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Pedersen MGB, Rittig N, Bangshaab M, Berg-Hansen K, Gopalasingam N, Gormsen LC, Søndergaard E, Møller N. Effects of exogenous lactate on lipid, protein, and glucose metabolism-a randomized crossover trial in healthy males. Am J Physiol Endocrinol Metab 2024; 326:E443-E453. [PMID: 38324259 PMCID: PMC11193511 DOI: 10.1152/ajpendo.00301.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 01/18/2024] [Accepted: 02/01/2024] [Indexed: 02/08/2024]
Abstract
Lactate may inhibit lipolysis and thus enhance insulin sensitivity, but there is a lack of metabolic human studies. This study aimed to determine how hyperlactatemia affects lipolysis, glucose- and protein metabolism, and insulin sensitivity in healthy men. In a single-blind, randomized, crossover design, eight healthy men were studied after an overnight fast on two occasions: 1) during a sodium-lactate infusion (LAC) and 2) during a sodium-matched NaCl infusion (CTR). Both days consisted of a 3-h postabsorptive period followed by a 3-h hyperinsulinemic-euglycemic clamp (HEC). Lipolysis rate, endogenous glucose production (EGP), and delta glucose rate of disappearance (ΔRdglu) were evaluated using [9,10-3H]palmitate and [3-3H]glucose tracers. In addition, whole body- and forearm protein metabolism was assessed using [15N]phenylalanine, [2H4]tyrosine, [15N]tyrosine, and [13C]urea tracers. In the postabsorptive period, plasma lactate increased to 2.7 ± 0.5 mmol/L during LAC vs. 0.6 ± 0.3 mmol/L during CTR (P < 0.001). In the postabsorptive period, palmitate flux was 30% lower during LAC compared with CTR (84 ± 32 µmol/min vs. 120 ± 35 µmol/min, P = 0.003). During the HEC, palmitate flux was suppressed similarly during both interventions (P = 0.7). EGP, ΔRdglu, and M value were similar during LAC and CTR. During HEC, LAC increased whole body phenylalanine flux (P = 0.02) and protein synthesis (P = 0.03) compared with CTR; LAC did not affect forearm protein metabolism compared with CTR. Lactate infusion inhibited lipolysis by 30% under postabsorptive conditions but did not affect glucose metabolism or improve insulin sensitivity. In addition, whole body phenylalanine flux was increased. Clinical trial registrations: NCT04710875.NEW & NOTEWORTHY Lactate is a decisive intermediary metabolite, serving as an energy substrate and a signaling molecule. The present study examines the effects of lactate on substrate metabolism and insulin sensitivity in healthy males. Hyperlactatemia reduces lipolysis by 30% without affecting insulin sensitivity and glucose metabolism. In addition, hyperlactatemia increases whole body amino acid turnover rate.
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Affiliation(s)
- Mette G B Pedersen
- Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark
- Medical Research Laboratory, Aarhus University, Aarhus, Denmark
| | - Nikolaj Rittig
- Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark
- Medical Research Laboratory, Aarhus University, Aarhus, Denmark
| | - Maj Bangshaab
- Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark
- Medical Research Laboratory, Aarhus University, Aarhus, Denmark
| | | | | | - Lars C Gormsen
- Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark
| | - Esben Søndergaard
- Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark
| | - Niels Møller
- Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark
- Medical Research Laboratory, Aarhus University, Aarhus, Denmark
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2
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Colucci ACM, Tassinari ID, Loss EDS, de Fraga LS. History and Function of the Lactate Receptor GPR81/HCAR1 in the Brain: A Putative Therapeutic Target for the Treatment of Cerebral Ischemia. Neuroscience 2023; 526:144-163. [PMID: 37391123 DOI: 10.1016/j.neuroscience.2023.06.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 06/21/2023] [Accepted: 06/24/2023] [Indexed: 07/02/2023]
Abstract
GPR81 is a G-protein coupled receptor (GPCR) discovered in 2001, but deorphanized only 7 years later, when its affinity for lactate as an endogenous ligand was demonstrated. More recently, GPR81 expression and distribution in the brain were also confirmed and the function of lactate as a volume transmitter has been suggested since then. These findings shed light on a new function of lactate acting as a signaling molecule in the central nervous system, in addition to its well-known role as a metabolic fuel for neurons. GPR81 seems to act as a metabolic sensor, coupling energy metabolism, synaptic activity, and blood flow. Activation of this receptor leads to Gi-mediated downregulation of adenylyl cyclase and subsequent reduction in cAMP levels, regulating several downstream pathways. Recent studies have also suggested the potential role of lactate as a neuroprotective agent, mainly under brain ischemic conditions. This effect is usually attributed to the metabolic role of lactate, but the underlying mechanisms need further investigation and could be related to lactate signaling via GPR81. The activation of GPR81 showed promising results for neuroprotection: it modulates many processes involved in the pathophysiology of ischemia. In this review, we summarize the history of GPR81, starting with its deorphanization; then, we discuss GPR81 expression and distribution, signaling transduction cascades, and neuroprotective roles. Lastly, we propose GPR81 as a potential target for the treatment of cerebral ischemia.
