well as historic and recent studies of lactate metabolism and shuttling, are discussed in the following review.
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19
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England EM, Shi H, Matarneh SK, Oliver EM, Helm ET, Scheffler TL, Puolanne E, Gerrard DE. Chronic activation of AMP-activated protein kinase increases monocarboxylate transporter 2 and 4 expression in skeletal muscle. J Anim Sci 2018; 95:3552-3562. [PMID: 28805903 DOI: 10.2527/jas.2017.1457] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Acute activation of AMP-activated protein kinase (AMPK) increases monocarboxylate transporter (MCT) expression in skeletal muscle. However, the impact of chronic activation of AMPK on MCT expression in skeletal muscle is unknown. To investigate, MCT1, MCT2, and MCT4 mRNA expression and protein abundance were measured in the longissimus lumborum (glycolytic), masseter (oxidative), and heart from wild-type (control) and AMPK γ3 pigs. The AMPK γ3 gain in function mutation results in AMPK being constitutively active in glycolytic skeletal muscle and increases energy producing pathways. The MCT1 and MCT2 mRNA expression in muscle was lower ( < 0.05) from both wild-type and AMPK γ3 animals compared to other tissues. However, in both genotypes, MCT1 and MCT2 mRNA expression was greater ( < 0.05) in the masseter than the longissimus lumborum. The MCT1 protein was not detected in skeletal muscle, but MCT2 was greater ( < 0.05) in muscles with an oxidative muscle phenotype. Monocarboxylate transporter 2 was also detected in muscle mitochondria and may explain the differences between muscles. The MCT4 mRNA expression was intermediate among all tissues tested and greater ( < 0.05) in the longissimus lumborum than the masseter. Furthermore, MCT4 protein expression in the longissimus lumborum from AMPK γ3 animals was greater ( < 0.05) than in the longissimus lumborum from wild-type animals. In totality, these data indicate that chronic AMPK activation simultaneously increases MCT2 and MCT4 expression in skeletal muscle.
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20
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Ferguson BS, Rogatzki MJ, Goodwin ML, Kane DA, Rightmire Z, Gladden LB. Lactate metabolism: historical context, prior misinterpretations, and current understanding. Eur J Appl Physiol 2018; 118:691-728. [PMID: 29322250 DOI: 10.1007/s00421-017-3795-6] [Citation(s) in RCA: 202] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 12/22/2017] [Indexed: 02/07/2023]
Abstract
Lactate (La-) has long been at the center of controversy in research, clinical, and athletic settings. Since its discovery in 1780, La- has often been erroneously viewed as simply a hypoxic waste product with multiple deleterious effects. Not until the 1980s, with the introduction of the cell-to-cell lactate shuttle did a paradigm shift in our understanding of the role of La- in metabolism begin. The evidence for La- as a major player in the coordination of whole-body metabolism has since grown rapidly. La- is a readily combusted fuel that is shuttled throughout the body, and it is a potent signal for angiogenesis irrespective of oxygen tension. Despite this, many fundamental discoveries about La- are still working their way into mainstream research, clinical care, and practice. The purpose of this review is to synthesize current understanding of La- metabolism via an appraisal of its robust experimental history, particularly in exercise physiology. That La- production increases during dysoxia is beyond debate, but this condition is the exception rather than the rule. Fluctuations in blood [La-] in health and disease are not typically due to low oxygen tension, a principle first demonstrated with exercise and now understood to varying degrees across disciplines. From its role in coordinating whole-body metabolism as a fuel to its role as a signaling molecule in tumors, the study of La- metabolism continues to expand and holds potential for multiple clinical applications. This review highlights La-'s central role in metabolism and amplifies our understanding of past research.
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Affiliation(s)
- Brian S Ferguson
- College of Applied Health Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Matthew J Rogatzki
- Department of Health and Exercise Science, Appalachian State University, Boone, NC, USA
| | - Matthew L Goodwin
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA.,Huntsman Cancer Institute, Salt Lake City, UT, USA
| | - Daniel A Kane
- Department of Human Kinetics, St. Francis Xavier University, Antigonish, Canada
| | - Zachary Rightmire
- School of Kinesiology, Auburn University, 301 Wire Road, Auburn, AL, 36849, USA
| | - L Bruce Gladden
- School of Kinesiology, Auburn University, 301 Wire Road, Auburn, AL, 36849, USA.
