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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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Walsh MA, Musci RV, Jacobs RA, Hamilton KL. A practical perspective on how to develop, implement, execute, and reproduce high-resolution respirometry experiments: The physiologist's guide to an Oroboros O2k. FASEB J 2023; 37:e23280. [PMID: 37899680 DOI: 10.1096/fj.202301644rr] [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: 08/15/2023] [Revised: 09/29/2023] [Accepted: 10/13/2023] [Indexed: 10/31/2023]
Abstract
The development of high-resolution respirometry (HRR) has greatly expanded the analytical scope to study mitochondrial respiratory control relative to specific tissue/cell types across various metabolic states. Specifically, the Oroboros Oxygraph 2000 (O2k) is a common tool for measuring rates of mitochondrial respiration and is the focus of this perspective. The O2k platform is amenable for answering numerous bioenergetic questions. However, inherent variability with HRR-derived data, both within and amongst users, can impede progress in bioenergetics research. Therefore, we advocate for several vital considerations when planning and conducting O2k experiments to ultimately enhance transparency and reproducibility across laboratories. In this perspective, we offer guidance for best practices of mitochondrial preparation, protocol selection, and measures to increase reproducibility. The goal of this perspective is to propagate the use of the O2k, enhance reliability and validity for both new and experienced O2k users, and provide a reference for peer reviewers.
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Affiliation(s)
- Maureen A Walsh
- Health and Exercise Science Department, Colorado State University, Fort Collins, Colorado, USA
| | - Robert V Musci
- Health and Human Sciences Department, Loyola Marymount University, Los Angeles, California, USA
| | - Robert A Jacobs
- Department of Human Physiology and Nutrition, University of Colorado Colorado Springs (UCCS), Colorado Springs, Colorado, USA
- William J. Hybl Sports Medicine and Performance Center, Colorado Springs, Colorado, USA
| | - Karyn L Hamilton
- Health and Exercise Science Department, Colorado State University, Fort Collins, Colorado, USA
- Columbine Health Systems Center for Healthy Aging, Colorado State University, Fort Collins, Colorado, USA
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3
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Shastry A, Dunham-Snary K. Metabolomics and mitochondrial dysfunction in cardiometabolic disease. Life Sci 2023; 333:122137. [PMID: 37788764 DOI: 10.1016/j.lfs.2023.122137] [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: 08/01/2023] [Revised: 09/21/2023] [Accepted: 09/29/2023] [Indexed: 10/05/2023]
Abstract
Circulating metabolites are indicators of systemic metabolic dysfunction and can be detected through contemporary techniques in metabolomics. These metabolites are involved in numerous mitochondrial metabolic processes including glycolysis, fatty acid β-oxidation, and amino acid catabolism, and changes in the abundance of these metabolites is implicated in the pathogenesis of cardiometabolic diseases (CMDs). Epigenetic regulation and direct metabolite-protein interactions modulate metabolism, both within cells and in the circulation. Dysfunction of multiple mitochondrial components stemming from mitochondrial DNA mutations are implicated in disease pathogenesis. This review will summarize the current state of knowledge regarding: i) the interactions between metabolites found within the mitochondrial environment during CMDs, ii) various metabolites' effects on cellular and systemic function, iii) how harnessing the power of metabolomic analyses represents the next frontier of precision medicine, and iv) how these concepts integrate to expand the clinical potential for translational cardiometabolic medicine.
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Affiliation(s)
- Abhishek Shastry
- Department of Medicine, Queen's University, Kingston, ON, Canada
| | - Kimberly Dunham-Snary
- Department of Medicine, Queen's University, Kingston, ON, Canada; Department of Biomedical & Molecular Sciences, Queen's University, Kingston, ON, Canada.
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Kane DA, Foo ACY, Noftall EB, Brebner K, Marangoni DG. Lactate shuttling as an allostatic means of thermoregulation in the brain. Front Neurosci 2023; 17:1144639. [PMID: 37250407 PMCID: PMC10217782 DOI: 10.3389/fnins.2023.1144639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 04/18/2023] [Indexed: 05/31/2023] Open
Abstract
Lactate, the redox-balanced end product of glycolysis, travels within and between cells to fulfill an array of physiologic functions. While evidence for the centrality of this lactate shuttling in mammalian metabolism continues to mount, its application to physical bioenergetics remains underexplored. Lactate represents a metabolic "cul-de-sac," as it can only re-enter metabolism by first being converted back to pyruvate by lactate dehydrogenase (LDH). Given the differential distribution of lactate producing/consuming tissues during metabolic stresses (e.g., exercise), we hypothesize that lactate shuttling vis-à-vis the exchange of extracellular lactate between tissues serves a thermoregulatory function, i.e., an allostatic strategy to mitigate the consequences of elevated metabolic heat. To explore this idea, the rates of heat and respiratory oxygen consumption in saponin-permeabilized rat cortical brain samples fed lactate or pyruvate were measured. Heat and respiratory oxygen consumption rates, and calorespirometric ratios were lower during lactate vs. pyruvate-linked respiration. These results support the hypothesis of allostatic thermoregulation in the brain with lactate.
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Affiliation(s)
- Daniel A. Kane
- Department of Human Kinetics, St. Francis Xavier University, Antigonish, NS, Canada
| | - Alexander C. Y. Foo
- Department of Chemistry, St. Francis Xavier University, Antigonish, NS, Canada
| | - Erin B. Noftall
- Department of Human Kinetics, St. Francis Xavier University, Antigonish, NS, Canada
| | - Karen Brebner
- Department of Psychology, St. Francis Xavier University, Antigonish, NS, Canada
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Brooks GA, Osmond AD, Arevalo JA, Duong JJ, Curl CC, Moreno-Santillan DD, Leija RG. Lactate as a myokine and exerkine: drivers and signals of physiology and metabolism. J Appl Physiol (1985) 2023; 134:529-548. [PMID: 36633863 PMCID: PMC9970662 DOI: 10.1152/japplphysiol.00497.2022] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
No longer viewed as a metabolic waste product and cause of muscle fatigue, a contemporary view incorporates the roles of lactate in metabolism, sensing and signaling in normal as well as pathophysiological conditions. Lactate exists in millimolar concentrations in muscle, blood, and other tissues and can rise more than an order of magnitude as the result of increased production and clearance limitations. Lactate exerts its powerful driver-like influence by mass action, redox change, allosteric binding, and other mechanisms described in this article. Depending on the condition, such as during rest and exercise, following carbohydrate nutrition, injury, or pathology, lactate can serve as a myokine or exerkine with autocrine-, paracrine-, and endocrine-like functions that have important basic and translational implications. For instance, lactate signaling is: involved in reproductive biology, fueling the heart, muscle adaptation, and brain executive function, growth and development, and a treatment for inflammatory conditions. Lactate also works with many other mechanisms and factors in controlling cardiac output and pulmonary ventilation during exercise. Ironically, lactate can be disruptive of normal processes such as insulin secretion when insertion of lactate transporters into pancreatic β-cell membranes is not suppressed, and in carcinogenesis when factors that suppress carcinogenesis are inhibited, whereas factors that promote carcinogenesis are upregulated. Lactate signaling is important in areas of intermediary metabolism, redox biology, mitochondrial biogenesis, neurobiology, gut physiology, appetite regulation, nutrition, and overall health and vigor. The various roles of lactate as a myokine and exerkine are reviewed.NEW & NOTEWORTHY Lactate sensing and signaling is a relatively new and rapidly changing field. As a physiological signal lactate works both independently and in concert with other signals. Lactate operates via covalent binding and canonical signaling, redox change, and lactylation of DNA. Lactate can also serve as an element of feedback loops in cardiopulmonary regulation. From conception through aging lactate is not the only a myokine or exerkine, but it certainly deserves consideration as a physiological signal.