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Affiliation(s)
- Anna Clara Machado Colucci
- Laboratório de Neurobiologia e Metabolismo (NeuroMet), Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde (ICBS), Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600, lab. 660, Porto Alegre, Brazil; Programa de Pós-Graduação em Ciências Biológicas: Fisiologia, Instituto de Ciências Básicas da Saúde (ICBS), Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600, Porto Alegre, Brazil; Centro de Pesquisa Experimental, Hospital de Clínicas de Porto Alegre (HCPA), Rua Ramiro Barcelos, 2350, Porto Alegre, Brazil
| | - Isadora D'Ávila Tassinari
- Laboratório de Neurobiologia e Metabolismo (NeuroMet), Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde (ICBS), Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600, lab. 660, Porto Alegre, Brazil; Programa de Pós-Graduação em Ciências Biológicas: Fisiologia, Instituto de Ciências Básicas da Saúde (ICBS), Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600, Porto Alegre, Brazil; Centro de Pesquisa Experimental, Hospital de Clínicas de Porto Alegre (HCPA), Rua Ramiro Barcelos, 2350, Porto Alegre, Brazil
| | - Eloísa da Silveira Loss
- Laboratório de Endocrinologia Experimental (LABENEX), Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde (ICBS), Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600, lab. 660, Porto Alegre, Brazil; Programa de Pós-Graduação em Ciências Biológicas: Fisiologia, Instituto de Ciências Básicas da Saúde (ICBS), Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600, Porto Alegre, Brazil
| | - Luciano Stürmer de Fraga
- Laboratório de Neurobiologia e Metabolismo (NeuroMet), Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde (ICBS), Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600, lab. 660, Porto Alegre, Brazil; Programa de Pós-Graduação em Ciências Biológicas: Fisiologia, Instituto de Ciências Básicas da Saúde (ICBS), Universidade Federal do Rio Grande do Sul (UFRGS), Rua Ramiro Barcelos, 2600, Porto Alegre, Brazil; Centro de Pesquisa Experimental, Hospital de Clínicas de Porto Alegre (HCPA), Rua Ramiro Barcelos, 2350, Porto Alegre, Brazil.
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Emhoff CAW, Messonnier LA. Concepts of Lactate Metabolic Clearance Rate and Lactate Clamp for Metabolic Inquiry: A Mini-Review. Nutrients 2023; 15:3213. [PMID: 37513631 PMCID: PMC10385598 DOI: 10.3390/nu15143213] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/16/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023] Open
Abstract
Lactate is known to play a central role in the link between glycolytic and mitochondrial oxidative metabolism, as well as to serve as a primary gluconeogenic precursor. Blood lactate concentration is sensitive to the metabolic state of tissues and organs as lactate rates of appearance and disposal/disappearance in the circulation rise and fall in response to physical exercise and other metabolic disturbances. The highest lactate flux rates have been measured during moderate intensity exercise in endurance-trained individuals who exhibit muscular and metabolic adaptations lending to superior oxidative capacity. In contrast, a diminished ability to utilize lactate is associated with poor metabolic fitness. Given these widespread implications in exercise performance and health, we discuss the concept of lactate metabolic clearance rate, which increases at the onset of exercise and, unlike flux rates, reaches a peak just below the power output associated with the maximal lactate steady state. The metabolic clearance rate is determined by both disposal rate and blood concentration, two parameters that are mutually interdependent and thus difficult to parse during steady state exercise studies. We review the evolution of the in vivo lactate clamp methodology to control blood lactate concentration and discuss its application in the investigation of whole-body lactate disposal capacities. In conclusion, we assert that the lactate clamp is a useful research methodology for examining lactate flux, in particular the factors that drive metabolic clearance rate.