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21
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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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22
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Mason S. Lactate Shuttles in Neuroenergetics-Homeostasis, Allostasis and Beyond. Front Neurosci 2017; 11:43. [PMID: 28210209 PMCID: PMC5288365 DOI: 10.3389/fnins.2017.00043] [Citation(s) in RCA: 134] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 01/20/2017] [Indexed: 12/19/2022] Open
Abstract
Understanding brain energy metabolism—neuroenergetics—is becoming increasingly important as it can be identified repeatedly as the source of neurological perturbations. Within the scientific community we are seeing a shift in paradigms from the traditional neurocentric view to that of a more dynamic, integrated one where astrocytes are no longer considered as being just supportive, and activated microglia have a profound influence. Lactate is emerging as the “good guy,” contrasting its classical “bad guy” position in the now superseded medical literature. This review begins with the evolution of the concept of “lactate shuttles”; goes on to the recent shift in ideas regarding normal neuroenergetics (homeostasis)—specifically, the astrocyte–neuron lactate shuttle; and progresses to covering the metabolic implications whereby homeostasis is lost—a state of allostasis, and the function of microglia. The role of lactate, as a substrate and shuttle, is reviewed in light of allostatic stress, and beyond—in an acute state of allostatic stress in terms of physical brain trauma, and reflected upon with respect to persistent stress as allostatic overload—neurodegenerative diseases. Finally, the recently proposed astrocyte–microglia lactate shuttle is discussed in terms of chronic neuroinflammatory infectious diseases, using tuberculous meningitis as an example. The novelty extended by this review is that the directionality of lactate, as shuttles in the brain, in neuropathophysiological states is emerging as crucial in neuroenergetics.
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Affiliation(s)
- Shayne Mason
- Centre for Human Metabolomics, North-West University Potchefstroom, South Africa
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23
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Jha MK, Lee IK, Suk K. Metabolic reprogramming by the pyruvate dehydrogenase kinase-lactic acid axis: Linking metabolism and diverse neuropathophysiologies. Neurosci Biobehav Rev 2016; 68:1-19. [PMID: 27179453 DOI: 10.1016/j.neubiorev.2016.05.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/11/2016] [Accepted: 05/09/2016] [Indexed: 12/12/2022]
Abstract
Emerging evidence indicates that there is a complex interplay between metabolism and chronic disorders in the nervous system. In particular, the pyruvate dehydrogenase (PDH) kinase (PDK)-lactic acid axis is a critical link that connects metabolic reprogramming and the pathophysiology of neurological disorders. PDKs, via regulation of PDH complex activity, orchestrate the conversion of pyruvate either aerobically to acetyl-CoA, or anaerobically to lactate. The kinases are also involved in neurometabolic dysregulation under pathological conditions. Lactate, an energy substrate for neurons, is also a recently acknowledged signaling molecule involved in neuronal plasticity, neuron-glia interactions, neuroimmune communication, and nociception. More recently, the PDK-lactic acid axis has been recognized to modulate neuronal and glial phenotypes and activities, contributing to the pathophysiologies of diverse neurological disorders. This review covers the recent advances that implicate the PDK-lactic acid axis as a novel linker of metabolism and diverse neuropathophysiologies. We finally explore the possibilities of employing the PDK-lactic acid axis and its downstream mediators as putative future therapeutic strategies aimed at prevention or treatment of neurological disorders.
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Affiliation(s)
- Mithilesh Kumar Jha
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 PLUS KNU Biomedical Convergence Program, Kyungpook National University School of Medicine, Daegu, Republic of Korea; Department of Neurology, Division of Neuromuscular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - In-Kyu Lee
- Department of Internal Medicine, Division of Endocrinology and Metabolism, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Kyoungho Suk
- Department of Pharmacology, Brain Science and Engineering Institute, BK21 PLUS KNU Biomedical Convergence Program, Kyungpook National University School of Medicine, Daegu, Republic of Korea.
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24
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Bonen A, Hatta H, Holloway GP, Spriet LL, Yoshida Y. Reply from Arend Bonen, Hideo Hatta, Graham P. Holloway, Lawrence L. Spriet and Yuko Yoshida. J Physiol 2015; 584:707-8. [PMID: 26659545 DOI: 10.1113/jphysiol.2007.143008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Arend Bonen
- Department of Human Health and Nutritional Sciences, University of Guelph Guelph Ontario N1G 2W1, Canada Department of Life Sciences, College of Arts and Sciences, University of Tokyo Komaba 3-8-1, Meguro-ku, Tokyo 1538902, Japan
| | - Hideo Hatta
- Department of Human Health and Nutritional Sciences, University of Guelph Guelph Ontario N1G 2W1, Canada Department of Life Sciences, College of Arts and Sciences, University of Tokyo Komaba 3-8-1, Meguro-ku, Tokyo 1538902, Japan
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph Guelph Ontario N1G 2W1, Canada Department of Life Sciences, College of Arts and Sciences, University of Tokyo Komaba 3-8-1, Meguro-ku, Tokyo 1538902, Japan
| | - Lawrence L Spriet
- Department of Human Health and Nutritional Sciences, University of Guelph Guelph Ontario N1G 2W1, Canada Department of Life Sciences, College of Arts and Sciences, University of Tokyo Komaba 3-8-1, Meguro-ku, Tokyo 1538902, Japan
| | - Yuko Yoshida
