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Abstract
The present paper reviews the physiological responses of human liver carbohydrate metabolism to physical activity and ingestion of dietary sugars. The liver represents a central link in human carbohydrate metabolism and a mechanistic crux point for the effects of dietary sugars on athletic performance and metabolic health. As a corollary, knowledge regarding physiological responses to sugar ingestion has potential application to either improve endurance performance in athletes, or target metabolic diseases in people who are overweight, obese and/or sedentary. For example, exercise increases whole-body glycogen utilisation, and the breakdown of liver glycogen to maintain blood glucose concentrations becomes increasingly important as exercise intensity increases. Accordingly, prolonged exercise at moderate-to-high exercise intensity results in depletion of liver glycogen stores unless carbohydrate is ingested during exercise. The exercise-induced glycogen deficit can increase insulin sensitivity and blood glucose control, and may result in less hepatic lipid synthesis. Therefore, the induction and maintenance of a glycogen deficit with exercise could be a specific target to improve metabolic health and could be achieved by carbohydrate (sugar) restriction before, during and/or after exercise. Conversely, for athletes, maintaining and restoring these glycogen stores is a priority when competing in events requiring repeated exertion with limited recovery. With this in mind, evidence consistently demonstrates that fructose-containing sugars accelerate post-exercise liver glycogen repletion and could reduce recovery time by as much as half that seen with ingestion of glucose (polymers)-only. Therefore, athletes aiming for rapid recovery in multi-stage events should consider ingesting fructose-containing sugars to accelerate recovery.
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Morales-Alamo D, Guerra B, Santana A, Martin-Rincon M, Gelabert-Rebato M, Dorado C, Calbet JAL. Skeletal Muscle Pyruvate Dehydrogenase Phosphorylation and Lactate Accumulation During Sprint Exercise in Normoxia and Severe Acute Hypoxia: Effects of Antioxidants. Front Physiol 2018; 9:188. [PMID: 29615918 PMCID: PMC5867337 DOI: 10.3389/fphys.2018.00188] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 02/23/2018] [Indexed: 12/30/2022] Open
Abstract
Compared to normoxia, during sprint exercise in severe acute hypoxia the glycolytic rate is increased leading to greater lactate accumulation, acidification, and oxidative stress. To determine the role played by pyruvate dehydrogenase (PDH) activation and reactive nitrogen and oxygen species (RNOS) in muscle lactate accumulation, nine volunteers performed a single 30-s sprint (Wingate test) on four occasions: two after the ingestion of placebo and another two following the intake of antioxidants, while breathing either hypoxic gas (PIO2 = 75 mmHg) or room air (PIO2 = 143 mmHg). Vastus lateralis muscle biopsies were obtained before, immediately after, 30 and 120 min post-sprint. Antioxidants reduced the glycolytic rate without altering performance or VO2. Immediately after the sprints, Ser293- and Ser300-PDH-E1α phosphorylations were reduced to similar levels in all conditions (~66 and 91%, respectively). However, 30 min into recovery Ser293-PDH-E1α phosphorylation reached pre-exercise values while Ser300-PDH-E1α was still reduced by 44%. Thirty minutes after the sprint Ser293-PDH-E1α phosphorylation was greater with antioxidants, resulting in 74% higher muscle lactate concentration. Changes in Ser293 and Ser300-PDH-E1α phosphorylation from pre to immediately after the sprints were linearly related after placebo (r = 0.74, P < 0.001; n = 18), but not after antioxidants ingestion (r = 0.35, P = 0.15). In summary, lactate accumulation during sprint exercise in severe acute hypoxia is not caused by a reduced activation of the PDH. The ingestion of antioxidants is associated with increased PDH re-phosphorylation and slower elimination of muscle lactate during the recovery period. Ser293 re-phosphorylates at a faster rate than Ser300-PDH-E1α during the recovery period, suggesting slightly different regulatory mechanisms.
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Affiliation(s)
- David Morales-Alamo
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain
| | - Borja Guerra
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain
| | - Alfredo Santana
- Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain.,Clinical Genetics Unit, Complejo Hospitalario Universitario Insular-Materno Infantil de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Marcos Martin-Rincon
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain
| | - Miriam Gelabert-Rebato
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain
| | - Cecilia Dorado
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain
| | - José A L Calbet
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences, Las Palmas de Gran Canaria, Spain
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3
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Regulation of Muscle Glycogen Metabolism during Exercise: Implications for Endurance Performance and Training Adaptations. Nutrients 2018; 10:nu10030298. [PMID: 29498691 PMCID: PMC5872716 DOI: 10.3390/nu10030298] [Citation(s) in RCA: 119] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 02/23/2018] [Accepted: 02/27/2018] [Indexed: 11/16/2022] Open
Abstract
Since the introduction of the muscle biopsy technique in the late 1960s, our understanding of the regulation of muscle glycogen storage and metabolism has advanced considerably. Muscle glycogenolysis and rates of carbohydrate (CHO) oxidation are affected by factors such as exercise intensity, duration, training status and substrate availability. Such changes to the global exercise stimulus exert regulatory effects on key enzymes and transport proteins via both hormonal control and local allosteric regulation. Given the well-documented effects of high CHO availability on promoting exercise performance, elite endurance athletes are typically advised to ensure high CHO availability before, during and after high-intensity training sessions or competition. Nonetheless, in recognition that the glycogen granule is more than a simple fuel store, it is now also accepted that glycogen is a potent regulator of the molecular cell signaling pathways that regulate the oxidative phenotype. Accordingly, the concept of deliberately training with low CHO availability has now gained increased popularity amongst athletic circles. In this review, we present an overview of the regulatory control of CHO metabolism during exercise (with a specific emphasis on muscle glycogen utilization) in order to discuss the effects of both high and low CHO availability on modulating exercise performance and training adaptations, respectively.
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The Effects of Maximally Achievable Cycling Cadence on Carbohydrate Management at Moderate and Heavy Exercise Intensity. Int J Sports Physiol Perform 2018; 13:64-68. [PMID: 28459286 DOI: 10.1123/ijspp.2016-0555] [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: 11/18/2022]
Abstract
Effects of different cycling cadences (revolutions/min [rpm]) on metabolic rate, blood lactate concentration (BLC), and reliance on carbohydrate (CHO) defined as the fraction of oxygen uptake used for CHO oxidation (relCHO) are highly individual. Whether this depends on the individually maximal achievable rpm obtained at minimized cycling resistance (rpmmax) is unknown. The authors tested the hypotheses that the individual freely chosen rpm in an incremental cycle-ergometer test (ILT) and relCHO at given BLC levels both depend on rpmmax. Seven master cyclists and 8 not specifically trained leisure athletes performed an ILT at individually freely chosen rpm and an rpmmax test. Respiratory data and BLC were measured; relCHO was plotted as a function of the BLC for the determinations of the individual BLC at relCHO of 75% and 95% (BLC75% and BLC95%). With 16.7%, the between-subjects variability of individual rpm was high but independent from rpmmax. In the master athletes, rpmmax explained 59.3% and 95.2% of BLC75% (P = .043) and BLC95% (P = .001), respectively. Irrespective of cycling experience, the individually preferred average rpm at submaximal stages of an ILT is highly variable and independent of rpmmax. In experienced cyclists, carbohydrate management defined as the ratio between substrate availability as indicated by BLC and relCHO depends on rpmmax.