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Affiliation(s)
- Chi-An W Emhoff
- Department of Kinesiology, Saint Mary's College of California, Moraga, CA 94575, USA
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Savoie Mont Blanc, F-73000 Chambéry, France
| | - Laurent A Messonnier
- Laboratoire Interuniversitaire de Biologie de la Motricité, Université Savoie Mont Blanc, F-73000 Chambéry, France
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4
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Pedersen MGB, Søndergaard E, Nielsen CB, Johannsen M, Gormsen LC, Møller N, Jessen N, Rittig N. Oral lactate slows gastric emptying and suppresses appetite in young males. Clin Nutr 2022; 41:517-525. [PMID: 35016146 DOI: 10.1016/j.clnu.2021.12.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 12/09/2021] [Accepted: 12/20/2021] [Indexed: 12/26/2022]
Abstract
BACKGROUND Lactate serves as an alternative energy fuel but is also an important signaling metabolite. We aimed to investigate whether oral lactate administration affects appetite-regulating hormones, slows gastric emptying rate, and dampens appetite. METHODS Ten healthy male volunteers were investigated on two separate occasions: 1) following oral ingestion of D/L-Na-lactate and 2) following oral ingestion of isotonic iso-voluminous NaCl and intravenous iso-lactemic D/L-Na-lactate infusions. Appetite was evaluated by questionnaires and ad libitum meal tests were performed at the end of each study day. Gastric emptying rate was evaluated using the acetaminophen test. RESULTS Plasma concentrations of growth differential factor 15 (GDF15, primary outcome) increased following oral and iv administration of lactate (p < 0.001) with no detectable difference between interventions (p = 0.15). Oral lactate administration lowered plasma concentrations of acylated ghrelin (p = 0.02) and elevated glucagon like peptide-1 (GLP-1, p = 0.045), insulin (p < 0.001), and glucagon (p < 0.001) compared with iv administration. Oral lactate administration slowed gastric emptying (p < 0.001), increased the feeling of being "full" (p = 0.008) and lowered the "anticipated future food intake" (p = 0.007) compared with iv administration. Food intake during the ad libitum meal test did not differ between the two study days. CONCLUSION Oral lactate administration has a direct effect on the upper gastrointestinal tract, affecting gut hormone secretion, motility and appetite sensations which cannot be mediated through lactate in the systemic circulation alone. These data suggest that compounds rich in lactate may be useful in the treatment of metabolic disease. CLINICAL TRIAL REGISTRY NUMBER NCT0429981, https://clinicaltrials.gov/ct2/show/NCT04299815.
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Affiliation(s)
- Mette Glavind Bülow Pedersen
- Medical/Steno Aarhus Research Laboratory, Aarhus University, Aarhus University Hospital, Palle Juul-Jensens Blvd 165, 8200 Aarhus N, Denmark; Steno Diabetes Center Aarhus, Aarhus University Hospital, Hedeager 3, 8200 Aarhus N, Denmark.