- Department of Human Health and Nutritional Sciences, University of Guelph Guelph Ontario N1G 2W1, Canada Department of Life Sciences, College of Arts and Sciences, University of Tokyo Komaba 3-8-1, Meguro-ku, Tokyo 1538902, Japan
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25
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Park JM, Josan S, Mayer D, Hurd RE, Chung Y, Bendahan D, Spielman DM, Jue T. Hyperpolarized 13C NMR observation of lactate kinetics in skeletal muscle. ACTA ACUST UNITED AC 2015; 218:3308-18. [PMID: 26347554 DOI: 10.1242/jeb.123141] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 08/21/2015] [Indexed: 01/02/2023]
Abstract
The production of glycolytic end products, such as lactate, usually evokes a cellular shift from aerobic to anaerobic ATP generation and O2 insufficiency. In the classical view, muscle lactate must be exported to the liver for clearance. However, lactate also forms under well-oxygenated conditions, and this has led investigators to postulate lactate shuttling from non-oxidative to oxidative muscle fiber, where it can serve as a precursor. Indeed, the intracellular lactate shuttle and the glycogen shunt hypotheses expand the vision to include a dynamic mobilization and utilization of lactate during a muscle contraction cycle. Testing the tenability of these provocative ideas during a rapid contraction cycle has posed a technical challenge. The present study reports the use of hyperpolarized [1-(13)C]lactate and [2-(13)C]pyruvate in dynamic nuclear polarization (DNP) NMR experiments to measure the rapid pyruvate and lactate kinetics in rat muscle. With a 3 s temporal resolution, (13)C DNP NMR detects both [1-(13)C]lactate and [2-(13)C]pyruvate kinetics in muscle. Infusion of dichloroacetate stimulates pyruvate dehydrogenase activity and shifts the kinetics toward oxidative metabolism. Bicarbonate formation from [1-(13)C]lactate increases sharply and acetyl-l-carnitine, acetoacetate and glutamate levels also rise. Such a quick mobilization of pyruvate and lactate toward oxidative metabolism supports the postulated role of lactate in the glycogen shunt and the intracellular lactate shuttle models. The study thus introduces an innovative DNP approach to measure metabolite transients, which will help delineate the cellular and physiological role of lactate and glycolytic end products.
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Affiliation(s)
- Jae Mo Park
- Radiology, Stanford University, Stanford, CA 94305, USA
| | - Sonal Josan
- Radiology, Stanford University, Stanford, CA 94305, USA Neuroscience Program, SRI International, Menlo Park, CA 94025, USA
| | - Dirk Mayer
- Neuroscience Program, SRI International, Menlo Park, CA 94025, USA Diagnostic Radiology and Nuclear Medicine, University of Maryland, Baltimore, MD 21201, USA
| | | | - Youngran Chung
- Biochemistry and Molecular Medicine, University of California Davis, Davis, CA 95616, USA
| | - David Bendahan
- Centre de Resonance Magnetique Biologique et Medicale, Aix-Marseille University, Marseille 13385, France
| | | | - Thomas Jue
- Biochemistry and Molecular Medicine, University of California Davis, Davis, CA 95616, USA
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26
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Passarella S, Paventi G, Pizzuto R. The mitochondrial L-lactate dehydrogenase affair. Front Neurosci 2014; 8:407. [PMID: 25538557 PMCID: PMC4260494 DOI: 10.3389/fnins.2014.00407] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Accepted: 11/22/2014] [Indexed: 11/24/2022] Open
Affiliation(s)
- Salvatore Passarella
- Department of Medicine and Health Sciences, University of Molise Campobasso, Italy
| | - Gianluca Paventi
- Department of Medicine and Health Sciences, University of Molise Campobasso, Italy
| | - Roberto Pizzuto
- Department of Medicine and Health Sciences, University of Molise Campobasso, Italy
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27
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Schurr A. Cerebral glycolysis: a century of persistent misunderstanding and misconception. Front Neurosci 2014; 8:360. [PMID: 25477776 PMCID: PMC4237041 DOI: 10.3389/fnins.2014.00360] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 10/21/2014] [Indexed: 11/18/2022] Open
Abstract
Since its discovery in 1780, lactate (lactic acid) has been blamed for almost any illness outcome in which its levels are elevated. Beginning in the mid-1980s, studies on both muscle and brain tissues, have suggested that lactate plays a role in bioenergetics. However, great skepticism and, at times, outright antagonism has been exhibited by many to any perceived role for this monocarboxylate in energy metabolism. The present review attempts to trace the negative attitudes about lactate to the first four or five decades of research on carbohydrate metabolism and its dogma according to which lactate is a useless anaerobic end-product of glycolysis. The main thrust here is the review of dozens of scientific publications, many by the leading scientists of their times, through the first half of the twentieth century. Consequently, it is concluded that there exists a barrier, described by Howard Margolis as “habit of mind,” that many scientists find impossible to cross. The term suggests “entrenched responses that ordinarily occur without conscious attention and that, even if noticed, are hard to change.” Habit of mind has undoubtedly played a major role in the above mentioned negative attitudes toward lactate. As early as the 1920s, scientists investigating brain carbohydrate metabolism had discovered that lactate can be oxidized by brain tissue preparations, yet their own habit of mind redirected them to believe that such an oxidation is simply a disposal mechanism of this “poisonous” compound. The last section of the review invites the reader to consider a postulated alternative glycolytic pathway in cerebral and, possibly, in most other tissues, where no distinction is being made between aerobic and anaerobic glycolysis; lactate is always the glycolytic end product. Aerobically, lactate is readily shuttled and transported into the mitochondrion, where it is converted to pyruvate via a mitochondrial lactate dehydrogenase (mLDH) and then is entered the tricarboxylic acid (TCA) cycle.