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Affiliation(s)
- George A Brooks
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California, United States
| | - Adam D Osmond
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California, United States
| | - Jose A Arevalo
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California, United States
| | - Justin J Duong
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California, United States
| | - Casey C Curl
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California, United States
| | - Diana D Moreno-Santillan
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California, United States
| | - Robert G Leija
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California, United States
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Batterson PM, McGowan EM, Stierwalt HD, Ehrlicher SE, Newsom SA, Robinson MM. Two weeks of high-intensity interval training increases skeletal muscle mitochondrial respiration via complex-specific remodeling in sedentary humans. J Appl Physiol (1985) 2023; 134:339-355. [PMID: 36603044 DOI: 10.1152/japplphysiol.00467.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Aerobic training remodels the quantity and quality (function per unit) of skeletal muscle mitochondria to promote substrate oxidation, however, there remain key gaps in understanding the underlying mechanisms during initial training adaptations. We used short-term high-intensity interval training (HIIT) to determine changes to mitochondrial respiration and regulatory pathways that occur early in remodeling. Fifteen normal-weight sedentary adults started seven sessions of HIIT over 14 days and 14 participants completed the intervention. We collected vastus lateralis biopsies before and 48 h after HIIT to determine mitochondrial respiration, RNA sequencing, and Western blotting for proteins of mitochondrial respiration and degradation via autophagy. HIIT increased respiration per mitochondrial protein for lipid (+23% P = 0.020), complex I (+18%, P = 0.0015), complex I + II (+14%, P < 0.0001), and complex II (+24% P < 0.0001). Transcripts that increased with HIIT identified several gene sets of mitochondrial respiration, particularly for complex I, whereas transcripts that decreased identified pathways of DNA and chromatin remodeling. HIIT lowered protein abundance of autophagy markers for p62 (-19%, P = 0.012) and LC3 II/I (-20%, P = 0.004) in whole tissue lysates but not isolated mitochondria. Meal tolerance testing revealed HIIT increased the change in whole body respiratory exchange ratio and lowered cumulative plasma insulin concentrations. Gene transcripts and respiratory function indicate remodeling of mitochondria within 2 wk of HIIT. Overall changes are consistent with increased protein quality driving rapid improvements in substrate oxidation.NEW & NOTEWORTHY Aerobic training stimulates mitochondrial metabolism in skeletal muscle that is linked to improvements to whole body fuel metabolism. The mechanisms driving changes to the quantity and quality (function per unit) of mitochondria are less known. We used seven sessions of high-intensity interval training (HIIT) to determine functional changes and mechanisms of mitochondrial remodeling in skeletal muscle. HIIT increased mitochondrial respiration per mass for fatty acids, complex I, and complex II substrates. HIIT-induced remodeling pathways including gene transcripts for mitochondrial respiration (via RNA sequencing of muscle tissue) and proteins related to complex I respiration. We conclude that an early feature of aerobic training is increased mitochondrial protein quality via improved respiration and induction of mitochondrial transcriptional patterns.
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Affiliation(s)
- Philip M Batterson
- School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon
| | - Erin M McGowan
- School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon
| | - Harrison D Stierwalt
- School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon
| | - Sarah E Ehrlicher
- School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon
| | - Sean A Newsom
- School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon
| | - Matthew M Robinson
- School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, Oregon
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7
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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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8
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Huynh KW, Pamenter ME. Lactate inhibits naked mole-rat cardiac mitochondrial respiration. J Comp Physiol B 2022; 192:501-511. [PMID: 35181821 DOI: 10.1007/s00360-022-01430-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 01/13/2022] [Accepted: 01/29/2022] [Indexed: 12/25/2022]
Abstract
In aerobic conditions, the proton-motive force drives oxidative phosphorylation (OXPHOS) and the conversion of ADP to ATP. In hypoxic environments, OXPHOS is impaired, resulting in energy shortfalls and the accumulation of protons and lactate. This results in cellular acidification, which may impact the activity and/or integrity of mitochondrial enzymes and in turn negatively impact mitochondrial respiration and thus aerobic ATP production. Naked mole-rats (NMRs) are among the most hypoxia-tolerant mammals and putatively experience intermittent hypoxia in their underground burrows. However, if and how NMR cardiac mitochondria are impacted by lactate accumulation in hypoxia is unknown. We predicted that lactate alters mitochondrial respiration in NMR cardiac muscle. To test this, we used high-resolution respirometry to measure mitochondrial respiration in permeabilized cardiac muscle fibres from NMRs exposed to 4 h of in vivo normoxia (21% O2) or hypoxia (7% O2). We found that: (1) cardiac mitochondria cannot directly oxidize lactate, but surprisingly, (2) lactate inhibits mitochondrial respiration, and (3) decreases complex IV maximum respiratory capacity. Finally, (4) in vivo hypoxic exposure decreases the magnitude of lactate-mediated inhibition of mitochondrial respiration. Taken together, our results suggest that lactate may retard electron transport system function in NMR cardiac mitochondria, particularly in normoxia, and that NMR hearts may be primed for anaerobic metabolism.
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Affiliation(s)
- Kenny W Huynh
- Department of Biology, University of Ottawa, 30 Marie Curie Pvt., Ottawa, ON, K1N 6N5, Canada
| | - Matthew E Pamenter
- Department of Biology, University of Ottawa, 30 Marie Curie Pvt., Ottawa, ON, K1N 6N5, Canada. .,University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada.
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9
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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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10
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Kominami K, Nishijima H, Imahashi K, Katsuragawa T, Murakami M, Akino M. Gas exchange threshold to guide exercise training intensity of older individuals during cardiac rehabilitation. Medicine (Baltimore) 2021; 100:e27540. [PMID: 34678888 PMCID: PMC8542148 DOI: 10.1097/md.0000000000027540] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 09/29/2021] [Indexed: 01/05/2023] Open
Abstract
The gas exchange threshold (GET), which is determined during incremental exercise (Inc-Ex) testing, is often considered a safe training intensity for cardiac rehabilitation. However, there are only a limited number of reports on the actual implementation of this method. We assessed the applicability of GET-guided exercise using a constant load exercise (CL-Ex) protocol.We recruited 20 healthy older individuals (healthy, age: 69.4 ± 6.8 years) and 10 patients with cardiovascular diseases or risk factors (patient, age: 73.0 ± 8.8 years). On day 1, we determined the GET during symptomatic maximal Inc-Ex. On day 2, CL-Ex at work rate (watt: W) where the GET manifested during Inc-Ex (therefore, not corrected for the known oxygen response delay) was maintained for 20 minute. Arterialized blood lactate (BLa) levels were also determined.Oxygen uptake reached a steady state in all participants, with a mean respiratory exchange ratio of < 1.0. The mean BLa at the GET during Inc-Ex was 1.51 ± .29 mmol·l-1 in the healthy group and 1.78 ± .42 mmol·L-1 in the patient group, which was about .5 mmol·L-1 above the resting level. During CL-Ex, BLa increased significantly over the value at the GET (Inc-Ex). However, it reached a steady-state level of 2.65 ± 1.56 (healthy) and 2.53 ± 0.95 (patient) mmol·L-1. The %peak oxygen uptake, %peak heart rate, and %heart rate reserve during CL-Ex were 58.8 ± 11.5, 71.8 ± 10.3, and 44.9 ± 17.4, respectively. All participants could complete CL-Ex with mean perceived exertion ratings (Borg/20) of 11.8 ± 1.3 (healthy) and 12.2 ± 1.3 (patient). These heart rate-related indices and exertion ratings were all within the recommended international guidelines for cardiac rehabilitation.CL-Ex at the GET appears to be the optimal exercise intensity for cardiac rehabilitation.
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Affiliation(s)
- Kazuyuki Kominami
- Cardiac Rehabilitation Center, Sapporo Ryokuai Hospital, Sapporo, Japan
| | - Hirotaka Nishijima
- Cardiac Rehabilitation Center, Sapporo Ryokuai Hospital, Sapporo, Japan
- Department of Cardiovascular Medicine, Sapporo Ryokuai Hospital, Sapporo, Japan
| | - Keiko Imahashi
- Cardiac Rehabilitation Center, Sapporo Ryokuai Hospital, Sapporo, Japan
| | - Toko Katsuragawa
- Cardiac Rehabilitation Center, Sapporo Ryokuai Hospital, Sapporo, Japan
| | - Mitsuyo Murakami
- Cardiac Rehabilitation Center, Sapporo Ryokuai Hospital, Sapporo, Japan
| | - Masatoshi Akino
- Cardiac Rehabilitation Center, Sapporo Ryokuai Hospital, Sapporo, Japan
- Department of Cardiovascular Medicine, Sapporo Ryokuai Hospital, Sapporo, Japan
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11
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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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12
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Koons A, Amaducci AM, Katz KD. Reversible Total Vision Loss Caused by Severe Metformin-associated Lactic Acidosis: A Case Report. Clin Pract Cases Emerg Med 2021; 5:206-209. [PMID: 34437006 PMCID: PMC8143825 DOI: 10.5811/cpcem.2021.3.51141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 03/05/2021] [Indexed: 11/25/2022] Open
Abstract
Introduction Metformin is a biguanide used to treat diabetes mellitus (DM). Metformin-associated lactic acidosis (MALA) carries a high mortality and can occur in patients with renal failure from drug bioaccumulation. Reversible vision loss is a highly unusual, rarely reported complication of MALA. We present a case of a patient whose serum metformin concentration was unusually high and associated with vision loss. Case Report A 60-year-old woman presented to an outside hospital emergency department with acute vision loss after being found at home confused, somnolent, and hypoglycemic, having last being seen normal two days prior. She reported vomiting and diarrhea during that time and a recently treated urinary tract infection. The visual loss resolved with continuous renal replacement therapy. Conclusion This novel case of a patient with Type II DM prescribed metformin and insulin who developed reversible vision loss while suffering from MALA highlights the potential for vision loss in association with MALA.