| | - Esben Søndergaard
- Steno Diabetes Center Aarhus, Aarhus University Hospital, Hedeager 3, 8200 Aarhus N, Denmark; Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Palle Juul-Jensens Boulevard 165, 8200 Aarhus N, Denmark
| | - Camilla Bak Nielsen
- Department of Forensic Medicine, Aarhus University, Palle Juul-Jensens Boulevard 43, 8200 Aarhus N, Denmark
| | - Mogens Johannsen
- Department of Forensic Medicine, Aarhus University, Palle Juul-Jensens Boulevard 43, 8200 Aarhus N, Denmark
| | - Lars Christian Gormsen
- Department of Nuclear Medicine and PET-Centre, Aarhus University Hospital, Palle Juul-Jensens Blvd. 165, 8200 Aarhus N, Denmark
| | - Niels Møller
- Medical/Steno Aarhus Research Laboratory, Aarhus University, Aarhus University Hospital, Palle Juul-Jensens Blvd 165, 8200 Aarhus N, Denmark; Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Palle Juul-Jensens Boulevard 165, 8200 Aarhus N, Denmark
| | - Niels Jessen
- Steno Diabetes Center Aarhus, Aarhus University Hospital, Hedeager 3, 8200 Aarhus N, Denmark
| | - Nikolaj Rittig
- Steno Diabetes Center Aarhus, Aarhus University Hospital, Hedeager 3, 8200 Aarhus N, Denmark; Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Palle Juul-Jensens Boulevard 165, 8200 Aarhus N, Denmark
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5
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Chen S, Zhou L, Sun J, Qu Y, Chen M. The Role of cAMP-PKA Pathway in Lactate-Induced Intramuscular Triglyceride Accumulation and Mitochondria Content Increase in Mice. Front Physiol 2021; 12:709135. [PMID: 34588991 PMCID: PMC8473783 DOI: 10.3389/fphys.2021.709135] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 08/17/2021] [Indexed: 11/13/2022] Open
Abstract
The glycolytic product of exercise, lactate, has long been recognized to promote lipid accumulation by activation of G-protein-coupled receptor 81 (GPR81) and inhibition of the cyclic adenosine monophosphate-protein kinase A (cAMP -PKA) pathway in adipose tissue. Whether lactate causes a similar process in skeletal muscle is unclear. Lactate might also improve mitochondria content in skeletal muscle; however, the mechanism is not clarified either. In this study, using intramuscular injection of lactate to the gastrocnemius and intraperitoneal injection of forskolin (activator of cAMP-PKA pathway), we identified the role of the cAMP-PKA pathway in lactate-induced intramuscular triglyceride accumulation and mitochondrial content increase. The intramuscular triglyceride level in the gastrocnemius increased after 5weeks of lactate injection (p<0.05), and this effect was blocked by forskolin injection (p<0.05). Corresponding expression level changes of GPR81, P-PKA/PKA, P-CREB/cAMP-response element binding protein (CREB), and proteins related to lipid metabolism suggest that lactate could induce intramuscular triglyceride accumulation partly through the inhibition of the cAMP-PKA pathway. Meanwhile, the intramuscular expression of citrate synthase (CS) and the activity of CS increased after 5weeks of lactate injection (p<0.05), but the change of CS expression was not blocked by forskolin injection, suggesting other mechanisms might exist. Consequently, exploration for other potential mechanisms that might contribute to the lactate-induced mitochondria content increase was conducted. We found an increase in the contents of lactate-related metabolites in skeletal muscle mitochondria after acute lactate injection (the p-value of each analysis is less than 0.05). LHDA was also validated to exist in mitochondria in this study. These results provide a possibility for metabolism-related mechanisms of lactate-induced mitochondria content increase. Future study is needed to validate this hypothesis. In conclusion, lactate-induced intramuscular triglyceride accumulation is achieved by inhibition of lipolysis, and this process is regulated by the cAMP-PKA pathway. Promoted lipogenesis also contributes to lactate-induced triglyceride accumulation, and this process might also be regulated by the cAMP-PKA pathway. Lactate injection might increase mitochondria content and cAMP-PKA pathway might have a limited contribution, while other metabolism-related mechanisms might play a prominent role.