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Affiliation(s)
- Avital Schurr
- Department of Anesthesiology and Perioperative Medicine, University of Louisville School of Medicine Louisville, KY, USA
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28
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29
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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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Reevaluating Metabolism in Alzheimer's Disease from the Perspective of the Astrocyte-Neuron Lactate Shuttle Model. JOURNAL OF NEURODEGENERATIVE DISEASES 2013; 2013:234572. [PMID: 26316984 PMCID: PMC4437330 DOI: 10.1155/2013/234572] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 04/02/2013] [Indexed: 01/19/2023]
Abstract
The conventional view of central nervous system (CNS) metabolism is based on the assumption that glucose is the main fuel source for active neurons and is processed in an oxidative manner. However, since the early 1990s research has challenged the idea that the energy needs of nerve cells are met exclusively by glucose and oxidative metabolism. This alternative view of glucose utilization contends that astrocytes metabolize glucose to lactate, which is then released and taken up by nearby neurons and used as a fuel source, commonly known as the astrocyte-neuron lactate shuttle (ANLS) model. Once thought of as a waste metabolite, lactate has emerged as a central player in the maintenance of neuronal function and long-term memory. Decreased neuronal metabolism has traditionally been viewed as a hallmark feature of Alzheimer's disease (AD). However, a more complex picture of CNS metabolism is emerging that may provide valuable insight into the pathophysiological changes that occur during AD and other neurodegenerative diseases. This review will examine the ANLS model and present recent evidence highlighting the critical role that lactate plays in neuronal survival and memory. Moreover, the role of glucose and lactate metabolism in AD will be re-evaluated from the perspective of the ANLS.
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31
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Jacobs RA, Meinild AK, Nordsborg NB, Lundby C. Lactate oxidation in human skeletal muscle mitochondria. Am J Physiol Endocrinol Metab 2013; 304:E686-94. [PMID: 23384769 DOI: 10.1152/ajpendo.00476.2012] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Lactate is an important intermediate metabolite in human bioenergetics and is oxidized in many different tissues including the heart, brain, kidney, adipose tissue, liver, and skeletal muscle. The mechanism(s) explaining the metabolism of lactate in these tissues, however, remains unclear. Here, we analyze the ability of skeletal muscle to respire lactate by using an in situ mitochondrial preparation that leaves the native tubular reticulum and subcellular interactions of the organelle unaltered. Skeletal muscle biopsies were obtained from vastus lateralis muscle in 16 human subjects. Samples were chemically permeabilized with saponin, which selectively perforates the sarcolemma and facilitates the loss of cytosolic content without altering mitochondrial membranes, structure, and subcellular interactions. High-resolution respirometry was performed on permeabilized muscle biopsy preparations. By use of four separate and specific substrate titration protocols, the respirometric analysis revealed that mitochondria were capable of oxidizing lactate in the absence of exogenous LDH. The titration of lactate and NAD(+) into the respiration medium stimulated respiration (P ≤ 0.003). The addition of exogenous LDH failed to increase lactate-stimulated respiration (P = 1.0). The results further demonstrate that human skeletal muscle mitochondria cannot directly oxidize lactate within the mitochondrial matrix. Alternately, these data support previous claims that lactate is converted to pyruvate within the mitochondrial intermembrane space with the pyruvate subsequently taken into the mitochondrial matrix where it enters the TCA cycle and is ultimately oxidized.
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Affiliation(s)
- Robert A Jacobs
- Zurich Center for Integrative Human Physiology, Zurich, Switzerland.
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32
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White AT, Schenk S. NAD(+)/NADH and skeletal muscle mitochondrial adaptations to exercise. Am J Physiol Endocrinol Metab 2012; 303:E308-21. [PMID: 22436696 PMCID: PMC3423123 DOI: 10.1152/ajpendo.00054.2012] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 03/15/2012] [Indexed: 12/21/2022]
Abstract
The pyridine nucleotides, NAD(+) and NADH, are coenzymes that provide oxidoreductive power for the generation of ATP by mitochondria. In skeletal muscle, exercise perturbs the levels of NAD(+), NADH, and consequently, the NAD(+)/NADH ratio, and initial research in this area focused on the contribution of redox control to ATP production. More recently, numerous signaling pathways that are sensitive to perturbations in NAD(+)(H) have come to the fore, as has an appreciation for the potential importance of compartmentation of NAD(+)(H) metabolism and its subsequent effects on various signaling pathways. These pathways, which include the sirtuin (SIRT) proteins SIRT1 and SIRT3, the poly(ADP-ribose) polymerase (PARP) proteins PARP1 and PARP2, and COOH-terminal binding protein (CtBP), are of particular interest because they potentially link changes in cellular redox state to both immediate, metabolic-related changes and transcriptional adaptations to exercise. In this review, we discuss what is known, and not known, about the contribution of NAD(+)(H) metabolism and these aforementioned proteins to mitochondrial adaptations to acute and chronic endurance exercise.