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Affiliation(s)
- Andrew Koons
- Lehigh Valley Health Network, Department of Emergency and Hospital Medicine, Allentown, Pennsylvania
| | - Alexandra M Amaducci
- Lehigh Valley Health Network, Department of Emergency and Hospital Medicine, Allentown, Pennsylvania
| | - Kenneth D Katz
- Lehigh Valley Health Network, Department of Emergency and Hospital Medicine, Allentown, Pennsylvania
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13
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Jacobs RA, Lundby C. Contextualizing the biological relevance of standardized high-resolution respirometry to assess mitochondrial function in permeabilized human skeletal muscle. Acta Physiol (Oxf) 2021; 231:e13625. [PMID: 33570804 PMCID: PMC8047922 DOI: 10.1111/apha.13625] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 12/16/2022]
Abstract
Aim This study sought to provide a statistically robust reference for measures of mitochondrial function from standardized high‐resolution respirometry with permeabilized human skeletal muscle (ex vivo), compare analogous values obtained via indirect calorimetry, arterial‐venous O2 differences and 31P magnetic resonance spectroscopy (in vivo) and attempt to resolve differences across complementary methodologies as necessary. Methods Data derived from 831 study participants across research published throughout March 2009 to November 2019 were amassed to examine the biological relevance of ex vivo assessments under standard conditions, ie physiological temperatures of 37°C and respiratory chamber oxygen concentrations of ~250 to 500 μmol/L. Results Standard ex vivo‐derived measures are lower (Z ≥ 3.01, P ≤ .0258) en masse than corresponding in vivo‐derived values. Correcting respiratory values to account for mitochondrial temperatures 10°C higher than skeletal muscle temperatures at maximal exercise (~50°C): (i) transforms data to resemble (Z ≤ 0.8, P > .9999) analogous yet context‐specific in vivo measures, eg data collected during maximal 1‐leg knee extension exercise; and (ii) supports the position that maximal skeletal muscle respiratory rates exceed (Z ≥ 13.2, P < .0001) those achieved during maximal whole‐body exercise, e.g. maximal cycling efforts. Conclusion This study outlines and demonstrates necessary considerations when actualizing the biological relevance of human skeletal muscle respiratory control, metabolic flexibility and bioenergetics from standard ex vivo‐derived assessments using permeabilized human muscle. These findings detail how cross‐procedural comparisons of human skeletal muscle mitochondrial function may be collectively scrutinized in their relationship to human health and lifespan.
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Affiliation(s)
- Robert A. Jacobs
- Department of Human Physiology & Nutrition University of Colorado Colorado Springs (UCCS) Colorado Springs CO USA
| | - Carsten Lundby
- Innland University of Applied Sciences Lillehammer Norway
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14
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Kiran D, Basaraba RJ. Lactate Metabolism and Signaling in Tuberculosis and Cancer: A Comparative Review. Front Cell Infect Microbiol 2021; 11:624607. [PMID: 33718271 PMCID: PMC7952876 DOI: 10.3389/fcimb.2021.624607] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 01/13/2021] [Indexed: 12/16/2022] Open
Abstract
Infection with Mycobacterium tuberculosis (Mtb) leading to tuberculosis (TB) disease continues to be a major global health challenge. Critical barriers, including but not limited to the development of multi-drug resistance, lack of diagnostic assays that detect patients with latent TB, an effective vaccine that prevents Mtb infection, and infectious and non-infectious comorbidities that complicate active TB, continue to hinder progress toward a TB cure. To complement the ongoing development of new antimicrobial drugs, investigators in the field are exploring the value of host-directed therapies (HDTs). This therapeutic strategy targets the host, rather than Mtb, and is intended to augment host responses to infection such that the host is better equipped to prevent or clear infection and resolve chronic inflammation. Metabolic pathways of immune cells have been identified as promising HDT targets as more metabolites and metabolic pathways have shown to play a role in TB pathogenesis and disease progression. Specifically, this review highlights the potential role of lactate as both an immunomodulatory metabolite and a potentially important signaling molecule during the host response to Mtb infection. While long thought to be an inert end product of primarily glucose metabolism, the cancer research field has discovered the importance of lactate in carcinogenesis and resistance to chemotherapeutic drug treatment. Herein, we discuss similarities between the TB granuloma and tumor microenvironments in the context of lactate metabolism and identify key metabolic and signaling pathways that have been shown to play a role in tumor progression but have yet to be explored within the context of TB. Ultimately, lactate metabolism and signaling could be viable HDT targets for TB; however, critical additional research is needed to better understand the role of lactate at the host-pathogen interface during Mtb infection before adopting this HDT strategy.
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Affiliation(s)
| | - Randall J. Basaraba
- Metabolism of Infectious Diseases Laboratory, Mycobacteria Research Laboratories, Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States
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15
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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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16
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Xu P, Xu W, Gao S, Che Y, Zhao P, Lu S, Wang Y, Chen X, Zhang Q, Chen J, Zheng X, Huang G, He G, Liu X. Global metabolic profiling of hemorrhagic shock and resuscitation. Biomed Chromatogr 2021; 35:e5044. [PMID: 33283298 DOI: 10.1002/bmc.5044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 11/24/2020] [Accepted: 12/01/2020] [Indexed: 11/11/2022]
Abstract
Hemorrhagic shock (HS) is a medical emergency during trauma. Significant loss of tissue perfusion may result in cellular hypoxia, organ damage and death. The primary treatment of HS is control of the source of bleeding as soon as possible and fluid replacement (crystalloid solutions and blood transfusion). Metabolomics can identify novel biomarkers for various functional and organic diseases. Therefore, systematic exploration of the biological mechanisms of HS and blood transfusion enables the optimization of treatments for HS to reduce the occurrence of organ damage. In this study, a global metabolic profiling strategy is applied to evaluate metabolic changes in the HS rat model. A serum metabolic network with 58 significant metabolites was constructed for HS and resuscitation. Our investigation will offer insights into the pathogenesis.
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Affiliation(s)
- Ping Xu
- Clinical Research Centre, Shanghai Baoshan Luodian Hospital, Shanghai University, Shanghai, China
| | - Wei Xu
- Clinical Research Centre, Shanghai Baoshan Luodian Hospital, Shanghai University, Shanghai, China
| | - Songyan Gao
- Institute of Translation Medicine, Shanghai University, Shanghai, China.,Luodian Clinical Drug Research Centre, Institute for Translational Medicine Research, Shanghai University, Shanghai, China
| | - Yanting Che
- Institute of Translation Medicine, Shanghai University, Shanghai, China.,Luodian Clinical Drug Research Centre, Institute for Translational Medicine Research, Shanghai University, Shanghai, China
| | - Ping Zhao
- Clinical Research Centre, Shanghai Baoshan Luodian Hospital, Shanghai University, Shanghai, China
| | - Shengfang Lu
- Clinical Research Centre, Shanghai Baoshan Luodian Hospital, Shanghai University, Shanghai, China
| | - Yong Wang
- Clinical Research Centre, Shanghai Baoshan Luodian Hospital, Shanghai University, Shanghai, China
| | - Xiaoqing Chen
- Institute of Translation Medicine, Shanghai University, Shanghai, China.,Luodian Clinical Drug Research Centre, Institute for Translational Medicine Research, Shanghai University, Shanghai, China
| | - Qun Zhang
- Baoshan Geriatric Nursing Hospital, Shanghai, China
| | - Junjie Chen
- Institute of Translation Medicine, Shanghai University, Shanghai, China.,Luodian Clinical Drug Research Centre, Institute for Translational Medicine Research, Shanghai University, Shanghai, China
| | | | - Gang Huang
- Department of Urology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Guibing He
- Clinical Research Centre, Shanghai Baoshan Luodian Hospital, Shanghai University, Shanghai, China
| | - Xinru Liu
- Institute of Translation Medicine, Shanghai University, Shanghai, China.,Luodian Clinical Drug Research Centre, Institute for Translational Medicine Research, Shanghai University, Shanghai, China
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17
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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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18
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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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19
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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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20
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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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21
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Ørtenblad N, Nielsen J, Boushel R, Söderlund K, Saltin B, Holmberg HC. The Muscle Fiber Profiles, Mitochondrial Content, and Enzyme Activities of the Exceptionally Well-Trained Arm and Leg Muscles of Elite Cross-Country Skiers. Front Physiol 2018; 9:1031. [PMID: 30116201 PMCID: PMC6084043 DOI: 10.3389/fphys.2018.01031] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 07/11/2018] [Indexed: 01/11/2023] Open
Abstract
As one of the most physically demanding sports in the Olympic Games, cross-country skiing poses considerable challenges with respect to both force generation and endurance during the combined upper- and lower-body effort of varying intensity and duration. The isoforms of myosin in skeletal muscle have long been considered not only to define the contractile properties, but also to determine metabolic capacities. The current investigation was designed to explore the relationship between these isoforms and metabolic profiles in the arms (triceps brachii) and legs (vastus lateralis) as well as the range of training responses in the muscle fibers of elite cross-country skiers with equally and exceptionally well-trained upper and lower bodies. The proportion of myosin heavy chain (MHC)-1 was higher in the leg (58 ± 2% [34-69%]) than arm (40 ± 3% [24-57%]), although the mitochondrial volume percentages [8.6 ± 1.6 (leg) and 9.0 ± 2.0 (arm)], and average number of capillaries per fiber [5.8 ± 0.8 (leg) and 6.3 ± 0.3 (arm)] were the same. In these comparable highly trained leg and arm muscles, the maximal citrate synthase (CS) activity was the same. Still, 3-hydroxy-acyl-CoA-dehydrogenase (HAD) capacity was 52% higher (P < 0.05) in the leg compared to arm muscles, suggesting a relatively higher capacity for lipid oxidation in leg muscle, which cannot be explained by the different fiber type distributions. For both limbs combined, HAD activity was correlated with the content of MHC-1 (r2 = 0.32, P = 0.011), whereas CS activity was not. Thus, in these highly trained cross-country skiers capillarization of and mitochondrial volume in type 2 fiber can be at least as high as in type 1 fibers, indicating a divergence between fiber type pattern and aerobic metabolic capacity. The considerable variability in oxidative metabolism with similar MHC profiles provides a new perspective on exercise training. Furthermore, the clear differences between equally well-trained arm and leg muscles regarding HAD activity cannot be explained by training status or MHC distribution, thereby indicating an intrinsic metabolic difference between the upper and lower body. Moreover, trained type 1 and type 2A muscle fibers exhibited similar aerobic capacity regardless of whether they were located in an arm or leg muscle.