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Gudiksen A, Bertholdt L, Stankiewicz T, Tybirk J, Plomgaard P, Bangsbo J, Pilegaard H. Effects of training status on PDH regulation in human skeletal muscle during exercise. Pflugers Arch 2017; 469:1615-1630. [PMID: 28801776 DOI: 10.1007/s00424-017-2019-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 06/13/2017] [Accepted: 06/14/2017] [Indexed: 12/23/2022]
Abstract
Pyruvate dehydrogenase (PDH) is the gateway enzyme for carbohydrate-derived pyruvate feeding into the TCA cycle. PDH may play a central role in regulating substrate shifts during exercise, but the influence of training state on PDH regulation during exercise is not fully elucidated. The purpose of this study was to investigate the impact of training state on post-translational regulation of PDHa activity during submaximal and exhaustive exercise. Eight untrained and nine endurance exercise-trained healthy male subjects performed incremental exercise on a cycle ergometer: 40 min at 50% incremental peak power output (IPPO), 10 min at 65% (IPPO), followed by 80% (IPPO) until exhaustion. Trained subjects had higher (P < 0.05) PDH-E1α, PDK1, PDK2, PDK4, and PDP1 protein content as well as PDH phosphorylation and PDH acetylation. Exercising at the same relative intensity led to similar muscle PDH activation in untrained and trained subjects, whereas PDHa activity at exhaustion was higher (P < 0.05) in trained than untrained. Furthermore, exercise induced similar PDH dephosphorylation in untrained and trained subjects, while PDH acetylation was increased (P < 0.05) only in trained subjects. In conclusion, PDHa activity and PDH dephosphorylation were well adjusted to the relative exercise intensity during submaximal exercise. In addition, higher PDHa activity in trained than untrained at exhaustion seemed related to differences in glycogen utilization rather than differences in PDH phosphorylation and acetylation state, although site-specific contributions cannot be ruled out.
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Affiliation(s)
- Anders Gudiksen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, August Krogh Building, Universitetsparken 13, 2100, Copenhagen, Denmark
| | - Lærke Bertholdt
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, August Krogh Building, Universitetsparken 13, 2100, Copenhagen, Denmark
| | - Tomasz Stankiewicz
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, August Krogh Building, Universitetsparken 13, 2100, Copenhagen, Denmark
| | - Jonas Tybirk
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Peter Plomgaard
- Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark.,Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Jens Bangsbo
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Henriette Pilegaard
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, August Krogh Building, Universitetsparken 13, 2100, Copenhagen, Denmark.
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Chen YC, Travers RL, Walhin JP, Gonzalez JT, Koumanov F, Betts JA, Thompson D. Feeding influences adipose tissue responses to exercise in overweight men. Am J Physiol Endocrinol Metab 2017; 313:E84-E93. [PMID: 28292758 DOI: 10.1152/ajpendo.00006.2017] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 02/22/2017] [Accepted: 03/09/2017] [Indexed: 01/04/2023]
Abstract
Feeding profoundly affects metabolic responses to exercise in various tissues, but the effect of feeding status on human adipose tissue responses to exercise has never been studied. Ten healthy overweight men aged 26 ± 5 yr (mean ± SD) with a waist circumference of 105 ± 10 cm walked at 60% of maximum oxygen uptake under either fasted or fed conditions in a randomized, counterbalanced design. Feeding comprised 648 ± 115 kcal 2 h before exercise. Blood samples were collected at regular intervals to examine changes in metabolic parameters and adipokine concentrations. Adipose tissue samples were obtained at baseline and 1 h after exercise to examine changes in adipose tissue mRNA expression and secretion of selected adipokines ex vivo. Adipose tissue mRNA expression of pyruvate dehydrogenase kinase isozyme 4 (PDK4), adipose triglyceride lipase, hormone-sensitive lipase (HSL), fatty acid translocase/CD36, glucose transporter type 4 (GLUT4), and insulin receptor substrate 2 (IRS2) in response to exercise were lower in fed compared with fasted conditions (all P ≤ 0.05). Postexercise adipose IRS2 protein was affected by feeding (P ≤ 0.05), but Akt2, AMPK, IRS1, GLUT4, PDK4, and HSL protein levels were not different. Feeding status did not impact serum and ex vivo adipose secretion of IL-6, leptin, or adiponectin in response to exercise. This is the first study to show that feeding before acute exercise affects postexercise adipose tissue gene expression, and we propose that feeding is likely to blunt long-term adipose tissue adaptation to regular exercise.
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Affiliation(s)
- Yung-Chih Chen
- Department for Health, University of Bath, Bath, United Kingdom
| | | | | | | | | | - James A Betts
- Department for Health, University of Bath, Bath, United Kingdom
| | - Dylan Thompson
- Department for Health, University of Bath, Bath, United Kingdom
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7
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Gudiksen A, Bertholdt L, Vingborg MB, Hansen HW, Ringholm S, Pilegaard H. Muscle interleukin-6 and fasting-induced PDH regulation in mouse skeletal muscle. Am J Physiol Endocrinol Metab 2017; 312:E204-E214. [PMID: 28028037 DOI: 10.1152/ajpendo.00291.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 12/19/2016] [Accepted: 12/20/2016] [Indexed: 11/22/2022]
Abstract
Fasting prompts a metabolic shift in substrate utilization from carbohydrate to predominant fat oxidation in skeletal muscle, and pyruvate dehydrogenase (PDH) is seen as a controlling link between the competitive oxidation of carbohydrate and fat during metabolic challenges like fasting. Interleukin (IL)-6 has been proposed to be released from muscle with concomitant effects on both glucose and fat utilization. The aim was to test the hypothesis that muscle IL-6 has a regulatory impact on fasting-induced suppression of skeletal muscle PDH. Skeletal muscle-specific IL-6 knockout (IL-6 MKO) mice and floxed littermate controls (control) were either fed or fasted for 6 or 18 h. Lack of muscle IL-6 elevated the respiratory exchange ratio in the fed and early fasting state, but not with prolonged fasting. Activity of PDH in the active form (PDHa) was higher in fed and fasted IL-6 MKO than in control mice at 18 h, but not at 6 h, whereas lack of muscle IL-6 did not prevent downregulation of PDHa activity in skeletal muscle or changes in plasma and muscle substrate levels in response to 18 h of fasting. Phosphorylation of three of four sites on PDH-E1α increased with 18 h of fasting, but was lower in IL-6 MKO mice than in control. In addition, both PDK4 mRNA and protein increased with 6 and 18 h of fasting in both genotypes, but PDK4 protein was lower in IL-6 MKO than in control. In conclusion, skeletal muscle IL-6 seems to regulate whole body substrate utilization in the fed, but not fasted, state and influence skeletal muscle PDHa activity in a circadian manner. However, skeletal muscle IL-6 is not required for maintaining metabolic flexibility in response to fasting.