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Affiliation(s)
- Siyu Chen
- Institute of Sports Science, Sichuan University, Chengdu, China
| | - Lei Zhou
- Institute of Sports Science, Sichuan University, Chengdu, China
| | - Jingquan Sun
- Institute of Sports Science, Sichuan University, Chengdu, China.,School of Physical Education and Sports, Sichuan University, Chengdu, China
| | - Yaqian Qu
- Institute of Sports Science, Sichuan University, Chengdu, China
| | - Min Chen
- Institute of Sports Science, Sichuan University, Chengdu, China
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6
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Templeman JR, Trevizan L, Ma DWL, Shoveller AK. Fatty Acid Profiles of Serum Lipid Fractions Change Minimally in Sled Dogs Before and After Short Bouts of Exercise. Front Vet Sci 2021; 8:704770. [PMID: 34497842 PMCID: PMC8421022 DOI: 10.3389/fvets.2021.704770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 08/03/2021] [Indexed: 11/23/2022] Open
Abstract
Although emerging data suggests a greater influence of gluconeogenic precursors, endurance sled dogs have long appeared to rely heavily on fatty acid oxidation for sustained energy production. However, much of the research investigating lipid utilization during exercise in sled dogs has been carried out with dogs subjected to extended bouts of endurance exercise. Less is known about changes in fatty acid composition in endurance training sled dogs subjected to short bouts of exercise, and fewer data define how fatty acid composition may change in distinct lipid fractions. As such, the study objective was to assess whether short bouts of submaximal exercise would affect fatty acid profiles of serum lipid fractions in endurance training sled dogs. Fifteen privately-owned Siberian huskies were used (8 females: 4 intact, 4 spayed; 7 males: 2 intact, 5 neutered), with an average age of 4.6 ± 2.5 years and body weight of 24.8 ± 4.2 kg. Throughout the diet acclimation and remainder of the study, all dogs were fed a dry extruded diet that met or exceeded all AAFCO nutrient recommendations. Dogs were weighed weekly and fed to maintain baseline body weight. A 12-week exercise regimen was designed to incorporate weekly increases in running distance, but weather played a role in setting the daily distance. On weeks 2, 5, and 11, an exercise challenge was implemented whereby dogs would run 4 km at 15 km/h in teams of 4. Pre- and post-exercise blood samples were taken, and gas chromatography was used to evaluate fatty acid profiles of all identified serum lipid fractions (cholesterol ester, diacylglycerol, free fatty acid, phospholipids, triglyceride). Data were analyzed using PROC MIXED of SAS, with dog as a random effect and week and sampling time point as fixed effects. Composition of oleic (18:1n9), linoleic (18:2n6), and alpha-linolenic (18:3n3) acids in the free fatty acid fraction decreased by ~9, 10, and 60%, respectively, following exercise (P ≤ 0.05). The results presented herein suggest that aside from a degree of depletion of these 18-carbon unsaturated fatty acids, short bouts of submaximal exercise do not induce considerable changes to sled dog fatty acid profiles.
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Affiliation(s)
- James R Templeman
- Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
| | - Luciano Trevizan
- Department of Animal Science, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - David W L Ma
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Anna K Shoveller
- Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
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Abstract
After almost a century of misunderstanding, it is time to appreciate that lactate shuttling is an important feature of energy flux and metabolic regulation that involves a complex series of metabolic, neuroendocrine, cardiovascular, and cardiac events in vivo. Cell–cell and intracellular lactate shuttles in the heart and between the heart and other tissues fulfill essential purposes of energy substrate production and distribution as well as cell signaling under fully aerobic conditions. Recognition of lactate shuttling came first in studies of physical exercise where the roles of driver (producer) and recipient (consumer) cells and tissues were obvious. One powerful example of cell–cell lactate shuttling was the exchange of carbohydrate energy in the form of lactate between working limb skeletal muscle and the heart. The exchange of mass represented a conservation of mass that required the integration of neuroendocrine, autoregulatory, and cardiovascular systems. Now, with greater scrutiny and recognition of the effect of the cardiac cycle on myocardial blood flow, there brings an appreciation that metabolic fluxes must accommodate to pressure-flow realities within an organ in which they occur. Therefore, the presence of an intra-cardiac lactate shuttle is posited to explain how cardiac mechanics and metabolism are synchronized. Specifically, interruption of blood flow during the isotonic phase of systole is supported by glycolysis and subsequent return of blood flow during diastole allows for recovery sustained by oxidative metabolism.