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Affiliation(s)
- Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster, University of Southern Denmark, Odense, Denmark.,School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Joachim Nielsen
- Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster, University of Southern Denmark, Odense, Denmark
| | - Robert Boushel
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Karin Söderlund
- Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Bengt Saltin
- Copenhagen Muscle Research Centre, Copenhagen, Denmark
| | - Hans-Christer Holmberg
- Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden.,School of Sport Sciences, UiT The Arctic University of Norway, Tromsø, Norway
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22
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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: 614] [Impact Index Per Article: 102.3] [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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23
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Chondronikola M, Magkos F, Yoshino J, Okunade AL, Patterson BW, Muehlbauer MJ, Newgard CB, Klein S. Effect of Progressive Weight Loss on Lactate Metabolism: A Randomized Controlled Trial. Obesity (Silver Spring) 2018; 26:683-688. [PMID: 29476613 PMCID: PMC5866193 DOI: 10.1002/oby.22129] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 12/13/2017] [Accepted: 12/26/2017] [Indexed: 02/01/2023]
Abstract
OBJECTIVE Lactate is an intermediate of glucose metabolism that has been implicated in the pathogenesis of insulin resistance. This study evaluated the relationship between glucose kinetics and plasma lactate concentration ([LAC]) before and after manipulating insulin sensitivity by progressive weight loss. METHODS Forty people with obesity (BMI = 37.9 ± 4.3 kg/m2 ) were randomized to weight maintenance (n = 14) or weight loss (n = 19). Subjects were studied before and after 6 months of weight maintenance and before and after 5%, 11%, and 16% weight loss. A hyperinsulinemic-euglycemic clamp procedure in conjunction with [6,6-2 H2 ]glucose tracer infusion was used to assess glucose kinetics. RESULTS At baseline, fasting [LAC] correlated positively with endogenous glucose production rate (r = 0.532; P = 0.001) and negatively with insulin sensitivity, assessed as the insulin-stimulated glucose disposal (r = -0.361; P = 0.04). Progressive (5% through 16%) weight loss caused a progressive decrease in fasting [LAC], and the decrease in fasting [LAC] after 5% weight loss was correlated with the decrease in endogenous glucose production (r = 0.654; P = 0.002) and the increase in insulin sensitivity (r = -0.595; P = 0.007). CONCLUSIONS This study demonstrates the interrelationships among weight loss, hepatic and muscle glucose kinetics, insulin sensitivity, and [LAC], and it suggests that [LAC] can serve as an additional biomarker of glucose-related insulin resistance.
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Affiliation(s)
- Maria Chondronikola
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Faidon Magkos
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St. Louis, MO, USA
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore & Clinical Nutrition Research Centre, A*STAR, Singapore
| | - Jun Yoshino
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Adewole L. Okunade
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Bruce W. Patterson
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Michael J. Muehlbauer
- Sarah W. Stedman Nutrition and Metabolism Center & Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC, USA
| | - Christopher B. Newgard
- Sarah W. Stedman Nutrition and Metabolism Center & Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC, USA
| | - Samuel Klein
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St. Louis, MO, USA
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24
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Buckel W, Thauer RK. Flavin-Based Electron Bifurcation, A New Mechanism of Biological Energy Coupling. Chem Rev 2018; 118:3862-3886. [PMID: 29561602 DOI: 10.1021/acs.chemrev.7b00707] [Citation(s) in RCA: 189] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
There are two types of electron bifurcation (EB), either quinone- or flavin-based (QBEB/FBEB), that involve reduction of a quinone or flavin by a two-electron transfer and two reoxidations by a high- and low-potential one-electron acceptor with a reactive semiquinone intermediate. In QBEB, the reduced low-potential acceptor (cytochrome b) is exclusively used to generate ΔμH+. In FBEB, the "energy-rich" low-potential reduced ferredoxin or flavodoxin has dual function. It can give rise to ΔμH+/Na+ via a ferredoxin:NAD reductase (Rnf) or ferredoxin:proton reductase (Ech) or conducts difficult reductions such as CO2 to CO. The QBEB membrane complexes are similar in structure and function and occur in all domains of life. In contrast, FBEB complexes are soluble and occur only in strictly anaerobic bacteria and archaea (FixABCX being an exception). The FBEB complexes constitute a group consisting of four unrelated families that contain (1) electron-transferring flavoproteins (EtfAB), (2) NAD(P)H dehydrogenase (NuoF homologues), (3) heterodisulfide reductase (HdrABC) or HdrABC homologues, and (4) NADH-dependent ferredoxin:NADP reductase (NfnAB). The crystal structures and electron transport of EtfAB-butyryl-CoA dehydrogenase and NfnAB are compared with those of complex III of the respiratory chain (cytochrome bc1), whereby unexpected common features have become apparent.
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Affiliation(s)
- Wolfgang Buckel
- Fachbereich Biologie , Philipps-Universität , 35032 Marburg , Germany.,Max-Planck-Institut für Terrestrische Mikrobiologie , 35043 Marburg , Germany
| | - Rudolf K Thauer
- Fachbereich Biologie , Philipps-Universität , 35032 Marburg , Germany.,Max-Planck-Institut für Terrestrische Mikrobiologie , 35043 Marburg , Germany
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Buckel W, Thauer RK. Flavin-Based Electron Bifurcation, Ferredoxin, Flavodoxin, and Anaerobic Respiration With Protons (Ech) or NAD + (Rnf) as Electron Acceptors: A Historical Review. Front Microbiol 2018; 9:401. [PMID: 29593673 PMCID: PMC5861303 DOI: 10.3389/fmicb.2018.00401] [Citation(s) in RCA: 182] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Accepted: 02/21/2018] [Indexed: 12/19/2022] Open
Abstract
Flavin-based electron bifurcation is a newly discovered mechanism, by which a hydride electron pair from NAD(P)H, coenzyme F420H2, H2, or formate is split by flavoproteins into one-electron with a more negative reduction potential and one with a more positive reduction potential than that of the electron pair. Via this mechanism microorganisms generate low- potential electrons for the reduction of ferredoxins (Fd) and flavodoxins (Fld). The first example was described in 2008 when it was found that the butyryl-CoA dehydrogenase-electron-transferring flavoprotein complex (Bcd-EtfAB) of Clostridium kluyveri couples the endergonic reduction of ferredoxin (E0′ = −420 mV) with NADH (−320 mV) to the exergonic reduction of crotonyl-CoA to butyryl-CoA (−10 mV) with NADH. The discovery was followed by the finding of an electron-bifurcating Fd- and NAD-dependent [FeFe]-hydrogenase (HydABC) in Thermotoga maritima (2009), Fd-dependent transhydrogenase (NfnAB) in various bacteria and archaea (2010), Fd- and H2-dependent heterodisulfide reductase (MvhADG-HdrABC) in methanogenic archaea (2011), Fd- and NADH-dependent caffeyl-CoA reductase (CarCDE) in Acetobacterium woodii (2013), Fd- and NAD-dependent formate dehydrogenase (HylABC-FdhF2) in Clostridium acidi-urici (2013), Fd- and NADP-dependent [FeFe]-hydrogenase (HytA-E) in Clostridium autoethanogrenum (2013), Fd(?)- and NADH-dependent methylene-tetrahydrofolate reductase (MetFV-HdrABC-MvhD) in Moorella thermoacetica (2014), Fd- and NAD-dependent lactate dehydrogenase (LctBCD) in A. woodii (2015), Fd- and F420H2-dependent heterodisulfide reductase (HdrA2B2C2) in Methanosarcina acetivorans (2017), and Fd- and NADH-dependent ubiquinol reductase (FixABCX) in Azotobacter vinelandii (2017). The electron-bifurcating flavoprotein complexes known to date fall into four groups that have evolved independently, namely those containing EtfAB (CarED, LctCB, FixBA) with bound FAD, a NuoF homolog (HydB, HytB, or HylB) harboring FMN, NfnB with bound FAD, or HdrA harboring FAD. All these flavoproteins are cytoplasmic except for the membrane-associated protein FixABCX. The organisms—in which they have been found—are strictly anaerobic microorganisms except for the aerobe A. vinelandii. The electron-bifurcating complexes are involved in a variety of processes such as butyric acid fermentation, methanogenesis, acetogenesis, anaerobic lactate oxidation, dissimilatory sulfate reduction, anaerobic- dearomatization, nitrogen fixation, and CO2 fixation. They contribute to energy conservation via the energy-converting ferredoxin: NAD+ reductase complex Rnf or the energy-converting ferredoxin-dependent hydrogenase complex Ech. This Review describes how this mechanism was discovered.