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Affiliation(s)
- Anders Gudiksen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Laerke Bertholdt
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Mikkel Birkkjaer Vingborg
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Henriette Watson Hansen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Stine Ringholm
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Henriette Pilegaard
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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8
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Bertholdt L, Gudiksen A, Schwartz CL, Knudsen JG, Pilegaard H. Lack of skeletal muscle IL-6 influences hepatic glucose metabolism in mice during prolonged exercise. Am J Physiol Regul Integr Comp Physiol 2017; 312:R626-R636. [PMID: 28122718 DOI: 10.1152/ajpregu.00373.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 01/23/2017] [Accepted: 01/23/2017] [Indexed: 01/06/2023]
Abstract
The liver is essential in maintaining and regulating glucose homeostasis during prolonged exercise. IL-6 has been shown to be secreted from skeletal muscle during exercise and has been suggested to signal to the liver. Therefore, the aim of this study was to investigate the role of skeletal muscle IL-6 on hepatic glucose regulation and substrate choice during prolonged exercise. Skeletal muscle-specific IL-6 knockout (IL-6 MKO) mice (age, 12-14 wk) and littermate lox/lox (Control) mice were either rested (Rest) or completed a single bout of exercise for 10, 60, or 120 min, and the liver was quickly obtained. Hepatic IL-6 mRNA was higher at 60 min of exercise, and hepatic signal transducer and activator of transcription 3 was higher at 120 min of exercise than at rest in both genotypes. Hepatic glycogen was higher in IL-6 MKO mice than control mice at rest, but decreased similarly during exercise in the two genotypes, and hepatic glucose content was lower in IL-6 MKO than control mice at 120 min of exercise. Hepatic phosphoenolpyruvate carboxykinase mRNA and protein increased in both genotypes at 120 min of exercise, whereas hepatic glucose 6 phosphatase protein remained unchanged. Furthermore, IL-6 MKO mice had higher hepatic pyruvate dehydrogenase (PDH)Ser232 and PDHSer300 phosphorylation than control mice at rest. In conclusion, hepatic gluconeogenic capacity in mice is increased during prolonged exercise independent of muscle IL-6. Furthermore, Skeletal muscle IL-6 influences hepatic substrate regulation at rest and hepatic glucose metabolism during prolonged exercise, seemingly independent of IL-6 signaling in the liver.
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Affiliation(s)
- Lærke Bertholdt
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Anders Gudiksen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | - Jakob G Knudsen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
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9
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Gudiksen A, Schwartz CL, Bertholdt L, Joensen E, Knudsen JG, Pilegaard H. Lack of Skeletal Muscle IL-6 Affects Pyruvate Dehydrogenase Activity at Rest and during Prolonged Exercise. PLoS One 2016; 11:e0156460. [PMID: 27327080 PMCID: PMC4915712 DOI: 10.1371/journal.pone.0156460] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 05/13/2016] [Indexed: 12/12/2022] Open
Abstract
Pyruvate dehydrogenase (PDH) plays a key role in the regulation of skeletal muscle substrate utilization. IL-6 is produced in skeletal muscle during exercise in a duration dependent manner and has been reported to increase whole body fatty acid oxidation, muscle glucose uptake and decrease PDHa activity in skeletal muscle of fed mice. The aim of the present study was to examine whether muscle IL-6 contributes to exercise-induced PDH regulation in skeletal muscle. Skeletal muscle-specific IL-6 knockout (IL-6 MKO) mice and floxed littermate controls (control) completed a single bout of treadmill exercise for 10, 60 or 120 min, with rested mice of each genotype serving as basal controls. The respiratory exchange ratio (RER) was overall higher (P<0.05) in IL-6 MKO than control mice during the 120 min of treadmill exercise, while RER decreased during exercise independent of genotype. AMPK and ACC phosphorylation also increased with exercise independent of genotype. PDHa activity was in control mice higher (P<0.05) at 10 and 60 min of exercise than at rest but remained unchanged in IL-6 MKO mice. In addition, PDHa activity was higher (P<0.05) in IL-6 MKO than control mice at rest and 60 min of exercise. Neither PDH phosphorylation nor acetylation could explain the genotype differences in PDHa activity. Together, this provides evidence that skeletal muscle IL-6 contributes to the regulation of PDH at rest and during prolonged exercise and suggests that muscle IL-6 normally dampens carbohydrate utilization during prolonged exercise via effects on PDH.
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Affiliation(s)
- Anders Gudiksen
- Section for cell biology and physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- * E-mail:
| | - Camilla Lindgren Schwartz
- Section for cell biology and physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Lærke Bertholdt
- Section for cell biology and physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Ella Joensen
- Section for cell biology and physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Jakob G. Knudsen
- Section for cell biology and physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Henriette Pilegaard
- Section for cell biology and physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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Beneke R, Alkhatib A. High cycling cadence reduces carbohydrate oxidation at given low intensity metabolic rate. Biol Sport 2015; 32:27-33. [PMID: 25729147 PMCID: PMC4314601 DOI: 10.5604/20831862.1126325] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 08/02/2014] [Accepted: 09/12/2014] [Indexed: 12/25/2022] Open
Abstract
Cycling cadence (RPM)-related differences in blood lactate concentration (BLC) increase with increasing exercise intensity, whilst corresponding divergences in oxygen uptake (V.O2) and carbon dioxide production (V.CO2) decrease. Aim of the present study was to test whether a higher RPM reduces the fraction (%) of the V.O2 used for carbohydrate oxidation (relCHO) at a given BLC. Eight males (23.9 ± 1.6 yrs; 177 ± 3 cm; 70.3 ± 3.4 kg) performed incremental load tests at 50 and 100 RPM. BLC, V.O2 and V.CO2 were measured. At respiratory exchange ratios (RER) < 1, relCHO were calculated and the constant determining 50 % relCHO (kCHO) was approximated as a function of the BLC. At submaximal workload V.O2, V.CO2, and relCHO were lower (all p < 0.002; η2 > 0.209) at 50 than at 100 RPM. No differences were observed in V.O2peak (3.96 ± 0.22 vs. 4.00 ± 0.25 l · min−1) and RERpeak (1.18 ± 0.02 vs. 1.15 ± 0.02). BLC was lower (p < 0.001; η2 = 0.680) at 50 than at 100 RPM irrespective of cycling intensity. At 50 RPM, kCHO (4.2 ± 1.4 (mmol · l−1)3) was lower (p = 0.043; η2 = 0.466) than at 100 RPM (5.9 ± 1.9 (mmol · l−1)3). This difference in kCHO reflects a reduced CHO oxidation at a given BLC at 100 than at 50 RPM. At a low exercise intensity, a higher cycling cadence can substantially reduce the reliance on CHO at a given metabolic rate and/or BLC.