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Affiliation(s)
- Amanda T White
- Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA
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33
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White AT, Schenk S. NAD(+)/NADH and skeletal muscle mitochondrial adaptations to exercise. AMERICAN JOURNAL OF PHYSIOLOGY. ENDOCRINOLOGY AND METABOLISM 2012. [PMID: 22436696 DOI: 10.1152/ajpendo.00054.2012.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The pyridine nucleotides, NAD(+) and NADH, are coenzymes that provide oxidoreductive power for the generation of ATP by mitochondria. In skeletal muscle, exercise perturbs the levels of NAD(+), NADH, and consequently, the NAD(+)/NADH ratio, and initial research in this area focused on the contribution of redox control to ATP production. More recently, numerous signaling pathways that are sensitive to perturbations in NAD(+)(H) have come to the fore, as has an appreciation for the potential importance of compartmentation of NAD(+)(H) metabolism and its subsequent effects on various signaling pathways. These pathways, which include the sirtuin (SIRT) proteins SIRT1 and SIRT3, the poly(ADP-ribose) polymerase (PARP) proteins PARP1 and PARP2, and COOH-terminal binding protein (CtBP), are of particular interest because they potentially link changes in cellular redox state to both immediate, metabolic-related changes and transcriptional adaptations to exercise. In this review, we discuss what is known, and not known, about the contribution of NAD(+)(H) metabolism and these aforementioned proteins to mitochondrial adaptations to acute and chronic endurance exercise.
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Affiliation(s)
- Amanda T White
- Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA
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34
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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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35
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Peveler WW, Palmer TG. Effect of Magnesium Lactate Dihydrate and Calcium Lactate Monohydrate on 20-km Cycling Time Trial Performance. J Strength Cond Res 2012; 26:1149-53. [PMID: 22398820 DOI: 10.1519/jsc.0b013e31822dcd7f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Willard W Peveler
- Department of Kinesiology and Health, Northern Kentucky University, Highland Heights, Kentucky, USA.
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36
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Halestrap AP, Wilson MC. The monocarboxylate transporter family--role and regulation. IUBMB Life 2011; 64:109-19. [PMID: 22162139 DOI: 10.1002/iub.572] [Citation(s) in RCA: 498] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 08/08/2011] [Indexed: 11/07/2022]
Abstract
Monocarboxylate transporter (MCT) isoforms 1-4 catalyze the proton-linked transport of monocarboxylates such as L-lactate across the plasma membrane, whereas MCT8 and MCT10 are thyroid hormone and aromatic amino acid transporters, respectively. The importance of MCTs is becoming increasingly evident as their extensive physiological and pathological roles are revealed. MCTs 1-4 play essential metabolic roles in most tissues with their distinct properties, expression profile, and subcellular localization matching the particular metabolic needs of a tissue. Important metabolic roles include energy metabolism in the brain, skeletal muscle, heart, tumor cells, and T-lymphocyte activation, gluconeogenesis in the liver and kidney, spermatogenesis, bowel metabolism of short-chain fatty acids, and drug transport. MCT8 is essential for thyroid hormone transport across the blood-brain barrier. Genetic perturbation of MCT function may be involved in disease states such as pancreatic β-cell malfunction (inappropriate MCT1 expression), chronic fatigue syndromes (impairment of muscle MCT function), and psychomotor retardation (MCT8 mutation). MCT expression can be regulated at both the transcriptional and post-transcriptional levels. Of particular importance is the upregulation of muscle MCT1 expression in response to training and MCT4 expression in response to hypoxia. The latter is mediated by hypoxia inducible factor 1α and often observed in tumor cells that rely almost entirely on glycolysis for their energy provision. The recent discovery of potent and specific MCT1 inhibitors that prevent proliferation of T-lymphocytes confirms that MCTs may be promising pharmacological targets including for cancer chemotherapy.
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Affiliation(s)
- Andrew P Halestrap
- School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol, UK.
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37
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Abstract
Mammalian skeletal muscle comprises different fiber types, whose identity is first established during embryonic development by intrinsic myogenic control mechanisms and is later modulated by neural and hormonal factors. The relative proportion of the different fiber types varies strikingly between species, and in humans shows significant variability between individuals. Myosin heavy chain isoforms, whose complete inventory and expression pattern are now available, provide a useful marker for fiber types, both for the four major forms present in trunk and limb muscles and the minor forms present in head and neck muscles. However, muscle fiber diversity involves all functional muscle cell compartments, including membrane excitation, excitation-contraction coupling, contractile machinery, cytoskeleton scaffold, and energy supply systems. Variations within each compartment are limited by the need of matching fiber type properties between different compartments. Nerve activity is a major control mechanism of the fiber type profile, and multiple signaling pathways are implicated in activity-dependent changes of muscle fibers. The characterization of these pathways is raising increasing interest in clinical medicine, given the potentially beneficial effects of muscle fiber type switching in the prevention and treatment of metabolic diseases.