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Affiliation(s)
- Wolfgang Buckel
- Laboratory for Microbiology, Faculty of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Rudolf K Thauer
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
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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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Wang ZY, Liu YY, Liu GH, Lu HB, Mao CY. l-Carnitine and heart disease. Life Sci 2017; 194:88-97. [PMID: 29241711 DOI: 10.1016/j.lfs.2017.12.015] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 12/03/2017] [Accepted: 12/09/2017] [Indexed: 02/07/2023]
Abstract
Cardiovascular disease (CVD) is a key cause of deaths worldwide, comprising 15-17% of healthcare expenditure in developed countries. Current records estimate an annual global average of 30 million cardiac dysfunction cases, with a predicted escalation by two-three folds for the next 20-30years. Although β-blockers and angiotensin-converting-enzymes are commonly prescribed to control CVD risk, hepatotoxicity and hematological changes are frequent adverse events associated with these drugs. Search for alternatives identified endogenous cofactor l-carnitine, which is capable of promoting mitochondrial β-oxidation towards a balanced cardiac energy metabolism. l-Carnitine facilitates transport of long-chain fatty acids into the mitochondrial matrix, triggering cardioprotective effects through reduced oxidative stress, inflammation and necrosis of cardiac myocytes. Additionally, l-carnitine regulates calcium influx, endothelial integrity, intracellular enzyme release and membrane phospholipid content for sustained cellular homeostasis. Carnitine depletion, characterized by reduced expression of "organic cation transporter-2" gene, is a metabolic and autosomal recessive disorder that also frequently associates with CVD. Hence, exogenous carnitine administration through dietary and intravenous routes serves as a suitable protective strategy against ventricular dysfunction, ischemia-reperfusion injury, cardiac arrhythmia and toxic myocardial injury that prominently mark CVD. Additionally, carnitine reduces hypertension, hyperlipidemia, diabetic ketoacidosis, hyperglycemia, insulin-dependent diabetes mellitus, insulin resistance, obesity, etc. that enhance cardiovascular pathology. These favorable effects of l-carnitine have been evident in infants, juvenile, young, adult and aged patients of sudden and chronic heart failure as well. This review describes the mechanism of action, metabolism and pharmacokinetics of l-carnitine. It specifically emphasizes upon the beneficial role of l-carnitine in cardiomyopathy.
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Affiliation(s)
- Zhong-Yu Wang
- Department of Cardiology, China-Japan Union Hospital, Jilin University, Changchun, PR China
| | - Ying-Yi Liu
- Department of Anesthesia, China-Japan Union Hospital, Jilin University, Changchun, PR China
| | - Guo-Hui Liu
- Department of Cardiology, China-Japan Union Hospital, Jilin University, Changchun, PR China
| | - Hai-Bin Lu
- College of Pharmacy, Jilin University, Changchun, PR China
| | - Cui-Ying Mao
- Department of Cardiology, China-Japan Union Hospital, Jilin University, Changchun, PR China.
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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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Yu Y, Wang L, Delguste F, Durand A, Guilbaud A, Rousselin C, Schmidt AM, Tessier F, Boulanger E, Neviere R. Advanced glycation end products receptor RAGE controls myocardial dysfunction and oxidative stress in high-fat fed mice by sustaining mitochondrial dynamics and autophagy-lysosome pathway. Free Radic Biol Med 2017; 112:397-410. [PMID: 28826719 DOI: 10.1016/j.freeradbiomed.2017.08.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 08/05/2017] [Accepted: 08/17/2017] [Indexed: 12/18/2022]
Abstract
Oxidative stress and mitochondrial dysfunction are recognized as major contributors of cardiovascular damage in diabetes and high fat diet (HFD) fed mice. Blockade of receptor for advanced glycation end products (RAGE) attenuates vascular oxidative stress and development of atherosclerosis. We tested whether HFD-induced myocardial dysfunction would be reversed in RAGE deficiency mice, in association with changes in oxidative stress damage, mitochondrial respiration, mitochondrial fission and autophagy-lysosomal pathway. Cardiac antioxidant capacity was upregulated in RAGE-/- mice under normal diet as evidenced by increased superoxide dismutase and sirtuin mRNA expressions. Mitochondrial fragmentation and mitochondrial fission protein Drp1 and Fis1 expressions were increased in RAGE-/- mice. Autophagy-related protein expressions and cathepsin-L activity were increased in RAGE-/- mice suggesting sustained autophagy-lysosomal flux. HFD induced mitochondrial respiration defects, cardiac contractile dysfunction, disrupted mitochondrial dynamics and autophagy inhibition, which were partially prevented in RAGE-/- mice. Our results suggest that cardioprotection against HFD in RAGE-/- mice include reactivation of autophagy, as inhibition of autophagic flux by chloroquine fully abrogated beneficial myocardial effects and its stimulation by rapamycin improved myocardial function in HFD wild type mice. As mitochondrial fission is necessary to mitophagy, increased fragmentation of mitochondrial network in HFD RAGE-/- mice may have facilitated removal of damaged mitochondria leading to better mitochondrial quality control. In conclusion, modulation of RAGE pathway may improve mitochondrial damage and myocardial dysfunction in HFD mice. Attenuation of cardiac oxidative stress and maintenance of healthy mitochondria population ensuring adequate energy supply may be involved in myocardial protection against HFD.
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Affiliation(s)
- Yichi Yu
- INSERM U995, LIRIC /Team "Glycation: from inflammation to aging", Lille University, France; School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Lei Wang
- INSERM U995, LIRIC /Team "Glycation: from inflammation to aging", Lille University, France; School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Florian Delguste
- INSERM U995, LIRIC /Team "Glycation: from inflammation to aging", Lille University, France
| | - Arthur Durand
- INSERM U995, LIRIC /Team "Glycation: from inflammation to aging", Lille University, France; University Hospital CHU of Lille, F-59000 Lille, France
| | - Axel Guilbaud
- INSERM U995, LIRIC /Team "Glycation: from inflammation to aging", Lille University, France
| | - Clementine Rousselin
- INSERM U995, LIRIC /Team "Glycation: from inflammation to aging", Lille University, France; University Hospital CHU of Lille, F-59000 Lille, France
| | - Ann Marie Schmidt
- Diabetes Research Center, Department of Medicine, NYU Langone Medical Center, New York, NY, USA
| | - Frédéric Tessier
- INSERM U995, LIRIC /Team "Glycation: from inflammation to aging", Lille University, France
| | - Eric Boulanger
- INSERM U995, LIRIC /Team "Glycation: from inflammation to aging", Lille University, France; University Hospital CHU of Lille, F-59000 Lille, France
| | - Remi Neviere
- INSERM U995, LIRIC /Team "Glycation: from inflammation to aging", Lille University, France; University Hospital CHU of Martinique, University of Antilles, Fort de France F-97200, France.
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Mohr M, Nielsen TS, Weihe P, Thomsen JA, Aquino G, Krustrup P, Nordsborg NB. Muscle ion transporters and antioxidative proteins have different adaptive potential in arm than in leg skeletal muscle with exercise training. Physiol Rep 2017; 5:5/19/e13470. [PMID: 29038365 PMCID: PMC5641943 DOI: 10.14814/phy2.13470] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 09/07/2017] [Accepted: 09/11/2017] [Indexed: 11/24/2022] Open
Abstract
It was evaluated whether upper‐body compared to lower‐body musculature exhibits a different phenotype in relation to capacity for handling reactive oxygen species (ROS), H+, La−, Na+, K+ and also whether it differs in adaptive potential to exercise training. Eighty‐three sedentary premenopausal women aged 45 ± 6 years (mean ± SD) were randomized into a high‐intensity intermittent swimming group (HIS, n = 21), a moderate‐intensity swimming group (MOS, n = 21), a soccer group (SOC, n = 21), or a control group (CON, n = 20). Intervention groups completed three weekly training sessions for 15 weeks, and pre‐ and postintervention biopsies were obtained from deltoideus and vastus lateralis muscle. Before training, monocarboxylate transporter 4 (MCT4), Na+/K+ pump α2, and superoxide dismutase 2 (SOD2) expressions were lower (P < 0.05) in m. deltoideus than in m. vastus lateralis, whereas deltoid had higher (P < 0.05) Na+/H+ exchanger 1 (NHE1) expression. As a result of training, Na+/K+ pump α2 isoform expression was elevated only in deltoideus muscle, while upregulation (P < 0.05) of the α1 and β1 subunits, phospholemman (FXYD1), NHE1, and superoxide dismutase 1 expression occurred exclusively in vastus lateralis muscle. The increased (P < 0.05) expression of MCT4 and SOD2 in deltoid muscle after HIS and vastus lateralis muscle after SOC were similar. In conclusion, arm musculature displays lower basal ROS, La−, K+ handling capability but higher Na+‐dependent H+ extrusion capacity than leg musculature. Training‐induced changes in the ion‐transporting and antioxidant proteins clearly differed between muscle groups.