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Affiliation(s)
- George A Brooks
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, Berkeley, CA, United States
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8
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Brooks GA, Arevalo JA, Osmond AD, Leija RG, Curl CC, Tovar AP. Lactate in contemporary biology: a phoenix risen. J Physiol 2021; 600:1229-1251. [PMID: 33566386 PMCID: PMC9188361 DOI: 10.1113/jp280955] [Citation(s) in RCA: 90] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/21/2021] [Indexed: 12/13/2022] Open
Abstract
After a century, it's time to turn the page on understanding of lactate metabolism and appreciate that lactate shuttling is an important component of intermediary metabolism in vivo. Cell‐cell and intracellular lactate shuttles fulfil purposes of energy substrate production and distribution, as well as cell signalling under fully aerobic conditions. Recognition of lactate shuttling came first in studies of physical exercise where the roles of driver (producer) and recipient (consumer) cells and tissues were obvious. Moreover, the presence of lactate shuttling as part of postprandial glucose disposal and satiety signalling has been recognized. Mitochondrial respiration creates the physiological sink for lactate disposal in vivo. Repeated lactate exposure from regular exercise results in adaptive processes such as mitochondrial biogenesis and other healthful circulatory and neurological characteristics such as improved physical work capacity, metabolic flexibility, learning, and memory. The importance of lactate and lactate shuttling in healthful living is further emphasized when lactate signalling and shuttling are dysregulated as occurs in particular illnesses and injuries. Like a phoenix, lactate has risen to major importance in 21st century biology.
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Affiliation(s)
- George A Brooks
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - Jose A Arevalo
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - Adam D Osmond
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - Robert G Leija
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - Casey C Curl
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - Ashley P Tovar
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, CA, USA
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9
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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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10
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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: 281] [Impact Index Per Article: 70.3] [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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11
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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: 641] [Impact Index Per Article: 106.8] [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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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: 209] [Impact Index Per Article: 34.8] [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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Overexpressing cell systems are a competitive option to primary adipocytes when predicting in vivo potency of dual GPR81/GPR109A agonists. Eur J Pharm Sci 2017; 114:155-165. [PMID: 29180298 DOI: 10.1016/j.ejps.2017.11.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 11/01/2017] [Accepted: 11/23/2017] [Indexed: 02/06/2023]
Abstract
Mathematical models predicting in vivo pharmacodynamic effects from in vitro data can accelerate drug discovery, and reduce costs and animal use. However, data integration and modeling is non-trivial when more than one drug-target receptor is involved in the biological response. We modeled the inhibition of non-esterified fatty acid release by dual G-protein-coupled receptor 81/109A (GPR81/GPR109A) agonists in vivo in the rat, to estimate the in vivo EC50 values for 12 different compounds. We subsequently predicted those potency estimates using EC50 values obtained from concentration-response data in isolated primary adipocytes and cell systems overexpressing GPR81 or GPR109A in vitro. A simple linear regression model based on data from primary adipocytes predicted the in vivo EC50 better than simple linear regression models based on in vitro data from either of the cell systems. Three models combining the data from the overexpressing cell systems were also evaluated: two piecewise linear models defining logical OR- and AND-circuits, and a multivariate linear regression model. All three models performed better than the simple linear regression model based on data from primary adipocytes. The OR-model was favored since it is likely that activation of either GPR81 or GPR109A is sufficient to deactivate the cAMP pathway, and thereby inhibit non-esterified fatty acid release. The OR-model was also able to predict the in vivo selectivity between the two receptors. Finally, the OR-model was used to predict the in vivo potency of 1651 new compounds. This work suggests that data from the overexpressing cell systems are sufficient to predict in vivo potency of GPR81/GPR109A agonists, an approach contributing to faster and leaner drug discovery.
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Nalbandian M, Takeda M. Lactate as a Signaling Molecule That Regulates Exercise-Induced Adaptations. BIOLOGY 2016; 5:E38. [PMID: 27740597 PMCID: PMC5192418 DOI: 10.3390/biology5040038] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 09/28/2016] [Indexed: 12/21/2022]
Abstract
Lactate (or its protonated form: lactic acid) has been studied by many exercise scientists. The lactate paradigm has been in constant change since lactate was first discovered in 1780. For many years, it was unfairly seen as primarily responsible for muscular fatigue during exercise and a waste product of glycolysis. The status of lactate has slowly changed to an energy source, and in the last two decades new evidence suggests that lactate may play a much bigger role than was previously believed: many adaptations to exercise may be mediated in some way by lactate. The mechanisms behind these adaptations are yet to be understood. The aim of this review is to present the state of lactate science, focusing on how this molecule may mediate exercise-induced adaptations.