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Affiliation(s)
- R Beneke
- Abt. Medizin, Training und Gesundheit, Inst. Sportwissenschaft und Motologie, Philipps Universität Marburg, Germany
| | - A Alkhatib
- Academy of Sport and Sport & Physical Activity, Sheffield Hallam University, United Kingdom
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11
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Exercise-induced regulation of key factors in substrate choice and gluconeogenesis in mouse liver. Mol Cell Biochem 2015; 403:209-17. [PMID: 25702176 DOI: 10.1007/s11010-015-2351-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 02/06/2015] [Indexed: 12/17/2022]
Abstract
As the demand for hepatic glucose production increases during exercise, regulation of liver substrate choice and gluconeogenic activity becomes essential. The aim of the present study was to investigate the effect of a single exercise bout on gluconeogenic protein content and regulation of enzymes involved in substrate utilization in the liver. Mice were subjected to 1 h of treadmill exercise, and livers were removed immediately, 4 or 10 h after exercise. Glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxylase (PEPCK) mRNA contents in the liver increased immediately after exercise, while the PEPCK protein content increased at 10 h of recovery. Furthermore, 5'AMP-activated protein kinase (AMPK), acetyl-CoA carboxylase (ACC), and pyruvate dehydrogenase (PDH)-E1α Ser(293) phosphorylations decreased immediately after exercise. In addition, PDH kinase 4 (PDK4) mRNA and protein content increased immediately after exercise and at 10 h of recovery, respectively. These findings suggest that acute changes in PEPCK and G6Pase protein contents do not contribute to the regulation of gluconeogenic enzyme activity during 1 h of non-exhaustive exercise. In addition, the observation that PDH-E1α, AMPK, and ACC phosphorylation decreased immediately after exercise may indicate that carbohydrates rather than fatty acids are utilized for oxidation in the liver during non-exhaustive exercise.
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12
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Exercise-induced AMPK and pyruvate dehydrogenase regulation is maintained during short-term low-grade inflammation. Pflugers Arch 2014; 467:341-50. [PMID: 24691558 PMCID: PMC4293495 DOI: 10.1007/s00424-014-1499-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 02/25/2014] [Accepted: 03/07/2014] [Indexed: 12/18/2022]
Abstract
The aim of the present study was to examine the effect of lipopolysaccharide (LPS)-induced inflammation on AMP-activated protein kinase (AMPK) and pyruvate dehydrogenase (PDH) regulation in human skeletal muscle at rest and during exercise. Nine young healthy physically inactive male subjects completed two trials. In an LPS trial, the subjects received a single LPS injection (0.3 ng/kg body weight) and blood samples and vastus lateralis muscle biopsies were obtained before and 2 h after the LPS injection and immediately after a 10-min one-legged knee extensor exercise bout performed approximately 2½ h after the LPS injection. The exercise bout with muscle samples obtained before and immediately after was repeated in a control trial without LPS injection. The plasma tumor necrosis factor α concentration increased 17-fold 2 h after LPS relative to before. Muscle lactate and muscle glycogen were unchanged from before to 2 h after LPS and exercise increased muscle lactate and decreased muscle glycogen in the control (P < 0.05) and the LPS (0.05 ≤ P < 0.1) trial with no differences between the trials. AMPK, acetyl-CoA carboxylase (ACC) and PDH phosphorylation as well as PDHa activity were unaffected 2 h after LPS relative to before. Exercise decreased (P < 0.05) PDH and increased (P < 0.05) AMPK and ACC phosphorylation as well as increased (P < 0.05) PDHa activity similarly in the LPS and control trial. In conclusion, LPS-induced inflammation does not affect resting or exercise-induced AMPK and PDH regulation in human skeletal muscle. This suggests that metabolic flexibility during exercise is maintained during short-term low-grade inflammation in humans.
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13
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Gray LR, Tompkins SC, Taylor EB. Regulation of pyruvate metabolism and human disease. Cell Mol Life Sci 2013; 71:2577-604. [PMID: 24363178 PMCID: PMC4059968 DOI: 10.1007/s00018-013-1539-2] [Citation(s) in RCA: 509] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 11/24/2013] [Accepted: 12/02/2013] [Indexed: 12/31/2022]
Abstract
Pyruvate is a keystone molecule critical for numerous aspects of eukaryotic and human metabolism. Pyruvate is the end-product of glycolysis, is derived from additional sources in the cellular cytoplasm, and is ultimately destined for transport into mitochondria as a master fuel input undergirding citric acid cycle carbon flux. In mitochondria, pyruvate drives ATP production by oxidative phosphorylation and multiple biosynthetic pathways intersecting the citric acid cycle. Mitochondrial pyruvate metabolism is regulated by many enzymes, including the recently discovered mitochondria pyruvate carrier, pyruvate dehydrogenase, and pyruvate carboxylase, to modulate overall pyruvate carbon flux. Mutations in any of the genes encoding for proteins regulating pyruvate metabolism may lead to disease. Numerous cases have been described. Aberrant pyruvate metabolism plays an especially prominent role in cancer, heart failure, and neurodegeneration. Because most major diseases involve aberrant metabolism, understanding and exploiting pyruvate carbon flux may yield novel treatments that enhance human health.
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Affiliation(s)
- Lawrence R Gray
- Department of Biochemistry, Fraternal Order of the Eagles Diabetes Research Center, and François M. Abboud Cardiovascular Research Center, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 51 Newton Rd, 4-403 BSB, Iowa City, IA, 52242, USA
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Herbst EAF, MacPherson REK, LeBlanc PJ, Roy BD, Jeoung NH, Harris RA, Peters SJ. Pyruvate dehydrogenase kinase-4 contributes to the recirculation of gluconeogenic precursors during postexercise glycogen recovery. Am J Physiol Regul Integr Comp Physiol 2013; 306:R102-7. [PMID: 24305065 DOI: 10.1152/ajpregu.00150.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During recovery from glycogen-depleting exercise, there is a shift from carbohydrate oxidation to glycogen resynthesis. The activity of the pyruvate dehydrogenase (PDH) complex may decrease to reduce oxidation of carbohydrates in favor of increasing gluconeogenic recycling of carbohydrate-derived substrates for this process. The precise mechanism behind this has yet to be elucidated; however, research examining mRNA content has suggested that the less-abundant pyruvate dehydrogenase kinase-4 (PDK4) may reduce PDH activation during exercise recovery. To investigate this, skeletal muscle and liver of wild-type (WT) and PDK4-knockout (PDK4-KO) mice were analyzed at rest (Rest), after exercise to exhaustion (Exh), and after 2 h of recovery with ad libitum feeding (Rec). Although there were no differences in exercise tolerance between genotypes, caloric consumption was doubled by PDK4-KO mice during Rec. Because of this, PDK4-KO mice at Rec supercompensated muscle glycogen to 120% of resting stores. Therefore, an extra group of PDK4-KO mice were pair-fed (PF) with WT mice during Rec for comparison. PF mice fully replenished muscle glycogen but recovered only 50% of liver glycogen stores. Concentrations of muscle lactate and alanine were also lower in PF than in WT mice, indicating that this decrease may lead to a potential reduction of recycled gluconeogenic substrates, due to oxidation of their carbohydrate precursors in skeletal muscle, leading to observed reductions in hepatic glucose and glycogen concentrations. Because of the impairments seen in PF PDK4-KO mice, these results suggest a role for PDK4 in regulating the PDH complex in muscle and promoting gluconeogenic precursor recirculation during recovery from exhaustive exercise.