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Affiliation(s)
- Stefano Schiaffino
- Venetian Institute of Molecular Medicine, Department of Biomedical Sciences, University of Padova, Consiglio Nazionale delle Ricerche Institute of Neurosciences, and Department of Human Anatomy and Physiology, University of Padova, Padova, Italy
| | - Carlo Reggiani
- Venetian Institute of Molecular Medicine, Department of Biomedical Sciences, University of Padova, Consiglio Nazionale delle Ricerche Institute of Neurosciences, and Department of Human Anatomy and Physiology, University of Padova, Padova, Italy
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38
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Świderek K, Paneth P. Binding ligands and cofactor to L-lactate dehydrogenase from human skeletal and heart muscles. J Phys Chem B 2011; 115:6366-76. [PMID: 21526780 DOI: 10.1021/jp201626k] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Binding affinities of cofactor and ligands to the active site of two different isoforms of lactate dehydrogenase (LDH), heart and skeletal muscles (H4 and M4, respectively), can be used for medical and biological applications. Herein, a hybrid QM/MM computational approach based on free energy perturbation methods has been carried out to estimate binding affinities and binding isotope effects (BIEs) for NADH/NAD(+) and oxamate, pyruvate, L-lactate, and D-lactate ligands to the M4 and H4 isoforms of L-LDH. Here, we show that determining how cofactor and ligands interact with the active site of LDH isoforms advanced the still open discussion on the intracellular lactate shuttle hypothesis. In our discussion we deny the key concept of this hypothesis showing, based on interaction energy values, that there is no evidence that the M4 type of LDH in the skeletal muscles cells served as a catalyst of the conversion of lactate to pyruvate. Additionally, theoretical determination of BIEs for H4 and M4 types of LDH shows that there is a way of using the BIEs as a tool capable to distinguish these isoforms, and for this purpose D-lactate labeled with deuterium in positions 11 or 7, 8, 9 ([11-2H]-BIE and [7,8,9-2H3]-BIE) or L-lactate labeled only in position 11 ([11-2H]-BIE) could be used. We propose the BIEs as a useful tool which can be applied in order to experimentally determine the types of LDH.
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Affiliation(s)
- Katarzyna Świderek
- Institute of Applied Radiation Chemistry, Technical University of Lodz, Zeromskiego 116, 90-924 Lodz, Poland.
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39
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Giulivi C, Ross-Inta C, Omanska-Klusek A, Napoli E, Sakaguchi D, Barrientos G, Allen PD, Pessah IN. Basal bioenergetic abnormalities in skeletal muscle from ryanodine receptor malignant hyperthermia-susceptible R163C knock-in mice. J Biol Chem 2011; 286:99-113. [PMID: 20978128 PMCID: PMC3013050 DOI: 10.1074/jbc.m110.153247] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Revised: 10/13/2010] [Indexed: 12/25/2022] Open
Abstract
Malignant hyperthermia (MH) and central core disease in humans have been associated with mutations in the skeletal ryanodine receptor (RyR1). Heterozygous mice expressing the human MH/central core disease RyR1 R163C mutation exhibit MH when exposed to halothane or heat stress. Considering that many MH symptoms resemble those that could ensue from a mitochondrial dysfunction (e.g. metabolic acidosis and hyperthermia) and that MH-susceptible mice or humans have a higher than normal cytoplasmic Ca(2+) concentration at rest, we evaluated the role of mitochondria in skeletal muscle from R163C compared with wild type mice under basal (untriggered) conditions. R163C skeletal muscle exhibited a significant increase in matrix Ca(2+), increased reactive oxygen species production, lower expression of mitochondrial proteins, and higher mtDNA copy number. These changes, in conjunction with lower myoglobin and glycogen contents, Myh4 and GAPDH transcript levels, GAPDH activity, and lower glucose utilization suggested a switch to a compromised bioenergetic state characterized by both low oxidative phosphorylation and glycolysis. The shift in bioenergetic state was accompanied by a dysregulation of Ca(2+)-responsive signaling pathways regulated by calcineurin and ERK1/2. Chronically elevated resting Ca(2+) in R163C skeletal muscle elicited the maintenance of a fast-twitch fiber program and the development of insulin resistance-like phenotype as part of a metabolic adaptation to the R163C RyR1 mutation.
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Affiliation(s)
- Cecilia Giulivi
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California 95616, USA.