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Affiliation(s)
- Minas Nalbandian
- Graduate School of Sports and Health Science, Doshisha University, Kyoto 610-0394, Japan.
| | - Masaki Takeda
- Faculty of Sports and Health Science, Doshisha University, Kyoto 610-0394, Japan.
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Wanders D, Graff EC, Judd RL. Effects of high fat diet on GPR109A and GPR81 gene expression. Biochem Biophys Res Commun 2012; 425:278-83. [PMID: 22842580 DOI: 10.1016/j.bbrc.2012.07.082] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 07/17/2012] [Indexed: 11/27/2022]
Abstract
GPR109A (PUMA-G, NIACR1, HCA(2)) and GPR81 (HCA(1)) are G protein-coupled receptors located predominantly on adipocytes that mediate anti-lipolytic effects. These cell surface receptors give the adipocyte the ability to "sense" metabolic changes in the environment and respond through lipolytic regulation and release of products including free fatty acids and pro- or anti-inflammatory adipokines. The endogenous ligands for GPR109A and GPR81 are β-hydroxybutyrate and lactate, respectively, both of which are hydroxycarboxylic acids and intermediates of energy metabolism. Circulating β-hydroxybutyrate levels are increased during a 2-3 day fast and prolonged starvation, while lactate levels are elevated during times of intense exercise. Therefore, regulation of expression of these receptors is crucial for the metabolic sensing ability of the adipocyte and ultimately whole body energy homeostasis. We investigated the effects of high fat diet-induced obesity on expression of GPR109A and GPR81. Sixteen male C57BL/6 mice were placed on a control (10% kcal fat; n=8) or a high fat (60% kcal fat; n=8) diet for 11 weeks. Diet-induced obesity significantly reduced GPR109A and GPR81 gene expression in epididymal fat pads. This decrease in GPR109A and GPR81 gene expression was positively correlated with a decrease in adipose tissue PPARγ gene expression. In contrast, acute treatment of both 3T3-L1 adipocytes and RAW 264.7 macrophages with lipopolysaccharide significantly increased GPR109A gene expression, but had no effect on GPR81 expression in 3T3-L1 adipocytes. In conclusion, chronic obesity reduces GPR109A and GPR81 expression in the adipose tissue, while acute in vitro LPS treatment increases expression of GPR109A in adipocytes and macrophages.
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Affiliation(s)
- Desiree Wanders
- Department of Anatomy, Physiology and Pharmacology, Auburn University, 219 Greene Hall, Auburn, AL 36849-5518, USA
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Abstract
Abnormal blood lipids are the major modifiable risk factor underlying the development of cardiovascular disease. Niacin has a profound ability to reduce low-density lipoprotein-C, very low-density lipoprotein-C and triglycerides and is the most effective pharmacological agent to increase high-density lipoprotein-C. Recently, the receptor for niacin, GPR109A, was discovered. GPR109A in the adipocyte mediates a niacin-induced inhibition of lipolysis, which could play a crucial part in its role as a lipid-modifying drug. GPR109A in epidermal Langerhans cells mediates flushing, an unwanted side effect of niacin therapy. For the past decade, the functions of GPR109A have been studied and full or partial agonists have been developed in an attempt to achieve the beneficial effects of niacin while avoiding the unwanted flushing side effect. This review presents what is known to date about GPR109A biology and function and the future of GPR109A as a pharmacological target.
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Affiliation(s)
- D Wanders
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
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Feingold KR, Moser A, Shigenaga JK, Grunfeld C. Inflammation inhibits GPR81 expression in adipose tissue. Inflamm Res 2011; 60:991-5. [PMID: 21751047 DOI: 10.1007/s00011-011-0361-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Accepted: 06/27/2011] [Indexed: 12/14/2022] Open
Abstract
OBJECTIVE AND DESIGN The aim of this study was to examine the expression of G protein-coupled receptor 81 (GPR81) in mouse adipose tissue in response to inflammatory stimuli. GPR81 is activated by lactate resulting in the inhibition of lipolysis. MATERIALS AND TREATMENT Mice were injected with saline, lipopolysaccharide (LPS), zymosan, or turpentine, N = 5 per group. 3T3-L1 adipocytes were treated with tumor necrosis factor alpha, interleukin (IL)-l beta, IL-6, or interferon gamma. METHODS GPR81 expression levels were measured by real-time PCR and statistical significance was determined by Student's t test. RESULTS LPS resulted in a marked decrease in GPR81 mRNA level in mouse adipose tissue in C57BL/6 and OuJ mice, an effect that was not observed in HeJ mice, which have a mutation in TLR4. Zymosan and turpentine also decreased adipose tissue GPR81 expression. Cytokine treatment of 3T3-L1 adipocytes had no effect on GPR81 expression. GPR81 expression was decreased in ob/ob mice, an animal model of type 2 diabetes that is characterized by inflammation. CONCLUSION Inflammation decreases the expression of GPR81 in adipose tissue.