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Affiliation(s)
- Eric A F Herbst
- Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
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15
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Biensø RS, Knudsen JG, Brandt N, Pedersen PA, Pilegaard H. Effects of IL-6 on pyruvate dehydrogenase regulation in mouse skeletal muscle. Pflugers Arch 2013; 466:1647-57. [PMID: 24221357 PMCID: PMC4092239 DOI: 10.1007/s00424-013-1399-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 10/28/2013] [Accepted: 10/29/2013] [Indexed: 12/28/2022]
Abstract
Skeletal muscle regulates substrate choice according to demand and availability and pyruvate dehydrogenase (PDH) is central in this regulation. Circulating interleukin (IL)-6 increases during exercise and IL-6 has been suggested to increase whole body fat oxidation. Furthermore, IL-6 has been reported to increase AMP-activated protein kinase (AMPK) phosphorylation and AMPK suggested to regulate PDHa activity. Together, this suggests that IL-6 may be involved in regulating PDH. The aim of this study was to investigate the effect of a single injection of IL-6 on PDH regulation in skeletal muscle in fed and fasted mice. Fed and 16-18 h fasted mice were injected with either 3 ng · g(-1) recombinant mouse IL-6 or PBS as control. Fasting markedly reduced plasma glucose, muscle glycogen, muscle PDHa activity, as well as increased PDK4 mRNA and protein content in skeletal muscle. IL-6 injection did not affect plasma glucose or muscle glycogen, but increased AMPK and ACC phosphorylation and tended to decrease p38 protein content in skeletal muscle in fasted mice. In addition IL-6 injection reduced PDHa activity in fed mice and increased PDHa activity in fasted mice without significant changes in PDH-E1α phosphorylation or PDP1 and PDK4 mRNA and protein content. The present findings suggest that IL-6 contributes to regulating the PDHa activity and hence carbohydrate oxidation, but the metabolic state of the muscle seems to determine the outcome of this regulation. In addition, AMPK and p38 may contribute to the IL-6-mediated PDH regulation in the fasted state.
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Affiliation(s)
- Rasmus S. Biensø
- Centre of Inflammation and Metabolism and The August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Jakob G. Knudsen
- Centre of Inflammation and Metabolism and The August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Nina Brandt
- Centre of Inflammation and Metabolism and The August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Present Address: Exercise and Metabolic Disease Research Laboratory, Translational Sciences Section, School of Nursing, University of California, Los Angeles, CA USA
| | - Per A. Pedersen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Henriette Pilegaard
- Centre of Inflammation and Metabolism and The August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Universitesparken 13, 2100 Copenhagen Ø, Denmark
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Constantin-Teodosiu D. Regulation of muscle pyruvate dehydrogenase complex in insulin resistance: effects of exercise and dichloroacetate. Diabetes Metab J 2013; 37:301-14. [PMID: 24199158 PMCID: PMC3816130 DOI: 10.4093/dmj.2013.37.5.301] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Since the mitochondrial pyruvate dehydrogenase complex (PDC) controls the rate of carbohydrate oxidation, impairment of PDC activity mediated by high-fat intake has been advocated as a causative factor for the skeletal muscle insulin resistance, metabolic syndrome, and the onset of type 2 diabetes (T2D). There are also situations where muscle insulin resistance can occur independently from high-fat dietary intake such as sepsis, inflammation, or drug administration though they all may share the same underlying mechanism, i.e., via activation of forkhead box family of transcription factors, and to a lower extent via peroxisome proliferator-activated receptors. The main feature of T2D is a chronic elevation in blood glucose levels. Chronic systemic hyperglycaemia is toxic and can lead to cellular dysfunction that may become irreversible over time due to deterioration of the pericyte cell's ability to provide vascular stability and control to endothelial proliferation. Therefore, it may not be surprising that T2D's complications are mainly macrovascular and microvascular related, i.e., neuropathy, retinopathy, nephropathy, coronary artery, and peripheral vascular diseases. However, life style intervention such as exercise, which is the most potent physiological activator of muscle PDC, along with pharmacological intervention such as administration of dichloroacetate or L-carnitine can prove to be viable strategies for treating muscle insulin resistance in obesity and T2D as they can potentially restore whole body glucose disposal.
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Motshakeri M, Ebrahimi M, Goh YM, Matanjun P, Mohamed S. Sargassum polycystum reduces hyperglycaemia, dyslipidaemia and oxidative stress via increasing insulin sensitivity in a rat model of type 2 diabetes. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2013; 93:1772-8. [PMID: 23208488 DOI: 10.1002/jsfa.5971] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 09/23/2012] [Accepted: 10/26/2012] [Indexed: 01/10/2024]
Abstract
BACKGROUND Sargassum polycystum, a brown seaweed, contains various nutrients and bioactive compounds that have antioxidant and healing properties. The research hypothesises that antioxidants and pigments in dietary S. polycystum extracts can improve insulin sensitivity, blood sugar levels and blood lipid levels in a rat model of type 2 diabetes. The diabetes was induced by a high-sugar, high-fat diet for 16 weeks to enhance insulin resistance, followed by a low-dose intraperitoneal injection of streptozotocin (35 mg kg(-1) body weight). The doses of S. polycystum tested on diabetic rats were 150 and 300 mg kg(-1) body weight for the ethanolic extract or 150 and 300 mg kg(-1) for the water extract. Normal rats, untreated diabetic and metformin-treated diabetic rats (n = 6) were used as control. RESULTS Both doses of the alcohol extract of S. polycystum and the 300 mg kg(-1) water extract, significantly reduced blood glucose and glycosylated haemoglobin (HbA1C ) levels. Serum total cholesterol, triglyceride levels and plasma atherogenic index were significantly decreased after 22 days treatment in all seaweed groups. Unlike metformin, S. polycystum did not significantly change plasma insulin in the rats, but increased the response to insulin. CONCLUSION The consumption of either ethanolic or water extracts of S. polycystum dose dependently reduced dyslipidaemia in type 2 diabetic rats. S. polycystum is a potential insulin sensitiser, for a comestible complementary therapy in the management of type 2 diabetes which can help reduce atherogenic risk.