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40
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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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41
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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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Benton CR, Yoshida Y, Lally J, Han XX, Hatta H, Bonen A. PGC-1alpha increases skeletal muscle lactate uptake by increasing the expression of MCT1 but not MCT2 or MCT4. Physiol Genomics 2008; 35:45-54. [PMID: 18523157 DOI: 10.1152/physiolgenomics.90217.2008] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined the relationship between PGC-1alpha protein; the monocarboxylate transporters MCT1, 2, and 4; and CD147 1) among six metabolically heterogeneous rat muscles, 2) in chronically stimulated red (RTA) and white tibialis (WTA) muscles (7 days), and 3) in RTA and WTA muscles transfected with PGC-1alpha-pcDNA plasmid in vivo. Among rat hindlimb muscles, there was a strong positive association between PGC-1alpha and MCT1 and CD147, and between MCT1 and CD147. A negative association was found between PGC-1alpha and MCT4, and CD147 and MCT4, while there was no relationship between PGC-1alpha or CD147 and MCT2. Transfecting PGC-1alpha-pcDNA plasmid into muscle increased PGC-1alpha protein (RTA +23%; WTA +25%) and induced the expression of MCT1 (RTA +16%; WTA +28%), but not MCT2 and MCT4. As a result of the PGC-1alpha-induced upregulation of MCT1 and its chaperone CD147 (+29%), there was a concomitant increase in the rate of lactate uptake (+20%). In chronically stimulated muscles, the following proteins were upregulated, PGC-1alpha in RTA (+26%) and WTA (+86%), MCT1 in RTA (+61%) and WTA (+180%), and CD147 in WTA (+106%). In contrast, MCT4 protein expression was not altered in either RTA or WTA muscles, while MCT2 protein expression was reduced in both RTA (-14%) and WTA (-10%). In these studies, whether comparing oxidative capacities among muscles or increasing their oxidative capacities by PGC-1alpha transfection and chronic muscle stimulation, there was a strong relationship between the expression of PGC-1alpha and MCT1, and PGC-1alpha and CD147 proteins. Thus, MCT1 and CD147 belong to the family of metabolic genes whose expression is regulated by PGC-1alpha in skeletal muscle.
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Affiliation(s)
- Carley R Benton
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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43
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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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44
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HASHIMOTO TAKESHI, BROOKS GEORGEA. Mitochondrial Lactate Oxidation Complex and an Adaptive Role for Lactate Production. Med Sci Sports Exerc 2008; 40:486-94. [PMID: 18379211 DOI: 10.1249/mss.0b013e31815fcb04] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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45
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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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46
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Kohn TA, Essén-Gustavsson B, Myburgh KH. Do skeletal muscle phenotypic characteristics of Xhosa and Caucasian endurance runners differ when matched for training and racing distances? J Appl Physiol (1985) 2007; 103:932-40. [PMID: 17585041 DOI: 10.1152/japplphysiol.01221.2006] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although East African black athletes dominate endurance running events, it is unknown whether black and white endurance runners with similar racing ability, matched for training, may differ in their skeletal muscle biochemical phenotype. Thirteen Xhosa (XR) and 13 Caucasian (CR) endurance runners were recruited and matched for 10-km performance, average preferred racing distance (PRDA), and training volume. Submaximal and maximal exercise tests were done, and vastus lateralis muscle biopsies were taken. XR were significantly lighter and shorter than CR athletes but had similar maximum oxygen consumption corrected for body weight and peak treadmill speed (PTS). XR had lower plasma lactate concentrations at 80% PTS ( P < 0.05) compared with CR. Also, XR had more type IIA (42.4 ± 9.2 vs. 31.3 ± 11.5%, P < 0.05) and less type I fibers (47.8 ± 10.9 vs. 63.1 ± 13.2%, P < 0.05), although oxidative enzyme activities did not differ. Furthermore, XR compared with CR had higher lactate dehydrogenase (LDH) activity in homogenate muscle samples (383 ± 99 vs. 229 ± 85 μmol·min−1·g dry weight−1, P < 0.05) and in both type IIa ( P < 0.05) and type I ( P = 0.05) single-fiber pools. A marked difference ( P < 0.05) in the composition of LDH isoform content was found between the two groups with XR having higher levels of LDH5-4 isoforms (skeletal muscle isozymes; LDH-M) than CR, which was not accounted for by fiber-type differences alone. These results confirm differences in muscle phenotype and physiological characteristics, particularly associated with high-intensity running.
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Affiliation(s)
- Tertius A Kohn
- Department of Physiological Sciences, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa
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47
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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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Philp A, Macdonald AL, Watt PW. Lactate--a signal coordinating cell and systemic function. ACTA ACUST UNITED AC 2006; 208:4561-75. [PMID: 16326938 DOI: 10.1242/jeb.01961] [Citation(s) in RCA: 211] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Since its first documented observation in exhausted animal muscle in the early 19th century, the role of lactate (lactic acid) has fascinated muscle physiologists and biochemists. Initial interpretation was that lactate appeared as a waste product and was responsible in some way for exhaustion during exercise. Recent evidence, and new lines of investigation, now place lactate as an active metabolite, capable of moving between cells, tissues and organs, where it may be oxidised as a fuel or reconverted to form pyruvate or glucose. The questions now to be asked concern the effects of lactate at the systemic and cellular level on metabolic processes. Does lactate act as a metabolic signal to specific tissues, becoming a metabolite pseudo-hormone? Does lactate have a role in whole-body coordination of sympathetic/parasympathetic nerve system control? And, finally, does lactate play a role in maintaining muscle excitability during intense muscle contraction? The concept of lactate acting as a signalling compound is a relatively new hypothesis stemming from a combination of comparative, cell and whole-organism investigations. It has been clearly demonstrated that lactate is capable of entering cells via the monocarboxylate transporter (MCT) protein shuttle system and that conversion of lactate to and from pyruvate is governed by specific lactate dehydrogenase isoforms, thereby forming a highly adaptable metabolic intermediate system. This review is structured in three sections, the first covering pertinent topics in lactate's history that led to the model of lactate as a waste product. The second section will discuss the potential of lactate as a signalling compound, and the third section will identify ways in which such a hypothesis might be investigated. In examining the history of lactate research, it appears that periods have occurred when advances in scientific techniques allowed investigation of this metabolite to expand. Similar to developments made first in the 1920s and then in the 1980s, contemporary advances in stable isotope, gene microarray and RNA interference technologies may allow the next stage of understanding of the role of this compound, so that, finally, the fundamental questions of lactate's role in whole-body and localised muscle function may be answered.