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Affiliation(s)
- Kenneth R Feingold
- Metabolism Section (111F), Department of Veterans Affairs Medical Center, University of California San Francisco, 4150 Clement Street, San Francisco, CA 94121, USA.
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Cai TQ, Ren N, Jin L, Cheng K, Kash S, Chen R, Wright SD, Taggart AK, Waters MG. Role of GPR81 in lactate-mediated reduction of adipose lipolysis. Biochem Biophys Res Commun 2008; 377:987-91. [DOI: 10.1016/j.bbrc.2008.10.088] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Accepted: 10/19/2008] [Indexed: 10/21/2022]
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Abstract
This article reviews the effects of acute and chronic exercise on the fatty-acid composition of animal and human tissues (plasma, skeletal muscle, heart, adipose tissue, liver, artery and erythrocytes), as reported in 68 studies spanning four decades. The most consistently observed effect has been an increase in the relative amount of unsaturated, especially monounsaturated, non-esterified fatty acids in plasma of both animals and humans after acute exercise. Chronic exercise seems to increase the proportion of polyunsaturated fatty acids and omega6 fatty acids, while decreasing the proportion of monounsaturated fatty acids in animal and human adipose tissue. Additionally, chronic exercise seems to decrease the relative amount of unsaturated fatty acids in liver lipids of animals and humans. There is no consensus regarding the effect of exercise on the fatty-acid composition of lipids in any other tissue. In general, the effects of exercise are independent of nutrition and, regarding skeletal muscle, muscle fibre type. The available literature shows that, in addition to modifying the concentrations of animal and human tissue lipids, exercise also changes their fatty-acid profile. Unfortunately, the available studies are so much divided among exercise models, species and biological samples that a cohesive picture of the plasticity of the fatty-acid pattern of most tissues toward exercise has not emerged. Future studies should focus on determining the fatty-acid profile of separate lipid classes (rather than total lipids) in separate subcellular fractions (rather than whole tissues), examining tissues and organs on which no data are available and exploring the mechanisms of the exercise-induced changes in fatty-acid composition.
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Affiliation(s)
- Michalis G Nikolaidis
- Department of Physical Education and Sport Science, Aristotle University of Thessaloniki, Thessaloniki, 541 24 Thessaloniki, Greece
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Pearce FJ, Connett RJ. Effect of lactate and palmitate on substrate utilization of isolated rat soleus. THE AMERICAN JOURNAL OF PHYSIOLOGY 1980; 238:C149-59. [PMID: 6990780 DOI: 10.1152/ajpcell.1980.238.5.c149] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The effects of exogenous lactate and palmitate on the metabolism of rat soleus muscle were studied. In the presence of glucose and insulin, the addition of 8 mM lactate resulted in a decrease in the oxidation of both glucose and other substrates. Lactate accounted for 70% of the oxygen consumption under these conditions. Glycogen accumulation and the incorporation of exogenous palmitate into triglycerides were stimulated by lactate addition, whereas the utilization of exogenous glycerol was depressed. The addition of 1 mM palmitate in either the presence or absence of lactate resulted in an inhibition of both glycolysis and the utilization of exogenous glucose. The results are discussed in terms of the effect of lactate levels on recovery from exercise.
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Dieterle P, Dieterle C, Bottermann P, Schwarz K, Henner J. [The influence of lactic acid on rat adipose tissue lipolysis in vitro]. Diabetologia 1969; 5:238-42. [PMID: 5391192 DOI: 10.1007/bf01212091] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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