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Affiliation(s)
- Mahsa Motshakeri
- Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
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18
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Rinnankoski-Tuikka R, Silvennoinen M, Torvinen S, Hulmi JJ, Lehti M, Kivelä R, Reunanen H, Kainulainen H. Effects of high-fat diet and physical activity on pyruvate dehydrogenase kinase-4 in mouse skeletal muscle. Nutr Metab (Lond) 2012; 9:53. [PMID: 22682013 PMCID: PMC3407034 DOI: 10.1186/1743-7075-9-53] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 06/09/2012] [Indexed: 01/19/2023] Open
Abstract
Background The expression of PDK4 is elevated by diabetes, fasting and other conditions associated with the switch from the utilization of glucose to fatty acids as an energy source. It is previously shown that peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a master regulator of energy metabolism, coactivates in cell lines pyruvate dehydrogenase kinase-4 (PDK4) gene expression via the estrogen-related receptor α (ERRα). We investigated the effects of long-term high-fat diet and physical activity on the expression of PDK4, PGC-1α and ERRα and the amount and function of mitochondria in skeletal muscle. Methods Insulin resistance was induced by a high-fat (HF) diet for 19 weeks in C57BL/6 J mice, which were either sedentary or with access to running wheels. The skeletal muscle expression levels of PDK4, PGC-1α and ERRα were measured and the quality and quantity of mitochondrial function was assessed. Results The HF mice were more insulin-resistant than the low-fat (LF) -fed mice. Upregulation of PDK4 and ERRα mRNA and protein levels were seen after the HF diet, and when combined with running even more profound effects on the mRNA expression levels were observed. Chronic HF feeding and voluntary running did not have significant effects on PGC-1α mRNA or protein levels. No remarkable difference was found in the amount or function of mitochondria. Conclusions Our results support the view that insulin resistance is not mediated by the decreased qualitative or quantitative properties of mitochondria. Instead, the role of PDK4 should be contemplated as a possible contributor to high-fat diet-induced insulin resistance.
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Affiliation(s)
- Rita Rinnankoski-Tuikka
- Neuromuscular Research Center, Department of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland.
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Xu J, Zhou H, Yan X, Zhou C, Zhu P, Ma B. Effect of unialgal diets on the composition of fatty acids and sterols in juvenile ark shell Tegillarca granosa Linnaeus. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:3973-3980. [PMID: 22443233 DOI: 10.1021/jf300620e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This study has investigated the effects of six different unialgal diets ( Chaetoceros calcitrans , Platymonas helgolandica , Chlorella sp., Isochrysis galbana , Nannochloropsis oculata , and Pavlova viridis ) on the composition of fatty acids and sterols in juvenile ark shell Tegillarca granosa Linnaeus. The best feeding effects on the growth of shellfish were found in C. calcitrans, followed by I. galbana and P. viridis, whereas Chlorella sp. and N. oculata exhibited relatively poor effects. The fatty acid and sterol compositions in the six microalgae and the juvenile ark shell after feeding were analyzed, and 39 fatty acids and 18 sterols were identified. Although the results demonstrate a close correlation between the sterol compositions in algal species and juvenile ark shell, a similar correlation was not observed between fatty acids. In the juvenile ark shell fed microalgae, the ratio of total saturated fatty acids (SFA) rapidly decreases, whereas the proportion of total polyunsaturated fatty acids (PUFAs) increases considerably. The abundances of AA, EPA, and DHA increase most significantly in shellfish with better growth (fed C. calcitrans, I. galbana, and P. viridis). The number of sterol species is reduced, but the total sterol content in groups fed corresponding microalgae increases, and abundant plant sterols, instead of cholesterol, are accumulated in juvenile ark shell fed appropriate microalgae I. galbana and P. viridis. Therefore, to be more conducive to human health, I. galbana and P. viridis, of the six experimental microalgae, are recommended for artificial ark shell culture.
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Affiliation(s)
- Jilin Xu
- Key Laboratory of Applied Marine Biotechnology, Ningbo University , Chinese Ministry of Education, Ningbo, China
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20
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Kulkarni SS, Salehzadeh F, Fritz T, Zierath JR, Krook A, Osler ME. Mitochondrial regulators of fatty acid metabolism reflect metabolic dysfunction in type 2 diabetes mellitus. Metabolism 2012; 61:175-85. [PMID: 21816445 DOI: 10.1016/j.metabol.2011.06.014] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 06/17/2011] [Accepted: 06/20/2011] [Indexed: 10/25/2022]
Abstract
The delicate homeostatic balance between glucose and fatty acid metabolism in relation to whole-body energy regulation is influenced by mitochondrial function. We determined expression and regulation of mitochondrial enzymes including pyruvate dehydrogenase kinase (PDK) 4, PDK2, carnitine palmitoyltransferase 1b, and malonyl-coenzyme A decarboxylase in skeletal muscle from people with normal glucose tolerance (NGT) or type 2 diabetes mellitus (T2DM). Vastus lateralis biopsies were obtained from NGT (n = 79) or T2DM (n = 33) men and women matched for age and body mass index. A subset of participants participated in a 4-month lifestyle intervention program consisting of an unsupervised walking exercise. Muscle biopsies were analyzed for expression and DNA methylation status. Primary myotubes were derived from biopsies obtained from NGT individuals for metabolic studies. Cultured skeletal muscle was exposed to agents mimicking exercise activation for messenger RNA (mRNA) expression analysis. The mRNA expression of PDK4, PDK2, and malonyl-coenzyme A decarboxylase was increased in skeletal muscle from T2DM patients. Methylation of the PDK4 promoter was reduced in T2DM and inversely correlated with PDK4 expression. Moreover, PDK4 expression was positively correlated with body mass index, blood glucose, insulin, C peptide, and hemoglobin A(1c). A lifestyle intervention program resulted in increased PDK4 mRNA expression in NGT individuals, but not in those with T2DM. Exposure to caffeine or palmitate increased PDK4 mRNA in a cultured skeletal muscle system. Our findings reveal that skeletal muscle expression of PDK4 and related genes regulating mitochondrial function reflects alterations in substrate utilization and clinical features associated with T2DM. Furthermore, hypomethylation of the PDK4 promoter in T2DM coincided with an impaired response of PDK4 mRNA after exercise.