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Affiliation(s)
- Magni Mohr
- Centre of Health Sciences, Faculty of Health Science, University of the Faroe Islands, Tórshavn, Faroe Islands.,Center for Health and Human Performance, Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, Sweden
| | - Tobias Schmidt Nielsen
- Department of Nutrition, Exercise and Sports, Section of Human Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Pál Weihe
- Centre of Health Sciences, Faculty of Health Science, University of the Faroe Islands, Tórshavn, Faroe Islands.,Department of Occupational Medicine and Public Health, The Faroese Hospital System, Tórshavn, Faroe Islands
| | - Jákup A Thomsen
- Centre of Health Sciences, Faculty of Health Science, University of the Faroe Islands, Tórshavn, Faroe Islands
| | - Giovanna Aquino
- Department of Movement Sciences and Wellness (DiSMEB), University "Parthenope", Naples, Italy.,CEINGE-Advanced Biotechnologies, Naples, Italy
| | - Peter Krustrup
- Department of Sports Science and Clinical Biomechanics, Faculty of Health Sciences, SDU Sport and Health Sciences Cluster (SHSC) University of Southern Denmark, Odense, Denmark.,Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Nikolai B Nordsborg
- Department of Nutrition, Exercise and Sports, Section of Human Physiology, University of Copenhagen, Copenhagen, Denmark
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San-Millán I, Brooks GA. Reexamining cancer metabolism: lactate production for carcinogenesis could be the purpose and explanation of the Warburg Effect. Carcinogenesis 2017; 38:119-133. [PMID: 27993896 PMCID: PMC5862360 DOI: 10.1093/carcin/bgw127] [Citation(s) in RCA: 239] [Impact Index Per Article: 34.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 12/08/2016] [Indexed: 12/15/2022] Open
Abstract
Herein, we use lessons learned in exercise physiology and metabolism to propose that augmented lactate production (‘lactagenesis’), initiated by gene mutations, is the reason and purpose of the Warburg Effect and that dysregulated lactate metabolism and signaling are the key elements in carcinogenesis. Lactate-producing (‘lactagenic’) cancer cells are characterized by increased aerobic glycolysis and excessive lactate formation, a phenomenon described by Otto Warburg 93 years ago, which still remains unexplained. After a hiatus of several decades, interest in lactate as a player in cancer has been renewed. In normal physiology, lactate, the obligatory product of glycolysis, is an important metabolic fuel energy source, the most important gluconeogenic precursor, and a signaling molecule (i.e. a ‘lactormone’) with major regulatory properties. In lactagenic cancers, oncogenes and tumor suppressor mutations behave in a highly orchestrated manner, apparently with the purpose of increasing glucose utilization for lactagenesis purposes and lactate exchange between, within and among cells. Five main steps are identified (i) increased glucose uptake, (ii) increased glycolytic enzyme expression and activity, (iii) decreased mitochondrial function, (iv) increased lactate production, accumulation and release and (v) upregulation of monocarboxylate transporters MTC1 and MCT4 for lactate exchange. Lactate is probably the only metabolic compound involved and necessary in all main sequela for carcinogenesis, specifically: angiogenesis, immune escape, cell migration, metastasis and self-sufficient metabolism. We hypothesize that lactagenesis for carcinogenesis is the explanation and purpose of the Warburg Effect. Accordingly, therapies to limit lactate exchange and signaling within and among cancer cells should be priorities for discovery.
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Affiliation(s)
- Iñigo San-Millán
- Department of Physical Medicine and Rehabilitation, University of Colorado School of Medicine, Aurora, CO 80045, USA.,Physiology Laboratory, CU Sports Medicine and Performance Center, Boulder, CO 80309, USA and
| | - George A Brooks
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
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Yeh HC, Ting IW, Tsai CW, Wu JY, Kuo CC. Serum lactate level and mortality in metformin-associated lactic acidosis requiring renal replacement therapy: a systematic review of case reports and case series. BMC Nephrol 2017; 18:229. [PMID: 28693440 PMCID: PMC5504722 DOI: 10.1186/s12882-017-0640-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 06/26/2017] [Indexed: 12/20/2022] Open
Abstract
Background The current practice concerning timing, mode, and dose of renal replacement therapy (RRT) in patients with metformin-associated lactic acidosis (MALA) with renal failure remains unknown. To investigate whether serum lactate level and prescription pattern of RRT are associated with mortality in patients with MALA requiring RRT. Methods We searched PubMed/Medline and EMBASE from inception to Sep 2014 and applied predetermined exclusion criteria. Case-level data including case’s demographics and clinical information related to MALA were abstracted. Multiple logistic regression modeling was used to examine the predictors of mortality. Results A total of 253 unique cases were identified with cumulative mortality of 17.2%. Eighty-seven percent of patients had acute kidney injury. Serum lactate level was significantly higher in non-survivors (median 22.5 mmol/L) than in survivors (17.0 mmol/L, p-value <0.01) and so did the median blood metformin concentrations (58.5 vs. 43.9 mg/L, p-value = 0.05). The survival advantage was not significantly different between the modalities of RRT. The adjusted odds ratio of mortality for every one mmol/L increase in serum lactate level was 1.09 (95% CI 1.02–1.17, p-value = 0.01). The dose-response curve indicated a lactate threshold greater than 20 mmol/L was significantly associated with mortality. Conclusions Our study suggests that predialysis level of serum lactate level is an important marker of mortality in MALA patients requiring RRT with a linear dose-response relationship. To better evaluate the optimal prescription of RRT in MALA, we recommend fostering an international consortium to support prospective research and large-scale standardized case collection. Electronic supplementary material The online version of this article (doi:10.1186/s12882-017-0640-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hung-Chieh Yeh
- Kidney Institute and Division of Nephrology, Department of Internal Medicine, China Medical University Hospital and College of Medicine, China Medical University, 2, Yude Rd., North Dist, Taichung City, 404, Taiwan
| | - I-Wen Ting
- Kidney Institute and Division of Nephrology, Department of Internal Medicine, China Medical University Hospital and College of Medicine, China Medical University, 2, Yude Rd., North Dist, Taichung City, 404, Taiwan
| | - Ching-Wei Tsai
- Kidney Institute and Division of Nephrology, Department of Internal Medicine, China Medical University Hospital and College of Medicine, China Medical University, 2, Yude Rd., North Dist, Taichung City, 404, Taiwan.,Big Data Center, China Medical University Hospital and College of Medicine, China Medical University, Taichung, Taiwan
| | - Jenn-Yu Wu
- Department of Internal Medicine, National Taiwan University Hospital Yun-Lin Branch, Yun-Lin, Taiwan
| | - Chin-Chi Kuo
- Kidney Institute and Division of Nephrology, Department of Internal Medicine, China Medical University Hospital and College of Medicine, China Medical University, 2, Yude Rd., North Dist, Taichung City, 404, Taiwan. .,Big Data Center, China Medical University Hospital and College of Medicine, China Medical University, Taichung, Taiwan.
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Paventi G, Pizzuto R, Passarella S. The occurrence of l-lactate dehydrogenase in the inner mitochondrial compartment of pig liver. Biochem Biophys Res Commun 2017; 489:255-261. [PMID: 28564593 DOI: 10.1016/j.bbrc.2017.05.154] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 05/26/2017] [Indexed: 10/19/2022]
Abstract
Although pig represents a model species in biomedical research including studies dealing with liver patho-physiology, some aspects of liver metabolism need to be addressed. In particular, whether and how pig mitochondria can metabolize l-lactate remains to be established. We show here that pig liver mitochondria (PLM) possess their own l-lactate dehydrogenase (mL-LDH). This was shown both via immunological analysis and by assaying photometrically the L-LDH reaction in solubilised PLM. The mL-LDH reaction shows hyperbolic dependence on the substrate concentration, it is inhibited by oxamate and proves to differ from the cytosolic activity (cL-LDH), as revealed by the difference found in both pH profiles and temperature dependence of m- and cL-LDH. Titration experiments with digitonin show that mL-LDH is restricted in mitochondrial inner compartment. In agreement with the above findings, three genes in Sus scrofa genome encoded for L-LDH subunits which are predicted to have mitochondrial localization, as investigated by Target P 1.1 and PredSL analysis.