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Affiliation(s)
- Andrew Philp
- Department of Sport and Exercise Sciences, Chelsea School Research Centre, Welkin Performance Laboratories, Eastbourne, BN20 7SP, UK.
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Hashimoto T, Hussien R, Brooks GA. Colocalization of MCT1, CD147, and LDH in mitochondrial inner membrane of L6 muscle cells: evidence of a mitochondrial lactate oxidation complex. Am J Physiol Endocrinol Metab 2006; 290:E1237-44. [PMID: 16434551 DOI: 10.1152/ajpendo.00594.2005] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Results of previous studies suggested a role of mitochondria in intracellular and cell-cell lactate shuttles. Therefore, by using a rat-derived L6 skeletal muscle cell line and confocal laser-scanning microscopy (CLSM), we examined the cellular locations of mitochondria, lactate dehydrogenase (LDH), the lactate-pyruvate transporter MCT1, and CD147, a purported chaperone protein for MCT1. CLSM showed that LDH, MCT1, and CD147 are colocalized with the mitochondrial reticulum. Western blots showed that cytochrome oxidase (COX), NADH dehydrogenase, LDH, MCT1, and CD147 are abundant in mitochondrial fractions of L6 cells. Interactions among COX, MCT1, and CD147 in mitochondria were confirmed by immunoblotting after immunoprecipitation. These findings support the presence of a mitochondrial lactate oxidation complex associated with the COX end of the electron transport chain that might explain the oxidative catabolism of lactate and, hence, mechanism of the intracellular lactate shuttle.
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Affiliation(s)
- Takeshi Hashimoto
- Exercise Physiology Laboratory, Dept. of Integrative Biology, 5101 Valley Life Sciences Bldg., Univ. of California, Berkeley, CA 94720-3140, USA
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Ponsot E, Zoll J, N'guessan B, Ribera F, Lampert E, Richard R, Veksler V, Ventura-Clapier R, Mettauer B. Mitochondrial tissue specificity of substrates utilization in rat cardiac and skeletal muscles. J Cell Physiol 2005; 203:479-86. [PMID: 15521069 DOI: 10.1002/jcp.20245] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
As energetic metabolism is crucial for muscles, they develop different adaptations to respond to fluctuating demand among muscle types. Whereas quantitative characteristics are known, no study described simultaneously quantitative and qualitative differences among muscle types in terms of substrates utilization patterns. This study thus defined the pattern of substrates preferential utilization by mitochondria from glycolytic gastrocnemius (GAS) and oxidative soleus (SOL) skeletal muscles and from heart left ventrical (LV) in rats. We measured in situ, ADP (2 mM)-stimulated, mitochondrial respiration rates from skinned fibers in presence of increasing concentrations of pyruvate (Pyr) + malate (Mal), palmitoyl-carnitine (Palm-C) + Mal, glutamate (Glut) + Mal, glycerol-3-phosphate (G3-P), lactate (Lact) + Mal. Because the fibers oxygen uptake (Vs) followed Michaelis-Menten kinetics in function of substrates level we determined the Vs and Km, representing maximal oxidative capacity and the mitochondrial sensibility for each substrate, respectively. Vs were in the order GAS < SOL < LV for Pyr, Glu, and Palm-C substrates, whereas in the order SOL = LV < GAS with G3-P. Moreover, the relative capacity to oxidize Palm-C is extremely higher in LV than in SOL. Vs was not stimulated by the Lact substrate. The Km was equal for Pyr among muscles, but much lower for G3-P in GAS and lower for Palm-C in LV. These results demonstrate qualitative mitochondrial tissue specificity for metabolic pathways. Mitochondria of glycolytic muscle fibers are well adapted to play a central role for maintaining a satisfactory cytosolic redox state in these fibers, whereas mitochondria of LV developed important capacities to use fatty acids.
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Affiliation(s)
- E Ponsot
- Service des Explorations Fonctionnelles Respiratoires et de l'Exercice, Département de Physiologie, Strasbourg, France.
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