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MESH Headings
- Aged
- Biopsy
- Case-Control Studies
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/therapy
- Exercise Therapy
- Fatty Acids/metabolism
- Female
- Gene Expression Regulation, Enzymologic/physiology
- Humans
- Male
- Metabolic Diseases/etiology
- Metabolic Diseases/genetics
- Metabolic Diseases/metabolism
- Metabolic Diseases/therapy
- Middle Aged
- Mitochondria, Muscle/enzymology
- Mitochondria, Muscle/pathology
- Mitochondrial Proteins/genetics
- Mitochondrial Proteins/metabolism
- Mitochondrial Proteins/physiology
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Risk Reduction Behavior
- Walking/physiology
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Affiliation(s)
- Sameer S Kulkarni
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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21
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Shiose K, Tobina T, Higaki Y, Kiyonaga A, Tanaka H. Effectiveness of sub-maximal intermittent exercise on muscle glycogen depletion, PGC-1<i>α</i> and PDK-4 gene expression. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/ojmip.2012.24017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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22
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Herbst EAF, Dunford ECE, Harris RA, Vandenboom R, Leblanc PJ, Roy BD, Jeoung NH, Peters SJ. Role of pyruvate dehydrogenase kinase 4 in regulating PDH activation during acute muscle contraction. Appl Physiol Nutr Metab 2011; 37:48-52. [PMID: 22196220 DOI: 10.1139/h11-136] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The oxidation of carbohydrates in mammals is regulated by the pyruvate dehydrogenase (PDH) complex, which is covalently regulated by four PDH kinases (PDK1-4) and two PDH phosphatases (PDP1-2) unique to the PDH complex. To investigate the role that PDK4 plays in regulating PDH activation (PDHa) during muscle contraction, mouse extensor digitorum muscle was removed from wild type (WT) and PDK4-knockout (PDK4-KO) mice after a 24 h fast and stimulated for 3 min either at 10 Hz (low-intensity contraction), 40 Hz (moderate-intensity contraction), or allowed to rest. Force was recorded and muscle PDHa activity and metabolite concentrations were measured. PDHa activity was ∼2.5-fold higher at rest in PDK4-KO mice than WT mice (P = 0.009) and ∼2-fold higher in PDK4-KO mice at both 10 Hz (P < 0.001) and 40 Hz (P < 0.001). Force relative to muscle weight was similar at 10 Hz, but was 5.8 ± 0.7 mN·g(-1) in PDK4-KO mice and 3.5 ± 0.7 mN·g(-1) in WT mice at 40 Hz (P < 0.001), with a similar rate of fatigue in both genotypes. From these results it was concluded that PDK4 plays a role in reducing PDHa activity during low to moderate-intensity muscle stimulation, and that absence of PDK4 and the subsequent changes in carbohydrate utilization may alter force production.
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Affiliation(s)
- Eric A F Herbst
- Department of Kinesiology, Brock University, ON N1G 2W1, Canada
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23
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Kiilerich K, Ringholm S, Biensø RS, Fisher JP, Iversen N, van Hall G, Wojtaszewski JFP, Saltin B, Lundby C, Calbet JAL, Pilegaard H. Exercise-induced pyruvate dehydrogenase activation is not affected by 7 days of bed rest. J Appl Physiol (1985) 2011; 111:751-7. [DOI: 10.1152/japplphysiol.00063.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To test the hypothesis that physical inactivity impairs the exercise-induced modulation of pyruvate dehydrogenase (PDH), six healthy normally physically active male subjects completed 7 days of bed rest. Before and immediately after the bed rest, the subjects completed an oral glucose tolerance test (OGTT) and a one-legged knee extensor exercise bout [45 min at 60% maximal load (Wmax)] with muscle biopsies obtained from vastus lateralis before, immediately after exercise, and at 3 h of recovery. Blood samples were taken from the femoral vein and artery before and after 40 min of exercise. Glucose intake elicited a larger ( P ≤ 0.05) insulin response after bed rest than before, indicating glucose intolerance. There were no differences in lactate release/uptake across the exercising muscle before and after bed rest, but glucose uptake after 40 min of exercise was larger ( P ≤ 0.05) before bed rest than after. Muscle glycogen content tended to be higher (0.05< P ≤ 0.10) after bed rest than before, but muscle glycogen breakdown in response to exercise was similar before and after bed rest. PDH-E1α protein content did not change in response to bed rest or in response to the exercise intervention. Exercise increased ( P ≤ 0.05) the activity of PDH in the active form (PDHa) and induced ( P ≤ 0.05) dephosphorylation of PDH-E1α on Ser293, Ser295 and Ser300, with no difference before and after bed rest. In conclusion, although 7 days of bed rest induced whole body glucose intolerance, exercise-induced PDH regulation in skeletal muscle was not changed. This suggests that exercise-induced PDH regulation in skeletal muscle is maintained in glucose-intolerant (e.g., insulin resistant) individuals.
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Affiliation(s)
- Kristian Kiilerich
- Centre of Inflammation and Metabolism,
- Copenhagen Muscle Research Centre, and
- Department of Biology, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Stine Ringholm
- Centre of Inflammation and Metabolism,
- Copenhagen Muscle Research Centre, and
- Department of Biology, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus S. Biensø
- Centre of Inflammation and Metabolism,
- Copenhagen Muscle Research Centre, and
- Department of Biology, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - James P. Fisher
- School of Sport and Exercise Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Ninna Iversen
- Centre of Inflammation and Metabolism,
- Copenhagen Muscle Research Centre, and
- Department of Biology, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Gerrit van Hall
- Metabolic Mass-Spectrometry Facility, Rigshospitalet and Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen
| | - Jørgen F. P. Wojtaszewski
- Copenhagen Muscle Research Centre, and
- Section of Human Physiology, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen
| | - Bengt Saltin
- Copenhagen Muscle Research Centre, and
- Rigshospitalet, Section 7652, Copenhagen, Denmark; and
| | - Carsten Lundby
- Copenhagen Muscle Research Centre, and
- Rigshospitalet, Section 7652, Copenhagen, Denmark; and
| | - Jose A. L. Calbet
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands
| | - Henriette Pilegaard
- Centre of Inflammation and Metabolism,
- Copenhagen Muscle Research Centre, and
- Department of Biology, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
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Van Proeyen K, Szlufcik K, Nielens H, Deldicque L, Van Dyck R, Ramaekers M, Hespel P. High-fat diet overrules the effects of training on fiber-specific intramyocellular lipid utilization during exercise. J Appl Physiol (1985) 2011; 111:108-16. [PMID: 21551007 DOI: 10.1152/japplphysiol.01459.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In this study, we compared the effects of endurance training in the fasted state (F) vs. the fed state [ample carbohydrate intake (CHO)] on exercise-induced intramyocellular lipid (IMCL) and glycogen utilization during a 6-wk period of a hypercaloric (∼+30% kcal/day) fat-rich diet (HFD; 50% of kcal). Healthy male volunteers (18-25 yrs) received a HFD in conjunction with endurance training (four times, 60-90 min/wk) either in F (n = 10) or with CHO before and during exercise sessions (n = 10). The control group (n = 7) received a HFD without training and increased body weight by ∼3 kg (P < 0.001). Before and after a HFD, the subjects performed a 2-h constant-load bicycle exercise test in F at ∼70% maximal oxygen uptake rate. A HFD, both in the absence (F) or presence (CHO) of training, elevated basal IMCL content by ∼50% in type I and by ∼75% in type IIa fibers (P < 0.05). Independent of training in F or CHO, a HFD, as such, stimulated exercise-induced net IMCL breakdown by approximately twofold in type I and by approximately fourfold in type IIa fibers. Furthermore, exercise-induced net muscle glycogen breakdown was not significantly affected by a HFD. It is concluded that a HFD stimulates net IMCL degradation by increasing basal IMCL content during exercise in type I and especially IIa fibers. Furthermore, a hypercaloric HFD provides adequate amounts of carbohydrates to maintain high muscle glycogen content during training and does not impair exercise-induced muscle glycogen breakdown.