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Affiliation(s)
- Gianluca Paventi
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, via De Sanctis, 86100 Campobasso, Italy.
| | - Roberto Pizzuto
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, via De Sanctis, 86100 Campobasso, Italy
| | - Salvatore Passarella
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, via De Sanctis, 86100 Campobasso, Italy; School of Medicine and Surgery, University of Bari, Hospital Policlinico, Piazza Giulio Cesare, 11, 70124 Bari, Italy
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Ražanskas P, Verikas A, Viberg PA, Olsson MC. Predicting physiological parameters in fatiguing bicycling exercises using muscle activation timing. Biomed Signal Process Control 2017. [DOI: 10.1016/j.bspc.2017.02.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Oliveira LF, de Salles Painelli V, Nemezio K, Gonçalves LS, Yamaguchi G, Saunders B, Gualano B, Artioli GG. Chronic lactate supplementation does not improve blood buffering capacity and repeated high-intensity exercise. Scand J Med Sci Sports 2016; 27:1231-1239. [DOI: 10.1111/sms.12792] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2016] [Indexed: 11/27/2022]
Affiliation(s)
- L. F. Oliveira
- Applied Physiology & Nutrition Research Group; University of Sao Paulo; São Paulo Brazil
| | - V. de Salles Painelli
- Applied Physiology & Nutrition Research Group; University of Sao Paulo; São Paulo Brazil
| | - K. Nemezio
- Applied Physiology & Nutrition Research Group; University of Sao Paulo; São Paulo Brazil
| | - L. S. Gonçalves
- Applied Physiology & Nutrition Research Group; University of Sao Paulo; São Paulo Brazil
| | - G. Yamaguchi
- Applied Physiology & Nutrition Research Group; University of Sao Paulo; São Paulo Brazil
| | - B. Saunders
- Applied Physiology & Nutrition Research Group; University of Sao Paulo; São Paulo Brazil
| | - B. Gualano
- Applied Physiology & Nutrition Research Group; University of Sao Paulo; São Paulo Brazil
| | - G. G. Artioli
- Applied Physiology & Nutrition Research Group; University of Sao Paulo; São Paulo Brazil
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36
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Lancha Junior AH, Painelli VDS, Saunders B, Artioli GG. Nutritional Strategies to Modulate Intracellular and Extracellular Buffering Capacity During High-Intensity Exercise. Sports Med 2016; 45 Suppl 1:S71-81. [PMID: 26553493 PMCID: PMC4672007 DOI: 10.1007/s40279-015-0397-5] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Intramuscular acidosis is a contributing factor to fatigue during high-intensity exercise. Many nutritional strategies aiming to increase intra- and extracellular buffering capacity have been investigated. Among these, supplementation of beta-alanine (~3–6.4 g/day for 4 weeks or longer), the rate-limiting factor to the intramuscular synthesis of carnosine (i.e. an intracellular buffer), has been shown to result in positive effects on exercise performance in which acidosis is a contributing factor to fatigue. Furthermore, sodium bicarbonate, sodium citrate and sodium/calcium lactate supplementation have been employed in an attempt to increase the extracellular buffering capacity. Although all attempts have increased blood bicarbonate concentrations, evidence indicates that sodium bicarbonate (0.3 g/kg body mass) is the most effective in improving high-intensity exercise performance. The evidence supporting the ergogenic effects of sodium citrate and lactate remain weak. These nutritional strategies are not without side effects, as gastrointestinal distress is often associated with the effective doses of sodium bicarbonate, sodium citrate and calcium lactate. Similarly, paresthesia (i.e. tingling sensation of the skin) is currently the only known side effect associated with beta-alanine supplementation, and it is caused by the acute elevation in plasma beta-alanine concentration after a single dose of beta-alanine. Finally, the co-supplementation of beta-alanine and sodium bicarbonate may result in additive ergogenic gains during high-intensity exercise, although studies are required to investigate this combination in a wide range of sports.
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Affiliation(s)
- Antonio Herbert Lancha Junior
- Laboratory of Applied Nutrition and Metabolism, School of Physical Education and Sport, University of São Paulo, Av. Mello de Moraes, 65 Butanta, São Paulo, SP, 05508-030, Brazil.
| | - Vitor de Salles Painelli
- Laboratory of Applied Nutrition and Metabolism, School of Physical Education and Sport, University of São Paulo, Av. Mello de Moraes, 65 Butanta, São Paulo, SP, 05508-030, Brazil
| | - Bryan Saunders
- Laboratory of Applied Nutrition and Metabolism, School of Physical Education and Sport, University of São Paulo, Av. Mello de Moraes, 65 Butanta, São Paulo, SP, 05508-030, Brazil
| | - Guilherme Giannini Artioli
- Laboratory of Applied Nutrition and Metabolism, School of Physical Education and Sport, University of São Paulo, Av. Mello de Moraes, 65 Butanta, São Paulo, SP, 05508-030, Brazil
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Oyarzún AP, Westermeier F, Pennanen C, López-Crisosto C, Parra V, Sotomayor-Flores C, Sánchez G, Pedrozo Z, Troncoso R, Lavandero S. FK866 compromises mitochondrial metabolism and adaptive stress responses in cultured cardiomyocytes. Biochem Pharmacol 2015; 98:92-101. [PMID: 26297909 DOI: 10.1016/j.bcp.2015.08.097] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 08/17/2015] [Indexed: 01/27/2023]
Abstract
AIM FK866 is an inhibitor of the NAD(+) synthesis rate-limiting enzyme nicotinamide phosphoribosyltransferase (NAMPT). Using FK866 to target NAD(+) synthesis has been proposed as a treatment for inflammatory diseases and cancer. However, use of FK866 may pose cardiovascular risks, as NAMPT expression is decreased in various cardiomyopathies, with low NAD(+) levels playing an important role in cardiovascular disease progression. In addition, low NAD(+) levels are associated with cardiovascular risk conditions such as aging, dyslipidemia, and type II diabetes mellitus. The aim of this work was to study the effects of FK866-induced NAD(+) depletion on mitochondrial metabolism and adaptive stress responses in cardiomyocytes. METHODS AND RESULTS FK866 was used to deplete NAD(+) levels in cultured rat cardiomyocytes. Cell viability, mitochondrial metabolism, and adaptive responses to insulin, norepinephrine, and H2O2 were assessed in cardiomyocytes. The drop in NAD(+) induced by FK866 decreased mitochondrial metabolism without changing cell viability. Insulin-stimulated Akt phosphorylation, glucose uptake, and H2O2-survival were compromised by FK866. Glycolytic gene transcription was increased, whereas cardiomyocyte hypertrophy induced by norepinephrine was prevented. Restoring NAD(+) levels via nicotinamide mononucleotide administration reestablished mitochondrial metabolism and adaptive stress responses. CONCLUSION This work shows that FK866 compromises mitochondrial metabolism and the adaptive response of cardiomyocytes to norepinephrine, H2O2, and insulin.
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Affiliation(s)
- Alejandra P Oyarzún
- Advanced Center for Chronic Disease (ACCDiS) and Center for Molecular Studies of the Cell (CEMC), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Francisco Westermeier
- Advanced Center for Chronic Disease (ACCDiS) and Center for Molecular Studies of the Cell (CEMC), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Christian Pennanen
- Advanced Center for Chronic Disease (ACCDiS) and Center for Molecular Studies of the Cell (CEMC), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Camila López-Crisosto
- Advanced Center for Chronic Disease (ACCDiS) and Center for Molecular Studies of the Cell (CEMC), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Valentina Parra
- Advanced Center for Chronic Disease (ACCDiS) and Center for Molecular Studies of the Cell (CEMC), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Cristian Sotomayor-Flores
- Advanced Center for Chronic Disease (ACCDiS) and Center for Molecular Studies of the Cell (CEMC), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Gina Sánchez
- Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Zully Pedrozo
- Advanced Center for Chronic Disease (ACCDiS) and Center for Molecular Studies of the Cell (CEMC), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile; Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Rodrigo Troncoso
- Advanced Center for Chronic Disease (ACCDiS) and Center for Molecular Studies of the Cell (CEMC), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile; Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile.
| | - Sergio Lavandero
- Advanced Center for Chronic Disease (ACCDiS) and Center for Molecular Studies of the Cell (CEMC), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile; Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile; Department of Internal Medicine (Cardiology Division), University of Texas Southwestern Medical Center, Dallas, Texas, USA.
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Glenn TC, Martin NA, McArthur DL, Hovda DA, Vespa P, Johnson ML, Horning MA, Brooks GA. Endogenous Nutritive Support after Traumatic Brain Injury: Peripheral Lactate Production for Glucose Supply via Gluconeogenesis. J Neurotrauma 2015; 32:811-9. [PMID: 25279664 PMCID: PMC4530391 DOI: 10.1089/neu.2014.3482] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
We evaluated the hypothesis that nutritive needs of injured brains are supported by large and coordinated increases in lactate shuttling throughout the body. To that end, we used dual isotope tracer ([6,6-(2)H2]glucose, i.e., D2-glucose, and [3-(13)C]lactate) techniques involving central venous tracer infusion along with cerebral (arterial [art] and jugular bulb [JB]) blood sampling. Patients with traumatic brain injury (TBI) who had nonpenetrating head injuries (n=12, all male) were entered into the study after consent of patients' legal representatives. Written and informed consent was obtained from healthy controls (n=6, including one female). As in previous investigations, the cerebral metabolic rate (CMR) for glucose was suppressed after TBI. Near normal arterial glucose and lactate levels in patients studied 5.7±2.2 days (range of days 2-10) post-injury, however, belied a 71% increase in systemic lactate production, compared with control, that was largely cleared by greater (hepatic+renal) glucose production. After TBI, gluconeogenesis from lactate clearance accounted for 67.1% of glucose rate of appearance (Ra), which was compared with 15.2% in healthy controls. We conclude that elevations in blood glucose concentration after TBI result from a massive mobilization of lactate from corporeal glycogen reserves. This previously unrecognized mobilization of lactate subserves hepatic and renal gluconeogenesis. As such, a lactate shuttle mechanism indirectly makes substrate available for the body and its essential organs, including the brain, after trauma. In addition, when elevations in arterial lactate concentration occur after TBI, lactate shuttling may provide substrate directly to vital organs of the body, including the injured brain.