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Affiliation(s)
- Karen Van Proeyen
- Research Centre for Exercise and Health, Department of Biomedical Kinesiology, Katholieke Universiteit Leuven, Leuven, Belgium
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25
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Bibliography. Current world literature. Adrenal cortex. Curr Opin Endocrinol Diabetes Obes 2011; 18:231-3. [PMID: 21522003 DOI: 10.1097/med.0b013e3283457c7d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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26
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Dunford EC, Herbst EA, Jeoung NH, Gittings W, Inglis JG, Vandenboom R, LeBlanc PJ, Harris RA, Peters SJ. PDH activation during in vitro muscle contractions in PDH kinase 2 knockout mice: effect of PDH kinase 1 compensation. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1487-93. [PMID: 21411764 DOI: 10.1152/ajpregu.00498.2010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Pyruvate dehydrogenase (PDH) plays an important role in regulating carbohydrate oxidation in skeletal muscle. PDH is deactivated by a set of PDH kinases (PDK1, PDK2, PDK3, PDK4), with PDK2 and PDK4 being the most predominant isoforms in skeletal muscle. Although PDK2 is the most abundant isoform, few studies have examined its physiological role. The role of PDK2 on PDH activation (PDHa) at rest and during muscle stimulation at 10 and 40 Hz (eliciting low- and moderate-intensity muscle contractions, respectively) in isolated extensor digitorum longus muscles was studied in PDK2 knockout (PDK2KO) and wild-type (WT) mice (n = 5 per group). PDHa activity was unexpectedly 35 and 77% lower in PDK2KO than WT muscle (P = 0.043), while total PDK activity was nearly fourfold lower in PDK2KO muscle (P = 0.006). During 40-Hz contractions, initial force was lower in PDK2KO than WT muscle (P < 0.001) but fatigued similarly to ∼75% of initial force by 3 min. There were no differences in initial force or rate of fatigue during 10-Hz contractions. PDK1 compensated for the lack of PDK2 and was 1.8-fold higher in PDK2KO than WT muscle (P = 0.019). This likely contributed to ensuring that resting PDHa activity was similar between the groups and accounts for the lower PDH activation during muscle contraction, as PDK1 is a very potent inhibitor of the PDH complex. Increased PDK1 expression appears to be regulated by hypoxia inducible factor-1α, which was 3.5-fold higher in PDK2KO muscle. It is clear that PDK2 activity is essential, even at rest, in regulation of carbohydrate oxidation and production of reducing equivalents for the electron transport chain. In addition, these results underscore the importance of the overall kinetics of the PDK isoform population, rather than total PDK activity, in determining transformation of the PDH complex and PDHa activity during muscle contraction.
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Affiliation(s)
- Emily C Dunford
- Centre for Muscle Metabolism and Biophysics, Brock University, St. Catharines, Ontario, Canada
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27
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Hulston CJ, Venables MC, Mann CH, Martin C, Philp A, Baar K, Jeukendrup AE. Training with low muscle glycogen enhances fat metabolism in well-trained cyclists. Med Sci Sports Exerc 2011; 42:2046-55. [PMID: 20351596 DOI: 10.1249/mss.0b013e3181dd5070] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE To determine the effects of training with low muscle glycogen on exercise performance, substrate metabolism, and skeletal muscle adaptation. METHODS Fourteen well-trained cyclists were pair-matched and randomly assigned to HIGH- or LOW-glycogen training groups. Subjects performed nine aerobic training (AT; 90 min at 70% VO2max) and nine high-intensity interval training sessions (HIT; 8 × 5-min efforts, 1-min recovery) during a 3-wk period. HIGH trained once daily, alternating between AT on day 1 and HIT the following day, whereas LOW trained twice every second day, first performing AT and then, 1 h later, performing HIT. Pretraining and posttraining measures were a resting muscle biopsy, metabolic measures during steady-state cycling, and a time trial. RESULTS Power output during HIT was 297 ± 8 W in LOW compared with 323 ± 9 W in HIGH (P < 0.05); however, time trial performance improved by ∼10% in both groups (P < 0.05). Fat oxidation during steady-state cycling increased after training in LOW (from 26 ± 2 to 34 ± 2 μmol·kg−¹·min−¹, P < 0.01). Plasma free fatty acid oxidation was similar before and after training in both groups, but muscle-derived triacylglycerol oxidation increased after training in LOW (from 16 ± 1 to 23 ± 1 μmol·kg−¹·min−¹, P < 0.05). Training with low muscle glycogen also increased β-hydroxyacyl-CoA-dehydrogenase protein content (P < 0.01). CONCLUSIONS Training with low muscle glycogen reduced training intensity and, in performance, was no more effective than training with high muscle glycogen. However, fat oxidation was increased after training with low muscle glycogen, which may have been due to the enhanced metabolic adaptations in skeletal muscle.
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Affiliation(s)
- Carl J Hulston
- School of Sport and Exercise Sciences, University of Birmingham, Birmingham, United Kingdom
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Kiilerich K, Adser H, Jakobsen AH, Pedersen PA, Hardie DG, Wojtaszewski JFP, Pilegaard H. PGC-1alpha increases PDH content but does not change acute PDH regulation in mouse skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2010; 299:R1350-9. [PMID: 20720174 DOI: 10.1152/ajpregu.00400.2010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this study was to test whether the transcriptional coactivator peroxisome proliferator-activated receptor (PPAR)-γ coactivator (PGC)1α regulates the content of pyruvate dehydrogenase (PDH)-E1α and influences PDH activity through regulation of pyruvate dehydrogenase kinase-4 (PDK4) expression and subsequently PDH phosphorylation. PGC-1α whole body knockout (KO), muscle-specific PGC-1α overexpressing mice (MCK PGC-1α), and littermate wild-type (WT) mice underwent two interventions known to affect PDH. Quadriceps muscles were removed from fed and 24-h fasted mice as well as at 6 h of recovery after 1-h running and from mice that did not run acutely. PDH-E1α protein content and PDH-E1α phosphorylation were lower in PGC-1α KO and higher in MCK PGC-1α mice at rest, but, while MCK PGC-1α had higher PDK4 protein content, KO of PGC-1α had no effect on PDK4 protein content. The differences in phosphorylation partly vanished when expressing phosphorylation relative to the PDH-E1α content with only a maintained elevated phosphorylation in MCK PGC-1α mice. Fasting upregulated PDK4 protein in PGC-1α KO, MCK PGC-1α and WT mice, but this was not consistently associated with increased PDH-E1α phosphorylation. Downregulation of the activity of PDH in the active form (PDHa) at 6-h recovery from exercise in both the PGC-1α KO and MCK PGC-1α mice and the association between PDH-E1α phosphorylation and PDHa activity in PGC-1α KO mice indicate that PGC-1α is not required for these responses. In conclusion, PGC-1α regulates PDH-E1α protein content in parallel with mitochondrial oxidative proteins, but does not seem to influence PDH regulation in mouse skeletal muscle in response to fasting and in recovery from exercise.
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Affiliation(s)
- Kristian Kiilerich
- Centre of Inflammation and Metabolism, August Krogh Bldg., Dept. of Biology, Universitetsparken 13, 2100 Copenhagen, Denmark.
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