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Affiliation(s)
- Thomas C. Glenn
- University of California, Los Angeles, Cerebral Blood Flow Laboratory, Los Angeles, California
- Division of Neurosurgery, University of California, Los Angeles (UCLA), UCLA Center for Health Sciences, Los Angeles, California
| | - Neil A. Martin
- University of California, Los Angeles, Cerebral Blood Flow Laboratory, Los Angeles, California
- Division of Neurosurgery, University of California, Los Angeles (UCLA), UCLA Center for Health Sciences, Los Angeles, California
| | - David L. McArthur
- University of California, Los Angeles, Cerebral Blood Flow Laboratory, Los Angeles, California
| | - David A. Hovda
- University of California, Los Angeles, Cerebral Blood Flow Laboratory, Los Angeles, California
| | - Paul Vespa
- University of California, Los Angeles, Cerebral Blood Flow Laboratory, Los Angeles, California
| | - Matthew L. Johnson
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California
| | - Michael A. Horning
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California
| | - George A. Brooks
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California
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Kane DA. Lactate oxidation at the mitochondria: a lactate-malate-aspartate shuttle at work. Front Neurosci 2014; 8:366. [PMID: 25505376 PMCID: PMC4243568 DOI: 10.3389/fnins.2014.00366] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 10/25/2014] [Indexed: 11/30/2022] Open
Abstract
Lactate, the conjugate base of lactic acid occurring in aqueous biological fluids, has been derided as a “dead-end” waste product of anaerobic metabolism. Catalyzed by the near-equilibrium enzyme lactate dehydrogenase (LDH), the reduction of pyruvate to lactate is thought to serve to regenerate the NAD+ necessary for continued glycolytic flux. Reaction kinetics for LDH imply that lactate oxidation is rarely favored in the tissues of its own production. However, a substantial body of research directly contradicts any notion that LDH invariably operates unidirectionally in vivo. In the current Perspective, a model is forwarded in which the continuous formation and oxidation of lactate serves as a mitochondrial electron shuttle, whereby lactate generated in the cytosol of the cell is oxidized at the mitochondria of the same cell. From this perspective, an intracellular lactate shuttle operates much like the malate-aspartate shuttle (MAS); it is also proposed that the two shuttles are necessarily interconnected in a lactate-MAS. Among the requisite features of such a model, significant compartmentalization of LDH, much like the creatine kinase of the phosphocreatine shuttle, would facilitate net cellular lactate oxidation in a variety of cell types.
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Affiliation(s)
- Daniel A Kane
- Department of Human Kinetics, St. Francis Xavier University Antigonish, NS, Canada
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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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DeBalsi KL, Wong KE, Koves TR, Slentz DH, Seiler SE, Wittmann AH, Ilkayeva OR, Stevens RD, Perry CGR, Lark DS, Hui ST, Szweda L, Neufer PD, Muoio DM. Targeted metabolomics connects thioredoxin-interacting protein (TXNIP) to mitochondrial fuel selection and regulation of specific oxidoreductase enzymes in skeletal muscle. J Biol Chem 2014; 289:8106-20. [PMID: 24482226 DOI: 10.1074/jbc.m113.511535] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Thioredoxin-interacting protein (TXNIP) is an α-arrestin family member involved in redox sensing and metabolic control. Growing evidence links TXNIP to mitochondrial function, but the molecular nature of this relationship has remained poorly defined. Herein, we employed targeted metabolomics and comprehensive bioenergetic analyses to evaluate oxidative metabolism and respiratory kinetics in mouse models of total body (TKO) and skeletal muscle-specific (TXNIP(SKM-/-)) Txnip deficiency. Compared with littermate controls, both TKO and TXNIP(SKM-/-) mice had reduced exercise tolerance in association with muscle-specific impairments in substrate oxidation. Oxidative insufficiencies in TXNIP null muscles were not due to perturbations in mitochondrial mass, the electron transport chain, or emission of reactive oxygen species. Instead, metabolic profiling analyses led to the discovery that TXNIP deficiency causes marked deficits in enzymes required for catabolism of branched chain amino acids, ketones, and lactate, along with more modest reductions in enzymes of β-oxidation and the tricarboxylic acid cycle. The decrements in enzyme activity were accompanied by comparable deficits in protein abundance without changes in mRNA expression, implying dysregulation of protein synthesis or stability. Considering that TXNIP expression increases in response to starvation, diabetes, and exercise, these findings point to a novel role for TXNIP in coordinating mitochondrial fuel switching in response to nutrient availability.
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Adeva M, González-Lucán M, Seco M, Donapetry C. Enzymes involved in l-lactate metabolism in humans. Mitochondrion 2013; 13:615-29. [DOI: 10.1016/j.mito.2013.08.011] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 07/29/2013] [Accepted: 08/30/2013] [Indexed: 12/20/2022]
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Jacobs RA, Flück D, Bonne TC, Bürgi S, Christensen PM, Toigo M, Lundby C. Improvements in exercise performance with high-intensity interval training coincide with an increase in skeletal muscle mitochondrial content and function. J Appl Physiol (1985) 2013; 115:785-93. [DOI: 10.1152/japplphysiol.00445.2013] [Citation(s) in RCA: 168] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Six sessions of high-intensity interval training (HIT) are sufficient to improve exercise capacity. The mechanisms explaining such improvements are unclear. Accordingly, the aim of this study was to perform a comprehensive evaluation of physiologically relevant adaptations occurring after six sessions of HIT to determine the mechanisms explaining improvements in exercise performance. Sixteen untrained (43 ± 6 ml·kg−1·min−1) subjects completed six sessions of repeated ( 8 – 12 ) 60 s intervals of high-intensity cycling (100% peak power output elicited during incremental maximal exercise test) intermixed with 75 s of recovery cycling at a low intensity (30 W) over a 2-wk period. Potential training-induced alterations in skeletal muscle respiratory capacity, mitochondrial content, skeletal muscle oxygenation, cardiac capacity, blood volumes, and peripheral fatigue resistance were all assessed prior to and again following training. Maximal measures of oxygen uptake (V̇o2peak; ∼8%; P = 0.026) and cycling time to complete a set amount of work (∼5%; P = 0.008) improved. Skeletal muscle respiratory capacities increased, most likely as a result of an expansion of skeletal muscle mitochondria (∼20%, P = 0.026), as assessed by cytochrome c oxidase activity. Skeletal muscle deoxygenation also increased while maximal cardiac output, total hemoglobin, plasma volume, total blood volume, and relative measures of peripheral fatigue resistance were all unaltered with training. These results suggest that increases in mitochondrial content following six HIT sessions may facilitate improvements in respiratory capacity and oxygen extraction, and ultimately are responsible for the improvements in maximal whole body exercise capacity and endurance performance in previously untrained individuals.
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Affiliation(s)
- Robert Acton Jacobs
- Zurich Center for Integrative Human Physiology (ZIHP), Zurich, Switzerland
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland:
| | - Daniela Flück
- Zurich Center for Integrative Human Physiology (ZIHP), Zurich, Switzerland
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Thomas Christian Bonne
- Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark; and
| | - Simon Bürgi
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | | | - Marco Toigo
- Zurich Center for Integrative Human Physiology (ZIHP), Zurich, Switzerland
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Exercise Physiology, Institute of Human Movement Sciences, ETH Zurich, Zurich, Switzerland
| | - Carsten Lundby
- Zurich Center for Integrative Human Physiology (ZIHP), Zurich, Switzerland
- Institute of Physiology, University of Zurich, Zurich, Switzerland
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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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Emhoff CAW, Messonnier LA, Horning MA, Fattor JA, Carlson TJ, Brooks GA. Direct and indirect lactate oxidation in trained and untrained men. J Appl Physiol (1985) 2013; 115:829-38. [PMID: 23788576 DOI: 10.1152/japplphysiol.00538.2013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lactate has been shown to be an important oxidative fuel. We aimed to quantify the total lactate oxidation rate (Rox) and its direct vs. indirect (glucose that is gluconeogenically derived from lactate and subsequently oxidized) components (mg·kg(-1)·min(-1)) during rest and exercise in humans. We also investigated the effects of endurance training, exercise intensity, and blood lactate concentration ([lactate]b) on direct and indirect lactate oxidation. Six untrained (UT) and six trained (T) men completed 60 min of constant load exercise at power outputs corresponding to their lactate threshold (LT). T subjects completed two additional 60-min sessions of constant load exercise at 10% below the LT workload (LT-10%), one of which included a lactate clamp (LC; LT-10%+LC). Rox was higher at LT in T [22.7 ± 2.9, 75% peak oxygen consumption (Vo2peak)] compared with UT (13.4 ± 2.5, 68% Vo2peak, P < 0.05). Increasing [lactate]b (LT-10%+LC, 67% Vo2peak) significantly increased lactate Rox (27.9 ± 3.0) compared with its corresponding LT-10% control (15.9 ± 2.2, P < 0.05). Direct and indirect Rox increased significantly from rest to exercise, and their relative partitioning remained constant in all trials but differed between T and UT: direct oxidation comprised 75% of total lactate oxidation in UT and 90% in T, suggesting the presence of training-induced adaptations. Partitioning of total carbohydrate (CHO) use showed that subjects derived one-third of CHO energy from blood lactate, and exogenous lactate infusion increased lactate oxidation significantly, causing a glycogen-sparing effect in exercising muscle.
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Affiliation(s)
- Chi-An W Emhoff
- Department of Integrative Biology, University of California, Berkeley, California
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